Test First, Then Supplement

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Why clean eating doesn’t guarantee sufficiency

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It’s possible to do the fundamentals properly — real food, adequate sleep, consistent training — and still come up short on specific markers. That’s not a moral failure or evidence the fundamentals don’t work. It reflects a few structural realities: limited sunlight at northern latitudes for much of the year, declining mineral content in agricultural soil, and a food supply skewed heavily toward omega-6 fats.

The important consequence is that you cannot infer your own status from your diet quality. Two people eating nearly identically can have very different vitamin D levels depending on latitude, skin tone, and how much time they spend indoors. The only way to know is to measure, and then re-measure every 6–12 months, because what’s optimal at 40 isn’t necessarily optimal at 50.

Everything below is downstream of that. These are the compounds with reasonable evidence behind them — but which of them you need is a question only your blood work answers.

Creatine — the most studied, and not just for muscle

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Creatine isn’t a steroid. It’s a molecule your body already makes and that occurs in meat, though you’d need an impractical quantity of steak daily to reach a useful dose, and cooking degrades some of it.

At around 5g/day it supports strength, muscle growth, and recovery — this is the best-evidenced sports supplement in existence. The more interesting evidence concerns cognition: research at higher intakes, around 10g/day, points to cognitive benefits, particularly under sleep deprivation or mental fatigue. The effect sizes here are more modest and less consistent than the muscle findings, so treat it as promising rather than established.

Magnesium glycinate — 200–400mg at night

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Magnesium participates in hundreds of enzymatic processes, including nervous system regulation and muscle function. Intakes below recommended levels are common in Western populations.

The glycinate form matters practically: it absorbs well without the laxative effect that makes magnesium citrate unpleasant at useful doses. Taken at night, the commonly reported effect is easier wind-down after a demanding day rather than sedation.

Vitamin D3 — 2,000–4,000 IU, taken in the morning

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Vitamin D is functionally a hormone, synthesised in skin from UVB exposure. If you live at a northern latitude or spend most daylight hours indoors, insufficiency is likely for much of the year.

Two pairings worth knowing. Magnesium is required for the enzymes that convert vitamin D to its active form, so correcting magnesium supports vitamin D functioning. And as covered in the calcium-routing literature, vitamin D increases calcium absorption from the gut while vitamin K2 determines where that calcium is deposited — which is an argument against taking high-dose D in isolation.

Psyllium husk — the one with the hardest endpoint

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This is the least glamorous item here and arguably the best evidenced for something that matters.

Psyllium is a soluble fibre that binds bile acids in the intestine, increasing their excretion. The liver then has to synthesise replacement bile acids from cholesterol, which raises LDL receptor activity and pulls LDL out of circulation.

The numbers are real. A meta-analysis in the American Journal of Clinical Nutrition found a median dose of about 10.2g of psyllium reduced LDL cholesterol by 0.33 mmol/L, with parallel reductions in non-HDL cholesterol and apolipoprotein B — the latter being a better predictor of cardiovascular risk than LDL alone. Broader reviews put doses of 7–15g/day at roughly a 7% LDL reduction, appearing within three to four weeks.

Taken before a meal it also blunts glucose rise and reduces appetite, which is a secondary benefit rather than the main event.

Glycine — and a dose correction worth making

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Glycine before bed is genuinely effective, and the commonly circulated dose is higher than the evidence requires.

The trial work — Yamadera et al. (2007) — used 3g before bedtime in volunteers with mild sleep complaints, and found shortened sleep onset latency, improved sleep efficiency, reduced daytime sleepiness, and better performance on memory tasks. Recommendations of 5–10g are common online; the studied and effective dose is 3g.

The mechanism is temperature. Glycine acts on NMDA receptors in the suprachiasmatic nucleus, producing peripheral vasodilation and heat loss, which lowers core body temperature — the physiological signal that initiates sleep. That’s also why it doesn’t produce dependency or morning grogginess the way sedative hypnotics do.

At 3g it costs pennies per night.

Omega-3 — 1–2g combined EPA and DHA, kept cold

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The modern diet supplies abundant omega-6 from processed seed oils and comparatively little omega-3. Correcting that balance is associated with lower inflammatory markers and joint symptoms.

One handling detail does real work: refrigerate fish oil immediately after opening. Omega-3s oxidise at room temperature, and rancid oil is plausibly worse than none. If a capsule smells strongly of fish when opened, it’s already gone.

A greens powder is insurance, not food

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Worth being clear-eyed about. A greens powder or basic multivitamin is a hedge for travel days and weeks when eating gets chaotic. It doesn’t replicate vegetables — you lose the fibre, the food matrix, and most of the volume that makes vegetables filling. Reasonable as a backup; not a substitute.

Summary

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The supplements are secondary; the testing habit is the actual intervention. Blood work every 6–12 months tells you which of these you need, and prevents spending money on the ones you don’t. Where the evidence is strongest: psyllium at 7–15g/day lowers LDL by around 7% and reduces apolipoprotein B, and glycine at 3g — not the widely repeated 5–10g — shortens sleep onset and improves sleep quality by lowering core body temperature. Creatine at 5g is the best-studied performance compound, with more tentative cognitive evidence around 10g. Magnesium glycinate, vitamin D3, and omega-3 are worth correcting if measured low.

What to actually do:

1. Get blood work before buying anything — at minimum vitamin D, magnesium, a full lipid panel including ApoB, and ferritin.
2. Re-test every 6–12 months. Requirements change with age, season, and training load.
3. Use 3g of glycine, not 10g. That’s the studied dose, and the rest is waste.
4. Add psyllium if your LDL or ApoB is raised — 7–15g/day, expect movement in 3–4 weeks.
5. Refrigerate fish oil the day you open it.
6. Don’t copy anyone’s stack, including this one. The list is a menu; your results choose from it.

Nothing here is medical advice — if you take prescription medication, particularly anticoagulants or blood pressure drugs, check interactions with a pharmacist or doctor before adding supplements.

Sources & further reading

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• Jovanovski E. et al., Effect of psyllium (Plantago ovata) fiber on LDL cholesterol and alternative lipid targets, non-HDL cholesterol and apolipoprotein B: a systematic review and meta-analysis of randomized controlled trials, American Journal of Clinical Nutrition — AJCN
• Yamadera W. et al., Glycine ingestion improves subjective sleep quality in human volunteers / New therapeutic strategy for amino acid medicine: glycine improves the quality of sleep, Journal of Pharmacological Sciences — ScienceDirect
• Kawai N. et al., The sleep-promoting and hypothermic effects of glycine are mediated by NMDA receptors in the suprachiasmatic nucleus, Neuropsychopharmacology (2015) — Nature
• Psyllium supplementation and lipid profiles: systematic review and dose-response meta-analysis of randomized controlled trials, Genes & Nutrition (2025) — Springer
• Meta-analysis of usefulness of psyllium fiber as adjuvant antilipid therapy to enhance cholesterol lowering efficacy of statins, American Journal of Cardiology — AJC
• Sleep Foundation, Glycine for sleep: benefits, dosage and side effects — Sleep Foundation
• The effect of psyllium consumption on anthropometric indices: a systematic review and dose-response meta-analysis of randomized controlled trials — Springer