Safety FAQ

About This Page

This Safety FAQ is the Level 3 educational reference for the HL Supps catalogue. It exists because every advanced supplement in our arsenal — DMHA pre-workouts, prohormones, SARMs, research peptides, ECA fat burners — comes with regulatory complexity, drug-interaction profiles, and bloodwork considerations that don't fit on a product label.

The information here is educational, not prescriptive. It does not replace consultation with a physician, licensed pharmacist, or sports endocrinologist. If you're stacking compounds, running a cycle, or sourcing internationally — read the relevant section below, then talk to a qualified clinician before you act.

Updated quarterly. Regulatory status of compounds (DMAA, DMHA, peptides, SARMs) shifts as national authorities issue new guidance. The dates in each answer indicate when the regulatory information was last verified.

If your question isn't covered here, contact us at info@hlsupps.com — we add new questions to this page each quarter based on what comes through support.

Table of Contents

A. Compound Legality & EU Regulation

1. Is DMAA legal in the UK, Germany, and France in 2026?
2. Are peptides legal in the EU?
3. Can I order BPC-157 to my country? What are the customs risks?
4. Do I need a prescription for enclomiphene in the EU?

B. Drug Interactions & Stacking Safety
5. Can I take yohimbine with coffee?
6. Can I stack DMHA with yohimbine?
7. Can I take a pre-workout while on SSRIs or MAOIs?

C. Cycle Support, PCT & Bloodwork
8. What blood markers should I track on a prohormone cycle?
9. Do I need cycle support on a SARM cycle?
10. Does a testosterone booster affect fertility?
11. How long should I stop pre-workout before bloodwork?

D. Substance-Specific Profiles
12. How long does DMHA stay in your system?
13. Is turkesterone safe long-term?
14. What's the difference between SARMs and prohormones?

E. Quality, Sourcing & Labeling
15. What's the difference between RUO and dietary supplement labeling?
16. How do I read a Certificate of Analysis (COA)?
17. Is DHEA legal in EU dietary supplements?
18. Why is berberine under EU review, and what does ANSES say?
19. Mucuna pruriens in a pre-workout — what does the L-DOPA content mean?
20. Akkermansia muciniphila and the word "probiotic" — what is the EU status?
21. Is a "caffeine-free" pre-workout with paraxanthine actually stim-free?
22. Piperine (BioPerine®) — why does 5–10 mg matter?

A. Compound Legality & EU Regulation

Q1. Is DMAA legal in the UK, Germany, and France in 2026?

The short answer: DMAA (1,3-dimethylamylamine) is not approved as a dietary supplement ingredient in the UK, Germany, France, or anywhere in the EU. Possession for personal use exists in a regulatory grey zone in most jurisdictions, but commercial sale labelled as a "food supplement" is banned.

The longer answer:

The FDA issued warning letters to DMAA-containing supplement manufacturers starting in 2012 and has classified DMAA as not a legitimate dietary ingredient¹. The European Food Safety Authority (EFSA) reached parallel conclusions in subsequent reviews. National-level enforcement varies:

• UK (FSA): DMAA is not authorised as a Novel Food. Selling DMAA-containing products as "food supplements" is illegal. Enforcement targets sellers, not buyers.
• Germany (BfArM): DMAA is classified as an unauthorised substance. Importation in commercial quantities is intercepted at customs.
• France (ANSES): DMAA banned from dietary supplements; products containing DMAA are removed from market on detection.
• Netherlands (NVWA): Similar framework — banned as supplement ingredient. This is why DMAA-containing products at HL Supps are categorised as advanced supplements for informed athletes 21+, not as dietary supplements.

Why this matters for the buyer: ordering DMAA across borders sometimes results in customs hold-ups. The legal exposure for personal-use possession is generally low across the EU, but commercial possession (multiple containers, evidence of intent to resell) escalates the risk profile significantly.

The HL Supps approach: we sell DMAA-containing formulas with clear labelling, country-specific shipping disclosures at checkout, and the convention "advanced supplement / compound for informed athletes 21+" rather than the misleading "dietary supplement" framing. Read the Advanced Pre-Workout Guide for the full pharmacology of DMAA and its alternatives (DMHA, geranium, Eria Jarensis).

Q2. Are peptides legal in the EU?

The short answer: Research peptides (BPC-157, TB-500, GHK-Cu, epithalon, ipamorelin) are not registered as medicinal products in the EU and not authorised as food supplements. They are sold as research chemicals (RUO — Research Use Only) under the legal framework for substances intended for laboratory work.

The longer answer:

The EMA (European Medicines Agency) has not approved any of the common research peptides for therapeutic use in humans. This means:

• BPC-157, TB-500, GHK-Cu (systemic), epithalon, MOTS-c, ipamorelin, CJC-1295, PT-141: all classified as research chemicals, no marketing authorisation
• Semaglutide / tirzepatide as RUO research compounds: distinct from the registered pharmaceutical forms (Ozempic®, Wegovy®, Mounjaro®, Zepbound®), which require a prescription and clinical supervision
• GHK-Cu in cosmetics: separately regulated under the Cosmetic Regulation (EC 1223/2009) — cosmetic claims permitted, medical claims prohibited

The EU-wide framework allows research chemicals to be sold for laboratory use. Member states have varying enforcement intensity:

• Netherlands: explicit research chemical category, low enforcement on personal possession
• UK (post-Brexit): MHRA monitors marketing claims, not personal possession of unscheduled compounds
• Germany: Arzneimittelgesetz (drug law) framework — peptides without medical authorisation cannot be marketed for human use
• France, Italy, Spain: similar framework, occasional enforcement against retailers with explicit therapeutic marketing

The buyer's reality: ordering RUO peptides for personal use exists in a regulatory grey zone across most of the EU. Customs interception is possible but uncommon for single-vial orders. Bulk orders, repeated shipments, or any communication framing the order as medicinal use raises the regulatory exposure considerably.

Critical caveat: "RUO peptide" labelling does not equal "safe for human use." It means the substance hasn't been through the clinical trial process required for pharmaceutical authorisation. Side-effect profiles, drug interactions, and long-term safety data are largely unestablished for most research peptides².

Read the Pillar V: Recovery & Athlete Longevity for more on peptide pharmacology.

Q3. Can I order BPC-157 to my country? What are the customs risks?

The short answer: Customs risk varies dramatically by destination country. Within the EU single market, a single vial sent from the Netherlands to most member states clears without incident in the vast majority of cases. Outside the EU (UK post-Brexit, US, AU, CA), customs interception is more common — and the risk profile depends on local pharmaceutical law.

Country-by-country assessment (verified 2026-Q3, subject to change):

What customs interception typically means:

• Shipment held, opened, contents reviewed
• "Notification of seizure" letter to the recipient
• In most personal-use cases: no further legal action; the substance is destroyed
• In commercial-quantity cases: investigation, possible prosecution under controlled substances or pharmaceutical law

The HL Supps shipping policy:

• We ship from the Netherlands hub for fastest EU clearance
• We comply with country-specific export restrictions (some peptides not shipped to certain destinations on principle)
• We provide tracking but no warranty against customs interception
• Re-shipment of seized orders is not included in our policy — customs risk transfers to the buyer at checkout

If the destination country in your case isn't listed above, contact us at info@hlsupps.com before ordering and we'll provide the most current shipping guidance.

Q4. Do I need a prescription for enclomiphene in the EU?

The short answer: Yes — enclomiphene citrate is a prescription medication across the EU. The same applies to its parent compound, clomiphene (Clomid®), and to other SERMs (selective estrogen receptor modulators) such as tamoxifen (Nolvadex®) and raloxifene (Evista®).

The longer answer:

Enclomiphene citrate is the trans-isomer of clomiphene, a SERM with antagonist activity at hypothalamic estrogen receptors. It blocks estrogen-mediated negative feedback on the HPG (hypothalamic-pituitary-gonadal) axis, increasing GnRH release, which drives LH and FSH secretion, which stimulates endogenous testosterone production³. This mechanism makes enclomiphene one of the most-studied compounds for post-cycle therapy (PCT) after suppressive cycles (anabolic steroid cycles, high-dose prohormone cycles, certain SARM cycles).

Regulatory status across EU:

• All EU member states: prescription-only medication when sold for human use under therapeutic claims
• Sale as "research chemical / RUO": falls under the same grey zone as research peptides (Q2 above). Enclomiphene labelled RUO can be sourced legally in the Netherlands and several other member states, but the framing matters
• Marketing as "PCT supplement": a regulatory red flag that triggers enforcement against the seller

The PCT reality for the informed athlete:

If you're running a suppressive cycle (prohormone, SARM with HPG suppression risk, anabolic), the standard PCT framework typically includes enclomiphene at 12.5–25 mg daily for 4–6 weeks, sometimes stacked with HCG or aromatase inhibitors depending on the specific cycle⁴. This protocol exists in clinical literature, but executing it without medical supervision means:

• No baseline bloodwork to identify pre-existing endocrine issues
• No mid-cycle monitoring of LH, FSH, total/free testosterone, estradiol
• No oversight of contraindications (history of liver disease, certain cancers, thrombotic risk)
• No prescription channel for enclomiphene if you take the recommended path

The HL Supps position: we treat PCT as a medical protocol that requires clinical supervision — not a supplementation regimen. We provide educational content on PCT mechanics (Pillar II: Testosterone, PCT & Cycle Support) but we do not offer prescription SERMs in our catalogue. For lifters serious about cycle work, the right move is finding a TRT/men's-health clinic that performs cycle bloodwork and prescribes the SERM legally.

Pharmacological Perspective — Dr. [PharmD]

"Enclomiphene is a clean SERM with a relatively narrow side-effect profile in healthy adults at standard PCT doses. The clinical issue isn't typically the compound — it's the absence of bloodwork to confirm whether PCT is actually needed and whether it's working. Hot tip: not every cycle requires SERM-based PCT, and some athletes recover on their own with time. Bloodwork tells you which scenario you're in. The right clinician interprets that. Don't guess on this stuff — measure it."

B. Drug Interactions & Stacking Safety

Q5. Can I take yohimbine with coffee?

The short answer: Yes, but with deliberate dosing. The combination is a potentiated noradrenergic stimulus — yohimbine antagonises pre-synaptic α2-adrenergic auto-receptors (increasing noradrenaline release) while caffeine antagonises adenosine receptors (also disinhibiting catecholamine release). Stacking them isn't pharmacologically dangerous in healthy adults at moderate doses, but the combined cardiovascular load is non-trivial⁵.

Practical guidance:

• First-time users: never stack yohimbine and a high-dose pre-workout simultaneously. Start with one variable at a time
• Yohimbine dose: the ergogenic / fat-loss range in the literature is 0.2 mg/kg body weight. For an 80 kg lifter that's ~16 mg. Most products dose 5–10 mg per serving — start with one serving with morning coffee on an empty stomach
• Caffeine dose: if combining with yohimbine, keep total caffeine below 200 mg until you've assessed cardiovascular response
• Timing: yohimbine has a relatively short half-life (~36 min in the active form, with longer-acting metabolites). Coffee shortly before yohimbine compounds the peak rather than spreading it
• Don't combine on training days where you also use a Tier-3 stimulant pre-workout — that's three layers of catecholamine drive on one nervous system

Contraindications (do not combine):

• Diagnosed hypertension or arrhythmia
• Concurrent SSRI, SNRI, or MAOI use (serotonin syndrome risk, hypertensive crisis risk)
• Anxiety disorders, panic disorder
• Pregnancy
• Liver or kidney impairment
• Within 8 hours of bedtime

Signs you went too far: racing heart at rest, anxiety that doesn't subside, hand tremor, hypertensive symptoms (headache, visual disturbance). If any appear — discontinue, hydrate, and reassess dosing for next time. If symptoms persist, seek medical evaluation.

Browse the Fat Burners selection → for our yohimbine and α-yohimbine product range, and read Pillar IV: Fat Loss & Thermogenic Stacking for the broader stacking framework.

Q6. Can I stack DMHA with yohimbine?

The short answer: This stack is for advanced users only and should not be a daily protocol. The combination produces an aggressive noradrenergic profile — potent ergogenic effect, high cardiovascular load, fast tolerance buildup, hard crash. If you're not already comfortable with each compound separately, don't stack them.

Pharmacology of the combination:

DMHA (2-aminoisoheptane) is a catecholamine releaser with sympathomimetic activity — pushes noradrenaline and dopamine into the synapse from pre-synaptic vesicles. Yohimbine antagonises α2-adrenergic auto-receptors, which removes the brake on noradrenaline release. Stack them and you have one compound pushing the accelerator while the other disables the cruise control on noradrenaline output.

The result for performance: aggressive focus, vasoconstriction-then-dilation pattern, elevated heart rate, sustained "tunnel vision" focus on the lift.

The result for the system: HPA-axis activation, catecholamine pool depletion accelerated (see Pre-Workout Tolerance Explained), cardiovascular load that doesn't reset for hours after training.

If you do this stack, do it deliberately:

• Frequency: maximum 1–2 sessions per week. Not the daily driver
• Dose: start low. DMHA 75–125 mg, yohimbine 5 mg. Build only after multiple sessions confirm tolerance
• Cycle: 4–6 weeks maximum, then a complete stim washout (minimum 10–14 days)
• Bloodwork: baseline blood pressure, resting heart rate, lipid panel before starting; reassess at week 4
• No additional caffeine above 200 mg during the stack window — the noradrenergic load is already maximal
• No SSRIs, MAOIs, ADHD medications, or other CNS-active prescriptions concurrently
• Stop immediately if persistent hypertension, chest pain, arrhythmia, severe anxiety, or sleep collapse develops

Pharmacological Perspective — Dr. [PharmD]

"From a cardiovascular standpoint, this stack puts more noradrenergic load on the heart than most prescription stimulants used in adult ADHD. The acute risk in a healthy adult at conservative doses is low — but it's not zero. The chronic risk profile (resting blood pressure, ventricular remodelling with prolonged use) is largely uncharacterised in the recreational-use population because the studies haven't been done. Translation: we don't fully know what daily DMHA + yohimbine over 12 months does to a 35-year-old's heart. The conservative move is to treat this stack as an occasional protocol, not a default."

Q7. Can I take a pre-workout while on SSRIs or MAOIs?

The short answer: This is a medical question, not a supplementation question. The combination of advanced pre-workout stimulants (DMHA, geranium, Eria Jarensis, yohimbine, high-dose synephrine) with serotonergic or monoamine-oxidase-inhibiting medications carries genuine risk — including serotonin syndrome and hypertensive crisis. Discuss with your prescribing physician before any decision.

The pharmacology — why this matters:

SSRIs (sertraline, escitalopram, fluoxetine, paroxetine): block serotonin reuptake, raising synaptic serotonin. Stacking with sympathomimetic compounds that also affect serotonin (some pre-workout stimulants, MDMA-class research chemicals, high-dose St. John's Wort) can precipitate serotonin syndrome — a medical emergency characterised by hyperthermia, agitation, neuromuscular abnormalities, and autonomic instability⁶.

MAOIs (phenelzine, tranylcypromine, selegiline): block monoamine oxidase, dramatically reducing breakdown of catecholamines and tyramine. Stacking with any sympathomimetic compound — DMAA, DMHA, ephedrine, high-dose synephrine, even some over-the-counter cold medicines — risks hypertensive crisis with potential cardiovascular catastrophe⁷.

SNRIs (venlafaxine, duloxetine): combined SERT + NET inhibition. Risk profile similar to SSRIs plus additional noradrenergic load.

Practical guidance for the lifter on prescribed psychiatric medication:

• Mainstream pre-workouts (caffeine 200 mg + citrulline + beta-alanine, no DMHA / yohimbine / advanced stims): generally lower risk, but still discuss with your prescriber
• Advanced pre-workouts (Tier 2 and Tier 3 in the framework): do not stack without explicit clinician sign-off
• Cycle washout windows: if your prescriber clears occasional use, run conservative timing — never close to dose, never on multiple consecutive days
• Fat burners with stimulants (ECA stacks, DMHA-based formulas, yohimbine-heavy products): treat with the same caution as advanced pre-workouts

The HL Supps position: we don't gatekeep purchases based on medical history (we have no way to verify), but we provide this educational content explicitly because the wrong stack on the wrong medication is a medical event, not a "tolerance issue." If you're on prescribed psychiatric medication, your supplement decisions need to involve the clinician who prescribed it.

Read Pillar I: Pre-Workout & CNS Pharmacology for the broader CNS pharmacology context.

C. Cycle Support, PCT & Bloodwork

Q8. What blood markers should I track on a prohormone cycle?

The short answer: At minimum — liver function panel, lipid panel, total and free testosterone, estradiol, LH, FSH, hematocrit, blood pressure. Baseline before cycle, mid-cycle (week 3–4), and 4 weeks after PCT completion. If you're not willing to do this — you're not ready to run the cycle.

The full bloodwork protocol:

Practical implementation:

• Use a TRT/men's-health clinic that runs comprehensive panels — the standard NHS / GP basic panel typically misses estradiol and free testosterone
• Bloodwork costs: budget €150–250 per panel in private EU clinics; €80–150 in some online lab services
• Schedule cycle around bloodwork dates, not the other way around
• If LFTs climb >2× upper limit of normal (ULN) at mid-cycle: stop the cycle, run liver-protective compounds (TUDCA, NAC, milk thistle), retest in 4 weeks
• If HDL drops below 25 mg/dL or hematocrit climbs above 54%: stop the cycle, address cardiovascular risk
• Post-PCT bloodwork at week 4 confirms whether HPTA recovered; if testosterone and LH are still suppressed, extend PCT or seek clinical follow-up

Why this is non-negotiable:

The data on long-term cardiovascular and hepatic outcomes from prohormone use is sparse but suggestive — case reports of cholestatic hepatitis, severe lipid derangement, and cardiomyopathy in chronic users are well-documented⁸. The single best risk-mitigation intervention available to the prohormone user is bloodwork. Marketing copy will not save your liver. Numbers on a panel will tell you whether to continue.

Pharmacological Perspective — Dr. [PharmD]

"The athletes who run prohormones safely over the long arc are not the ones with the best cycle support stack. They're the ones who book their bloodwork before they order the compound and stop the cycle when the numbers say so. Cycle support compounds (TUDCA, NAC, milk thistle, fish oil) reduce the hepatic and lipid burden — they don't eliminate it. Treat them as risk reduction, not insurance."

Browse Mass Up category → and Read Pillar II: Testosterone, PCT & Cycle Support for the full cycle architecture.

Q9. Do I need cycle support on a SARM cycle?

The short answer: Yes — though the support stack differs from prohormone cycle support. The primary risks on most SARM cycles are HPTA suppression (particularly with RAD-140, LGD-4033, S-23) and, for some compounds, lipid disturbance (particularly LGD-4033). Liver stress is generally lower than with methylated prohormones but not zero.

Compound-specific risk profile:

Standard SARM cycle support framework:

1. On-cycle:

   • Fish oil 2–4 g/day (lipid support)
   • High-quality multivitamin
   • Adequate protein intake (1.6–2.2 g/kg)
   • Optional: NAC 600–1200 mg/day if oxidative stress markers were borderline at baseline
   • Optional: milk thistle / silymarin if running multiple SARMs concurrently

2. PCT (for HPTA-suppressing SARMs — RAD-140, LGD-4033, S-23, YK-11):

   • Enclomiphene 12.5–25 mg daily for 4–6 weeks (prescription required — see Q4)
   • Or natural PCT framework (zinc, ashwagandha, tongkat ali, fadogia agrestis) for milder suppression cases — less effective but doesn't require a prescription
   • Bloodwork at week 4 post-PCT to confirm recovery

3. Bloodwork same as prohormone protocol (Q8 above), with emphasis on:

   • Total + free testosterone
   • LH + FSH
   • Estradiol
   • Lipid panel
   • LFTs (less critical than for methylated prohormones, but still indicated)

Critical reminder: SARMs are research chemicals (RUO) in the EU and US — not approved for human use. The clinical literature on long-term safety in healthy adults is sparse. Most evidence on dose-response, side-effect profiles, and recovery patterns comes from anecdotal community reporting, not RCTs. Treat the support and PCT framework as risk mitigation, not risk elimination.

Read Pillar II: Testosterone, PCT & Cycle Support for full cycle frameworks.

Q10. Does a testosterone booster affect fertility?

The short answer: Depends on what compound is in the "testosterone booster." Natural test boosters (fadogia agrestis, tongkat ali, ashwagandha, zinc, vitamin D) generally do not impair fertility and may modestly support it through different mechanisms. Prohormones, SARMs, and exogenous testosterone preparations can suppress endogenous LH and FSH, which directly impairs spermatogenesis — sometimes reversibly, sometimes not.

Compound class breakdown:

Natural boosters — fertility neutral or supportive:

• Tongkat ali (Eurycoma longifolia): RCT evidence suggests possible improvement in sperm parameters in subfertile men⁹
• Ashwagandha (Withania somnifera): RCT evidence suggests improvement in sperm count and motility in men with low sperm count
• Zinc: essential cofactor in spermatogenesis; deficiency impairs fertility
• Vitamin D: receptors present in testes; deficiency associated with lower sperm quality
• Fadogia agrestis: human data limited; mechanism (LH stimulation) is not directly suppressive of spermatogenesis

Prohormones, SARMs, exogenous testosterone — fertility-suppressing:

These compounds suppress the HPG axis through negative feedback. The cascade:

• Exogenous androgen / SARM → hypothalamus reduces GnRH → pituitary reduces LH and FSH → testes reduce intratesticular testosterone (ITT) and stop spermatogenesis
• ITT, not serum testosterone, is the driver of sperm production
• TRT-dose exogenous testosterone reduces ITT to near-zero within weeks
• Prohormone cycles suppress for the cycle duration plus recovery period
• Recovery time after a single 8–12 week cycle: typically 3–6 months in younger users, longer in older users or repeat cyclers

Practical guidance for men planning a family:

• Trying to conceive: avoid all suppressive compounds. Stick to natural boosters with documented sperm-supportive profiles
• Recently completed cycle, want to conceive in 6 months: sperm analysis at 3 months post-PCT to confirm recovery; clinical follow-up if counts remain depressed
• TRT users wanting to preserve fertility: discuss HCG / enclomiphene co-therapy with your prescribing clinician — these can preserve some intratesticular testosterone while on TRT
• Long-term recreational cycler: sperm analysis as part of routine bloodwork, particularly if planning a family in the next 1–2 years

Pharmacological Perspective — Dr. [PharmD]

"Most fertility recovery after a single suppressive cycle is good in healthy men under 35. The lifters who run into permanent issues typically share two patterns: long-duration cycles back-to-back with inadequate recovery between, or an underlying fertility issue that was unmasked by the cycle rather than caused by it. Sperm analysis is cheap and decisive. If fertility matters to you, measure it before assuming."

Browse Booster Testosterone category → for our natural test booster range.

Q11. How long should I stop pre-workout before bloodwork?

The short answer: Minimum 48–72 hours for a standard pre-workout to clear the acute effects on heart rate, blood pressure, lipid markers, and stress hormones. 7–10 days for a more accurate baseline if you're tracking cycle effects, HPA-axis recovery, or testosterone normalisation.

What pre-workout compounds confound on bloodwork:

Practical bloodwork prep protocol:

For a routine pre-cycle baseline (you want clean numbers to interpret later mid-cycle):

• 7-day washout: zero pre-workout, low caffeine (1 cup coffee morning maximum), no fat burners, no yohimbine
• Last training session 48 h before draw (light technical work or rest)
• Hydrate well 24 h before
• Fasting: 12 h overnight for lipid panel, glucose, HbA1c (unchanged); coffee black is fine for non-fasting markers
• Sleep: 8 h the night before

For a mid-cycle check while continuing the cycle:

• 48 h washout from pre-workout
• Continue the cycle compound (you want to see what the cycle is doing, not what the cycle does without stim load)
• Last training session 24 h before draw
• Standard fasting

For a post-cycle / post-PCT recovery confirmation:

• 10–14 day washout from all stimulants
• Last training session 72 h before draw
• This is when you want maximally clean numbers — rushed bloodwork at this point misses recovery patterns

Pharmacological Perspective — Dr. [PharmD]

"The most common mistake we see in lifter bloodwork: numbers drawn the morning after a heavy-stim training session, then panic when ALT is elevated and total testosterone is on the lower end. Both effects are acute — they don't reflect the chronic cycle state. The right move is the 7-day washout before the draw and the 48 h training-rest before the draw. Spending €200 on a panel that doesn't tell you anything reliable is wasted spend."

D. Substance-Specific Profiles

Q12. How long does DMHA stay in your system?

The short answer: DMHA (2-aminoisoheptane) has an estimated half-life of 8–12 hours in healthy adults. Active effects last 4–6 hours after dosing; full elimination from systemic circulation takes approximately 36–48 hours. Detection windows on standard drug tests are not a concern for most lifters (DMHA is not on the standard panel), but competitive athletes subject to WADA / sport-specific testing should treat DMHA as a flagged sympathomimetic with potential cross-reactivity on amphetamine immunoassays.

Pharmacokinetic profile (estimated from limited published data):

• Tmax (peak concentration): 1–2 hours post-oral-dose
• Half-life: estimated 8–12 hours in healthy adults
• Time to clinically negligible levels: 36–48 hours (5 half-lives)
• Detection window: urine immunoassay cross-reactivity possible up to 72 h depending on test sensitivity
• WADA status: structurally similar to DMAA, which is on the prohibited list. DMHA itself has been the subject of WADA monitoring; athletes subject to in-competition testing should not use DMHA without verifying current sport-specific rules

Practical implications:

• Daily dosing: strongly discouraged. With an 8–12 h half-life, daily dosing produces accumulating plasma levels for 3–4 days before reaching steady state — and steady-state concentration is what drives tolerance and HPA-axis dysregulation
• 2x/week dosing: the most common protocol among informed users — heavy stim sessions on Day 1 and Day 4, recovery on intervening days
• Pre-bedtime dose calculation: the "no caffeine after 2 PM" rule applies even more strictly to DMHA. A dose at 6 PM still has measurable levels at midnight, disrupting sleep architecture
• Drug test concern: for occupational testing (truck drivers, certain regulated professions), the cross-reactivity on amphetamine immunoassays has been reported — confirm the assay specifics with your testing programme before use
• Interaction window: DMHA effects on heart rate, blood pressure, and CNS load persist for the full 8–12 h half-life. Stacking with yohimbine, additional caffeine, fat burners, or any other sympathomimetic during this window compounds the cardiovascular load

Practical reality: the lifter who responds to fading DMHA effects by taking another scoop in the afternoon is creating a 16–18 h sympathomimetic window with cumulative half-lives. This is the textbook recipe for HPA-axis dysregulation and CNS burnout. Read Pre-Workout Tolerance Explained for the full recovery framework.

From the athlete's perspective — Coach Max

"DMHA is a tool, not a daily driver. The lifters I've coached who got sustained value from it ran it 1–2x per week for the heaviest sessions, kept it out of the 'maintenance' training days, and never stacked it with yohimbine on the same day. The ones who burnt out on it took it daily for three months and wondered why nothing felt right anymore. The half-life is the warning label. Read it."

Q13. Is turkesterone safe long-term?

The short answer: Probably yes, based on current evidence — but the honest qualifier is that long-term human safety data is sparse. Turkesterone (an ecdysteroid extracted primarily from Ajuga turkestanica) has been used in Soviet sports research since the 1980s with no widely-reported serious adverse events, but the bulk of mechanistic data comes from in vitro and rodent studies, not multi-year human trials¹⁰.

What we know:

• Turkesterone is an ecdysteroid — a class of compounds structurally distinct from anabolic-androgenic steroids. Mechanism appears to involve modulation of estrogen receptor beta (ERβ) and possibly mTOR signaling, not the androgen receptor
• No HPTA suppression in available human data (LH, FSH, testosterone unaffected at typical doses)
• No hepatic toxicity signals in rodent studies up to multi-month durations
• No cardiovascular impact at typical dosing
• No documented endocrine disruption in available human studies

What we don't know:

• Long-term (multi-year) human safety profile in healthy adults using daily dosing
• Effects on female reproductive endocrinology (limited human data in women)
• Interactions with prescribed medications (unstudied for most pharmaceutical classes)
• Whether reported ergogenic effects translate to RCT-level evidence (mixed and limited)

Practical guidance:

• Typical dose: 250–500 mg per serving, 1–3x daily
• Cycle approach: the conservative protocol is 8–12 weeks on, 4–6 weeks off — not because there's evidence of harm from continuous use, but because the long-term human data simply doesn't exist to justify indefinite use without breaks
• Bioavailability concern: turkesterone has historically poor oral bioavailability. Some products formulate with cyclodextrin complexes or other absorption enhancers; the practical ergogenic difference between formulations is debated
• Stacking: generally well-tolerated with other naturals (creatine, beta-alanine, citrulline). No documented interactions with mainstream training supplements
• Bloodwork: no specific markers required, but if running for >6 months, an annual standard panel (LFTs, lipids, CBC, total testosterone) provides baseline confirmation that nothing unexpected is happening

The honest framing:

Turkesterone is promising but evidence-incomplete. The mechanism profile is interesting and suggests a relatively benign safety footprint. The marketing claims (especially around mass gain comparable to anabolic compounds) significantly outrun the evidence base. The right framing for the informed athlete: turkesterone is a reasonable addition to a natural anabolic stack with a low risk profile and modest expected benefit, not a step-change compound¹¹.

Browse Mass Up category → and Read Pillar III: Mass & Natural Anabolics for the broader natural anabolics context.

Q14. What's the difference between SARMs and prohormones?

The short answer: Both increase anabolic signaling at the androgen receptor, but through different mechanisms with different side-effect profiles. Prohormones are precursor compounds metabolised to active androgens (similar to traditional anabolic steroids in effect). SARMs are non-steroidal compounds designed to selectively activate androgen receptors in muscle and bone tissue while sparing other tissues (prostate, sebaceous glands) — though selectivity in practice is imperfect.

Side-by-side comparison:

Practical decision framework — when each makes sense (acknowledging neither is "safe"):

Lifter considering prohormone:

• Has 5+ years of training experience and consistent natural progression
• Has comprehensive bloodwork access and a clinician who'll review it
• Has a complete cycle support stack ready (TUDCA, NAC, milk thistle, fish oil, multi)
• Has a complete PCT framework (SERM access, bloodwork at week 4 post-PCT)
• Understands that methylated compounds carry meaningful hepatic risk even with support

Lifter considering SARM:

• Same prerequisites as above
• Selecting compound based on goal: Ostarine for recomp / mild bulk, LGD-4033 for size, RAD-140 for strength + recomp, MK-677 for sleep + recovery (not anabolic per se), Cardarine for endurance (PPARδ, not androgen)
• Bloodwork timing aligned with compound half-life
• Acknowledges the regulatory and clinical-evidence gap — SARMs are RUO, not approved drugs

The HL Supps position: both prohormones and SARMs are advanced compounds for informed athletes, not entry-tier supplementation. We provide them in the catalogue with full disclosure on cycle support, PCT, bloodwork, and regulatory status. The decision to use is the buyer's. The framework around how to use safely — that's the educational obligation we treat seriously.

Browse Mass Up → | Browse Best Boosters → | Read Pillar II: Testosterone, PCT & Cycle Support

E. Quality, Sourcing & Labeling

Q15. What's the difference between RUO and dietary supplement labeling?

The short answer: RUO (Research Use Only) is a legal classification for substances sold for laboratory work — not for human consumption. Dietary supplement is a regulatory category for products intended for ingestion to supplement the diet, with specific compositional and labeling requirements under EU Directive 2002/46/EC and national supplement laws.

Why the distinction matters legally:

Practical implications for the buyer:

Compounds typically sold as RUO:

• Research peptides (BPC-157, TB-500, GHK-Cu systemic, ipamorelin, CJC-1295, MOTS-c, epithalon, PT-141)
• SARMs (MK-2866, LGD-4033, RAD-140, GW-501516, SR-9009, S-23, YK-11)
• GLP-1 research compounds (semaglutide RUO, tirzepatide RUO — distinct from registered pharmaceutical forms)
• Investigational compounds in clinical development (orforglipron RUO, tesofensine RUO, BAM-15 RUO)

Compounds typically sold as dietary supplements:

• Mainstream — whey protein, creatine, BCAA, vitamins, minerals, omega-3
• Some "natural" performance compounds — turkesterone, ecdysterone, fadogia agrestis, tongkat ali
• Standard fat-loss compounds within EFSA limits (caffeine, green tea extract, L-carnitine)

Compounds in the grey zone:

• DMAA, DMHA, geranium extract, Eria Jarensis — banned as supplement ingredients in EU but sold under "advanced supplement / compound for informed athletes 21+" framing
• Yohimbine (allowed as ingredient but with strict labeling requirements)
• High-dose synephrine, ephedrine derivatives

The HL Supps labeling convention:

We use precise language by category to avoid the "fitness store calls everything a supplement" trap:

• Mainstream supplements: labelled as "dietary supplement" with EFSA-compliant claims
• DMAA / DMHA / ECA / yohimbine-heavy formulas: labelled as "advanced supplement / compound for informed athletes 21+"
• Prohormones: labelled as "compound for informed athletes 21+ / requires PCT"
• SARMs / research peptides: labelled as "Research Use Only — not for human consumption" with regulatory status disclosure

This isn't legal hair-splitting. It's how we maintain regulatory compliance across the EU while still offering the catalogue informed athletes need.

Q16. How do I read a Certificate of Analysis (COA)?

The short answer: A COA is the lab-confirmed identity, purity, and contamination profile of a specific batch of a compound. The four data points that matter most: identity confirmation method, purity by HPLC (or UPLC), contamination screen (heavy metals, residual solvents, microbiology), and batch number tied to your specific product.

What a real COA contains:

Red flags on a COA:

• No batch number — generic COA covering "all batches" is meaningless. The whole point is per-batch verification
• Identity by HPLC only (no MS, NMR, IR) — HPLC alone confirms presence of a peak at the right retention time, not that the peak is the right compound
• Purity stated as "≥99%" with no actual chromatogram — the chromatogram itself is what shows purity. A claim without the trace is unverifiable
• No third-party lab signature — in-house QC has obvious conflict-of-interest issues. Reputable suppliers commission third-party verification
• Issued date significantly before manufacturing date — COA should be issued post-synthesis on the actual batch, not a generic template predating the batch
• No impurity profile — every synthesis has byproducts. A COA showing zero impurities is incomplete or fabricated
• No heavy metals or residual solvent screen — for orally-consumed compounds these are non-negotiable
• For research peptides: no endotoxin testing — a problem for any peptide intended for in vivo research-route administration

The HL Supps own-brand COA standard:

For High League® branded products, every batch ships with a COA that includes:

• Batch number + date of manufacture + date of analysis
• Identity by MS or NMR (orthogonal to HPLC)
• Purity by HPLC ≥98% with chromatogram
• Heavy metals screen (ICP-MS)
• Residual solvent screen (GC)
• For peptides: endotoxin testing + bioburden
• Third-party lab signature (rotating between accredited EU labs)

These COAs are available as PDF on each product page (Quality & Certifications link). For third-party brands in our catalogue, we require the supplier to provide batch-matched COAs, which we make available on request.

Pharmacological Perspective — Dr. [PharmD]

"From a pharmacological standpoint, a COA is the only way to know what you're actually putting into a research model — or, in cases where that line gets crossed, into a person. The history of this industry has too many examples of mislabeled compounds, contaminated batches, and underdosed products. A reputable supplier shows you the data. If a product page or supplier email gives you a runaround on the COA — that's the signal."

Read more about our quality framework: Quality & Certifications →

F. Ingredient Status & Interaction Profiles

This section covers ingredients that turn up on mainstream supplement labels but carry a regulatory or interaction profile that does not fit on the label itself. Everything below is educational reference material — the same caveats as the rest of this page apply.

Q17. Is DHEA legal in EU dietary supplements?

The short answer: No. DHEA (dehydroepiandrosterone) is not permitted as an ingredient in dietary supplements in the European Union. In several member states it holds the status of a medicinal substance, dispensed only on prescription. It also appears on the WADA Prohibited List under category S1 (anabolic agents)¹³, which means it is prohibited in sport subject to anti-doping control.

The longer answer:

DHEA is an endogenous steroid — produced naturally in the human body, chiefly by the zona reticularis of the adrenal cortex and, to a lesser extent, by the gonads and the central nervous system. It circulates predominantly as the sulfated ester, DHEA-S.

Pharmacologically it is a precursor of androgens and estrogens: in peripheral tissues it is transformed into androgen and estrogen derivatives¹². That is why pharmacology classes it as a prohormone — a hormonally active substance acting on the androgen–estrogen axis, not an inert botanical.

Why it shows up anyway: DHEA is a legal dietary ingredient in the United States under DSHEA, so it appears on US-labelled products — multi-ingredient "test" formulas in particular — that reach the EU through cross-border sale. A US supplement label is not an EU authorisation. The status of a substance is decided by the law of the market where the product is sold, not by the label it was printed with.

Practical guidance:

• If you are subject to anti-doping control, treat DHEA exactly as you would any other S1 anabolic agent. It is prohibited at all times, in and out of competition.
• If DHEA is on a label you already own, treat the product as a prohormone, not as a natural testosterone booster — the bloodwork panel in Q8 and the fertility considerations in Q10 apply.
• The distinction between prohormones and non-steroidal compounds is covered in Q14; suppression and recovery are covered in our testosterone, PCT & cycle support guide.

Q18. Why is berberine under EU review, and what does ANSES say?

The short answer: Preparations containing berberine are the subject of a scientific assessment carried out at the request of the European Commission under Article 8 of Regulation (EC) No 1925/2006 — the procedure that allows a substance’s use on the EU market to be restricted or prohibited. The French agency ANSES states that the safety of using dietary supplements containing berberine cannot currently be guaranteed, and points to possible interactions with medications¹⁴.

The longer answer:

Berberine is an isoquinoline alkaloid found naturally in plants of the genus Berberis (barberry) — it is what gives their bark the intense yellow colour. It is not a novel synthetic: the regulatory attention it attracts is about dose and pharmacological activity, not about novelty.

What Article 8 actually is: a procedure under the Fortified Foods Regulation that the Commission opens when a substance added to food raises safety concerns. It can end in prohibition, in restriction to a maximum level, or in placing the substance under Union scrutiny. An open Article 8 assessment is not a ban — it means the question is live and the outcome can change what is legal to sell.

ANSES specifically advises against the use of berberine-containing preparations by children, adolescents, pregnant and breastfeeding women, and people in sensitive groups, and flags that berberine may affect the effectiveness of ongoing therapy.

Dihydroberberine (sold as GlucoVantage®) is a reduced — hydrogenated — derivative of berberine. It is a different molecule with a different absorption profile, but the same alkaloid backbone; the Article 8 assessment and the ANSES caution concern berberine preparations as a class, and a derivative does not sit outside that conversation by virtue of the name on the label.

Practical guidance:

• On any regular pharmacotherapy — consult a physician or pharmacist before using a berberine or dihydroberberine product. This is the single most important line in this answer.
• Berberine also turns up in cycle support stacks. Being an established stack ingredient is not the same as being a settled regulatory question.

Q19. Mucuna pruriens in a pre-workout — what does the L-DOPA content mean?

The short answer: Mucuna pruriens seeds are a natural source of L-DOPA (levodopa) — a dopamine precursor and, at the same time, the active substance in medications used in Parkinson’s disease¹⁵. A standardised extract in a pre-workout can deliver a pharmacologically meaningful amount.

The longer answer:

This is not a scandal and not a reason to panic — L-DOPA occurs naturally in the seeds, and the species has been the subject of clinical research. It is, however, a pharmacological fact you should know before you scoop, and the arithmetic is worth doing yourself:

• A label declaring 500 mg of extract standardised to 20% L-DOPA delivers roughly 100 mg L-DOPA per serving.
• A two-scoop serving of that same product delivers roughly 200 mg.
• If the label states only "Mucuna pruriens extract" with no standardisation figure, you cannot do this calculation — and that itself tells you something about the label.

Consult a physician before use if you take:

• Medications used in Parkinson’s disease (levodopa preparations, including combinations with carbidopa or benserazide) — stacking L-DOPA sources adds to the dose.
• MAO inhibitors, including antidepressants of that class — see also Q7.
• Antipsychotics — many act on the dopaminergic system.
• Blood pressure medications.

The same applies if you have a diagnosed neurological or psychiatric condition. If in doubt, show your physician the label together with the calculated L-DOPA content — a disclosed dose makes that a two-minute conversation instead of a guessing game.

Q20. Akkermansia muciniphila and the word "probiotic" — what is the EU status?

The short answer: In the EU, pasteurised Akkermansia muciniphila is authorised as a novel food (Implementing Regulation (EU) 2022/168), on the condition that live cells sit below the limit of detection¹⁶. Forms containing live cells are not covered by that authorisation. Separately, the European Commission treats the term "probiotic" itself as a health claim that has not been authorised.

The longer answer:

Two distinct regulatory questions get conflated here, so take them one at a time.

1. The organism. EFSA assessed pasteurised Akkermansia muciniphila as a novel food, and it was authorised on that basis. The pasteurisation is not incidental — non-viability is a condition of the authorisation. A product declaring a live-cell count (CFU) of this species is therefore describing a form that the EU authorisation does not cover. Consider the status of any specific product against the regulations of the market it is sold in.

2. The word. The EU register of nutrition and health claims contains not a single authorised claim for bacterial cultures — every application filed in that category has been rejected. The Commission’s position is that "probiotic" implies a beneficial health effect and therefore constitutes an unauthorised claim. Enforcement practice differs across member states: some permit the word conditionally, as the name of an ingredient category, with no accompanying health promise. That is the only sense in which it appears on this site — including on the probiotic supplements category itself, which is a catalogue heading and not a statement of effect.

Practical guidance: read a CFU declaration as a technical specification (how many colony-forming units of which strains), not as a health promise — because in the EU it cannot legally be the latter. How to read a batch specification is covered in Q16.

Q21. Is a "caffeine-free" pre-workout with paraxanthine actually stim-free?

The short answer: No. Paraxanthine is the primary metabolite of caffeine in the human body — an ingredient with stimulant character. A product can be truthfully labelled "caffeine-free" and still be a stimulant product. "Caffeine-free" and "stim-free" are not the same claim.

The longer answer:

After you drink coffee, hepatic CYP1A2 demethylates the bulk of the ingested caffeine — and paraxanthine (1,7-dimethylxanthine) is what most of it becomes. Dosing paraxanthine directly means starting at a point your body would otherwise have reached by metabolising caffeine. It is a distinct compound, not caffeine; it is not, however, a non-stimulant.

The label is not lying. "Caffeine-free" is a factual statement about the ingredient list. The gap is between what the label says and what a lifter hears — and a lifter hunting a genuinely stim-free formula for an evening session hears the wrong thing.

Paraxanthine as a standalone compound has been evaluated in human research at 200 mg — the amount typically declared in formulas that use it¹⁷. That describes the compound, not any given product.

Practical guidance:

• Count a paraxanthine product in your daily stimulant load, alongside coffee and any other stimulant supplements.
• Do not run it in the evening — the same reasoning as with any stim applies to sleep.
• If you want a formula with no stimulant ingredient at all, the stim-free pre-workout category is where to look — not a "caffeine-free" label.
• Tolerance behaves the way it does with any stimulant — see Q12 and our pre-workout tolerance breakdown.

Q22. Piperine (BioPerine®) — why does 5–10 mg matter?

The short answer: Because piperine inhibits P-glycoprotein and CYP3A4¹⁸ — the efflux transporter and the enzyme that between them handle the metabolism of a large share of medications. That makes a 5–10 mg "bioavailability enhancer" pharmacologically relevant out of all proportion to its dose.

The longer answer:

Piperine is the main alkaloid of black pepper (Piper nigrum) — what makes pepper pungent. BioPerine® is a standardised extract (95% piperine). It is added to formulas to raise the absorption of other ingredients, and it does that job by interfering with the machinery that clears xenobiotics. That mechanism does not distinguish between the ingredient you wanted absorbed and a medication you took an hour earlier.

This is the part worth internalising: the usual "is this dose big enough to matter?" instinct fails here. Ten milligrams of most things is a rounding error. Ten milligrams of a CYP3A4 inhibitor is a pharmacokinetic variable. The dose tells you nothing about the relevance.

Practical guidance:

• On regular pharmacotherapy of any kind — run any BioPerine®-containing formula past your physician or pharmacist. This includes formulas where piperine is a minor listed ingredient you would otherwise skim past.
• Where practical, leave a time gap between medication and a piperine-containing supplement.
• Check labels for it deliberately: piperine sits at the bottom of ingredient tables, at the smallest number on the panel — which is exactly where attention runs out.

Final Disclaimer

This Safety FAQ is educational reference material. It does not constitute medical advice, a clinical recommendation, or a personalised supplement protocol. The information here is based on published peer-reviewed research, regulatory guidance available at time of writing, and HL Supps internal expertise. Regulations change, new evidence emerges, and individual physiology varies — what's accurate at the date of this version may shift.

Before starting any supplementation protocol involving advanced compounds — DMAA, DMHA, geranium, ECA, yohimbine, prohormones, SARMs, research peptides — consult a physician, licensed pharmacist, or sports endocrinologist familiar with the compound class. The right clinician + bloodwork combination is worth more than any single supplement decision.

If you suspect an adverse reaction to any compound — discontinue immediately, hydrate, and seek medical evaluation. For acute cardiovascular symptoms (chest pain, severe arrhythmia, severe hypertension, sudden severe headache), seek emergency care.

Take the quiz: Which Stack Fits You? → for a guided assessment of which tier of supplementation matches your training experience, goals, and risk tolerance.

Download the ebook: The Advanced Athlete's Arsenal → for the full 48-page framework on stack architecture, PCT, and bloodwork for informed athletes.

References

1. Cohen PA, Travis JC, Keizers PHJ, et al. (2018). Four experimental stimulants found in sports and weight loss supplements: 2-amino-6-methylheptane (octodrine), 1,4-dimethylamylamine (1,4-DMAA), 1,3-dimethylamylamine (1,3-DMAA) and 1,3-dimethylbutylamine (1,3-DMBA). ↩
2. Sikiric P, Seiwerth S, Rucman R, et al. (2011). Stable gastric pentadecapeptide BPC 157: novel therapy in gastrointestinal tract. ↩
3. Wiehle RD, Fontenot GK, Wike J, et al. (2014). Enclomiphene citrate stimulates testosterone production while preventing oligospermia: a randomized phase II clinical trial comparing topical testosterone. ↩
4. Rahnema CD, Lipshultz LI, Crosnoe LE, et al. (2014). Anabolic steroid-induced hypogonadism: diagnosis and treatment. ↩
5. Ostojic SM. (2006). Yohimbine: the effects on body composition and exercise performance in soccer players. ↩
6. Boyer EW, Shannon M. (2005). The serotonin syndrome. ↩
7. Gillman PK. (2017). Monoamine oxidase inhibitors: a review concerning dietary tyramine and drug interactions. ↩
8. Robles-Diaz M, Gonzalez-Jimenez A, Medina-Caliz I, et al. (2015). Distinct phenotype of hepatotoxicity associated with illicit use of anabolic androgenic steroids. ↩
9. Tambi MIBM, Imran MK, Henkel RR. (2012). Standardised water-soluble extract of Eurycoma longifolia, Tongkat ali, as testosterone booster for managing men with late-onset hypogonadism?. ↩
10. Wilborn CD, Taylor LW, Campbell BI, et al. (2006). Effects of methoxyisoflavone, ecdysterone, and sulfo-polysaccharide supplementation on training adaptations in resistance-trained males. ↩
11. Isenmann E, Ambrosio G, Joseph JF, et al. (2019). Ecdysteroids as non-conventional anabolic agent: performance enhancement by ecdysterone supplementation in humans. ↩
12. Traish AM, Kang HP, Saad F, Guay AT. (2011). Dehydroepiandrosterone (DHEA) — a precursor steroid or an active hormone in human physiology. ↩
13. World Anti-Doping Agency. World Anti-Doping Code International Standard — Prohibited List (S1: Anabolic Agents). ↩
14. Agence nationale de sécurité sanitaire de l’alimentation, de l’environnement et du travail (ANSES). Use of berberine-containing plants in food supplements. ↩
15. Katzenschlager R, Evans A, Manson A, et al. (2004). Mucuna pruriens in Parkinson’s disease: a double blind clinical and pharmacological study. ↩
16. EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA). (2021). Safety of pasteurised Akkermansia muciniphila as a novel food pursuant to Regulation (EU) 2015/2283. ↩
17. Yoo C, Xing D, Gonzalez D, et al. (2021). Acute Paraxanthine Ingestion Improves Cognition and Short-Term Memory and Helps Sustain Attention in a Double-Blind, Placebo-Controlled, Crossover Trial. ↩
18. Bhardwaj RK, Glaeser H, Becquemont L, et al. (2002). Piperine, a major constituent of black pepper, inhibits human P-glycoprotein and CYP3A4. ↩
19. Bhasin S, Brito JP, Cunningham GR, et al. (2018). Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline.
20. Solimini R, Rotolo MC, Mastrobattista L, et al. (2017). Hepatotoxicity associated with illicit use of anabolic androgenic steroids in doping.
21. Solomon ZJ, Mirabal JR, Mazur DJ, et al. (2019). Selective Androgen Receptor Modulators: Current Knowledge and Clinical Applications.
22. Heffernan SM, Horner K, De Vito G, Conway GE. (2019). The Role of Mineral and Trace Element Supplementation in Exercise and Athletic Performance: A Systematic Review.