Supplements

Supplements are the part of longevity people most want to talk about, and the part that matters least. That doesn't make them useless. A few have good evidence for specific people. But no supplement makes up for poor sleep, no exercise or a poor diet, and most products marketed as "anti-ageing" have little human evidence behind them.

The right question isn't "what should I take?" It's "what is low, and what would fix it?"

Your body makes the best molecules

Most people look for health in something they can swallow. Some supplements genuinely help. But exercise, sleep and managing stress trigger your body's own chemistry, across many systems at once, in ways no pill can copy. That's why no supplement will ever replace training, sleeping or recovering well. Supplements can support a healthy life. They can't stand in for living one.

Food first, test second

Before buying anything, get a blood test (Level 2 in this course). Many supplements only help if you're deficient, and some, such as iron, can do harm if you're not.

Tier 1: well supported for many people

Vitamin D. Levels are low in many Northern Europeans, especially in winter. Test first: a target range of around 30–50 ng/mL (75–125 nmol/L) is commonly used. If you're low, your doctor can advise a daily dose based on your result.

Creatine monohydrate. One of the most studied supplements there is. 3–5 g a day supports the strength and muscle gains from training, and there's growing evidence for benefits to thinking, particularly under sleep deprivation and in older adults. Considered safe for healthy people at these doses.

Omega-3 (EPA and DHA). If you don't eat oily fish twice a week, a fish or algae oil helps fill the gap. An omega-3 index test shows whether you need it.

Protein powder. Less a supplement than convenient food, useful if you struggle to reach your protein target.

Tier 2: only when a number is red

• Psyllium fibre if LDL cholesterol or ApoB is high, or your fibre intake is low.
• Vitamin B12 if you're vegan, over 60, or take metformin or acid-reducing medication, and your level is low.
• Magnesium if your diet is low in nuts, seeds, legumes and whole grains. Some people find it helps their sleep.
• Iron only if a blood test shows you're deficient.

Tier 3: interesting, not proven

NAD+ precursors (NMN, NR), spermidine, resveratrol, fisetin and similar compounds have promising results in cells and animals, and very limited evidence in humans for anything related to healthy lifespan. Prescription drugs such as metformin and rapamycin are being studied for ageing, but they're not approved for it and they carry real risks. If you choose to experiment, know that you're experimenting, spend accordingly, and involve a doctor.

How to choose a product

• Look for third-party testing, such as Informed Sport or NSF Certified for Sport, especially for creatine, protein and fish oil.
• Avoid "proprietary blends" that don't list doses.
• Be wary of anything claiming to "reverse ageing".
• More is not better. Fat-soluble vitamins (A, D, E and K) can build up to harmful levels.

Safety

Supplements can interact with medication. St John's wort, high-dose fish oil, vitamin K and others affect common drugs. If you take any medication, are pregnant or breastfeeding, or have a health condition, check with your doctor or pharmacist before starting anything.

Please note
Food supplements are not a substitute for a varied, balanced diet and a healthy lifestyle.

This week

• List everything you currently take, and why.
• If you haven't had your vitamin D tested, add it to your next blood test.
• Stop anything you can't give a clear reason for taking.

In the journal

The journal doesn't track supplements every day. If a marker is red and you're taking something for it, "took my supplements" can be one of your seven boxes.

Sources: Kreider et al., Journal of the International Society of Sports Nutrition 2017 · Holick et al., Endocrine Society clinical practice guideline, 2011 · Bischoff-Ferrari et al., JAMA 2020