By Dr. Lee Stoner
Open the kitchen cupboard of most men over 40 and you will find six or seven bottles, bought at different times, for reasons nobody can quite remember. Fish oil. Vitamin D. Magnesium. Something for the joints.
Supplements vs diet is one of the most searched questions in men’s health, and the honest answer has less to do with which bottle you pick than with one thing almost nobody checks. The large trials that tested these pills recruited tens of thousands of people who were, for the most part, already eating well enough. In the biggest survey of American adults to look at this, ever having used a dietary supplement was not linked to living any longer.1 The US Preventive Services Task Force reached the same place after pooling 84 trials and nearly 740,000 people: little or no benefit for preventing cancer, heart disease or death.2
A supplement works when it fills a gap. It does very little when there is no gap to fill.
| What you will work out | What you can do with it |
|---|---|
| Why most supplement trials come back empty | Stop reading “no effect” as “it failed for everyone” |
| Which of the popular supplements have real trial evidence | Spend money on two or three, not seven |
| What food does that capsules do not | Change three things on the plate this week |
Will a supplement actually make me feel better?
Here is the part the labels never explain. A nutrient supplement is a correction, not an upgrade. If your blood level of something is low, topping it up can change how you function. If your level is already fine, adding more mostly gives you expensive urine, and the trials show exactly that.
Take the VITAL trial, which randomised 25,871 older adults to vitamin D, omega-3, or placebo for a median of 5.3 years. One gram of fish oil a day did not lower major cardiovascular events, 386 cases against 419 on placebo, and did not lower cancer either.3 Vitamin D in the same trial did produce one genuine result, fewer confirmed autoimmune diseases, 123 cases against 155.4 The Australian D-Health trial then gave 21,308 adults a monthly dose for up to five years and found no difference in cancer at all.5
Magnesium makes the pattern obvious. Across 38 trials in 2,709 people, magnesium lowered systolic blood pressure by about 2.8 mmHg on average. In people with normal blood pressure, nothing. In people already on blood pressure medication, 7.7 mmHg, and in people with low blood magnesium, 6.0 mmHg.6 Same capsule, different men, completely different answer.
Which supplements are worth my money after 40?
The table grades the popular ones against their strongest trial evidence. Two things are worth noticing before you read it. First, the multivitamin worry runs the opposite way to the rumour: in pooled trials, multivitamin use came out with slightly lower cancer incidence, not higher, and the real harm signal in that same review belongs to beta-carotene, which raised lung cancer risk in people already at high risk.2 Second, the friendliest glucosamine number comes from an analysis whose authors reported large uncertainty around every estimate they produced.7
Read the last column as a question about you rather than about the pill. Every verdict in it flips the moment a blood test shows you are actually short of something.
| Supplement | Best evidence | Verdict for a man who is not deficient |
|---|---|---|
| Fish oil (omega-3) | VITAL, 25,871 adults, 1 g/day, 5.3 years: 386 vs 419 major cardiovascular events | Eat the fish instead |
| Vitamin D | VITAL: fewer autoimmune diseases, 123 vs 155. D-Health, 21,308 adults: no difference in cancer | One real benefit, modest; test first |
| Magnesium | 38 trials, 2,709 people: 2.8 mmHg lower systolic overall, nothing in men with normal blood pressure | Worth it if your blood pressure or magnesium is low |
| Zinc | Cochrane, 34 studies, 8,526 people: does not prevent colds; may shorten one by about two days, low certainty; more minor side effects.8 | Only while you have a cold, if at all |
| Vitamin B12 and other B vitamins | Cochrane, 15 trials, 71,422 people: no effect on heart attack or death, small reduction in stroke.9 | Only if you are deficient |
| Glucosamine | 47 trials, 22,037 patients with knee osteoarthritis: small pain benefit, with large uncertainty around every estimate | Weak, and only if your knees already hurt |
| Multivitamin | 84 studies, 739,803 people: slightly lower cancer incidence, no benefit for heart disease or death | Harmless insurance, not a health plan |
What should I change on my plate instead?
This is where the evidence gets stronger, not weaker. The same American survey that found no mortality benefit from supplements did find that adequate vitamin A, vitamin K, magnesium, zinc and copper were linked to lower death rates, and the link held only when those nutrients came from food.1 Fibre tells the same story: across 185 studies and 58 trials, the highest fibre eaters had 15 to 30 per cent lower death rates, with the sweet spot between 25 and 29 grams a day.10
The strongest test of a whole way of eating remains PREDIMED, which put 7,447 people at high cardiovascular risk onto a Mediterranean diet with extra-virgin olive oil, the same diet with nuts, or a low-fat diet. Both Mediterranean groups had fewer heart attacks, strokes and cardiovascular deaths.11 Pull in the other direction and the picture is just as clear: higher intake of ultra-processed food carries a 50 per cent higher rate of death from cardiovascular disease.12
| More of | Less of |
|---|---|
| Fibre, aiming for 25 to 29 grams a day from beans, whole grains, vegetables and fruit | Ultra-processed food, the biggest single win on this list |
| Extra-virgin olive oil and nuts as your main fats | Calcium supplements taken on top of an already adequate diet |
| Oily fish, the food version of the capsule that did not work | Bottles bought for symptoms you have never had measured |
The takeaway on supplements vs diet
You do not need to throw the cupboard out. You need to change the question. Instead of asking which supplement to buy next, spend a fortnight fixing the plate, then ask your GP to measure the two or three things worth measuring. If something is low, fill that one gap. If nothing is low, the money is better spent on olive oil, beans and a decent piece of fish.1
“The question is not which pill to buy. It is what your diet is actually missing, and almost nobody has checked.”
SciencEye
Leave a Reply