Supplements for men: which ones do you actually need?

Count what's in your kitchen cupboard. A multivitamin, a tub of magnesium, maybe fish oil, and a bag of protein powder somewhere at the back. Together that runs to roughly 200 to 400 euros a year, and for most of those tubs you don't actually know whether they do anything.

Here's something the supplement industry would rather you didn't hear. For most healthy men, the honest answer to "which supplements do I need" is surprisingly short. And you can largely read it off your blood.

That's the thinking error almost everyone makes: supplements aren't an upgrade, they top up a shortfall. No shortfall, nothing to top up.

Do you need supplements at all?

Most healthy men who eat a varied diet don't need supplements. The Dutch Voedingscentrum keeps it simple: with enough vegetables, fruit, wholegrains, fish and dairy you get nearly all your vitamins and minerals. Exceptions exist, but they're specific and usually visible in your blood.

In practice it works differently. You buy a tub because a mate takes it, because an ad landed, or because you feel tired. That's human.

It just isn't a plan.

According to the Voedingscentrum, most people have no reason to take a multivitamin by default. A large US review reached the same conclusion. Without a proven shortfall, there is little evidence that vitamins and minerals help prevent heart disease or cancer (PMID 24217421).

That isn't a reason to bin everything. It's a reason to know what you take and why.

Which supplements do I need as a man?

That depends on your blood, not on your sex alone. For men a few patterns do hold. Iron is rarely needed, vitamin D often runs low through a Dutch winter, and zinc and magnesium get taken in bulk on claims the research doesn't support.

What sets men apart from women: you don't lose blood through menstruation. That makes iron shortfall uncommon in men, and for that reason it's a signal when it does show up. Taking iron without a shortfall isn't risk free either.

So don't treat an iron pill as a harmless boost. It isn't.

We wrote earlier about why iron deficiency in men is rare but never simply normal.

Which supplement belongs to which blood value?

Nearly every popular supplement has a blood value that tells you whether you need it. That's the most useful thing I can hand you in this piece. Instead of guessing from a label, you look at the number underneath it. Here they are, with an honest evidence column.

Look at that right-hand column. Every row there is a measurable number, not a promise. That's the whole point.

Vitamin D: the supplement with the strongest Dutch basis

Vitamin D is the one supplement with broadly supported advice behind it in the Netherlands. You make it when sunlight hits your skin, and between October and March the sun sits too low here to make enough. So the value drops for many people over winter.

The Gezondheidsraad advises extra vitamin D mainly for specific groups, including people with darker skin, people who rarely get outside, and men from age 70. For a healthy 35-year-old who's outdoors regularly, that advice doesn't automatically apply.

What you can do: put your value in view instead of guessing. Vitamin D is one of the few supplements where the blood value shows directly whether taking it makes sense.

You can't put sun in a pill.

If you recognise complaints like fatigue or muscle weakness, read our piece on vitamin D deficiency in men. The same principle applies to B12, which we cover in vitamin B12 deficiency in men.

Zinc and testosterone: the most stubborn myth

Zinc raises your testosterone only if you're zinc deficient. In men with a normal zinc status, there's no good evidence that extra zinc pushes testosterone up. That makes zinc a fix for a shortfall, not an upgrade for a healthy man.

The classic research behind this comes from Prasad, who showed that a zinc-restricted diet lowered testosterone in young men, and that supplementing zinc-deficient older men raised it again (PMID 8875519). That's a deficiency story, not a booster story.

Yet zinc sits as the headline ingredient on almost every testosterone booster. I find that plainly misleading, because it leans on an effect that only exists in men who don't have it.

The full explanation, including who in the Netherlands genuinely runs a risk of low zinc, is in our piece on zinc and testosterone. Magnesium has a similar story, covered in magnesium and muscle cramps.

Magnesium: why the blood value is tricky

Magnesium is the supplement men expect the most from, and the one the ordinary blood value says the least about. Roughly 1 percent of all the magnesium in your body sits in your blood. The rest is in your bones and your cells, and your body holds that blood value stubbornly steady.

That has an awkward consequence. A normal serum magnesium doesn't fully rule out a shortfall in your tissue. It's one of the few minerals where the standard measurement gives you only part of the story.

That's why, alongside magnesium in the blood, there's also intracellular magnesium, which looks inside the cell rather than around it. If you have complaints while your serum value reads normal, that can be a more useful angle.

What I see a lot of men do: take magnesium for cramp or poor sleep, without ever having measured anything. Sometimes it helps. Often you simply don't know whether the pill was the reason.

Creatine and protein: the two that really move your blood values

Creatine and protein powder are the two sports supplements that can visibly change your blood result without anything being wrong. Creatine raises your creatinine, and protein raises your urea. Both look alarming on paper and usually aren't.

Creatine is one of the best-researched supplements in sports nutrition. The International Society of Sports Nutrition concluded that use of up to 5 grams a day is well tolerated in healthy people (PMID 28615996). The strength and muscle gain is small but real.

The catch is in the name. Creatine, the supplement, differs by one letter from creatinine, the waste product your kidneys clear. Take creatine and more of it breaks down into creatinine, so your measured value rises.

Your kidneys are not filtering worse. One letter, a lot of panic.

That one letter causes men needless panic every year. The full explanation, plus the kidney marker that doesn't get distorted, is in creatine and your blood values.

Protein has a different ceiling. A meta-analysis by Morton found that extra protein above roughly 1.6 grams per kilo of bodyweight per day adds barely any further muscle growth (PMID 28698222). Most men already reach that from ordinary food. How much you actually need is covered in protein shakes: how much protein do you actually need.

Omega 3: what fish oil does and doesn't do

Fish oil reliably lowers your triglycerides, by around 15 percent. What it does not demonstrably do is lower your chance of a heart attack. That's an uncomfortable gap between what the label suggests and what the large trials show.

The Cochrane review on omega 3 and cardiovascular disease did find that triglyceride drop, but barely any effect on hard outcomes (PMID 32114706). Two large trials with more than 41,000 participants between them landed on the same picture.

My conclusion after reading those studies: fish oil is a tool for your fats, not a shield for your heart. Whether it does anything for you shows up in your triglycerides. That saves a lot of guessing.

More on that in what fish oil really does to your blood values.

Eating little or no meat? The odds shift

Vegetarians and vegans do run a higher risk on a few fronts. Vitamin B12 occurs naturally in animal products almost exclusively. Zinc and iron from plants are also absorbed less well, because phytates in grains and pulses hold back absorption.

For B12 the story is clearest. If you eat no animal products at all, supplementing is practically unavoidable according to the Voedingscentrum, because you get it from nowhere else.

Zinc is subtler. You do take it in through nuts, pulses and wholegrains, but you absorb a smaller share of it. Your zinc status can therefore land lower than your plate would suggest.

If you eat plant-based and want to know where you stand, the Vegetarian panel looks at the values that go with that eating pattern. This is exactly the case where measuring beats guessing.

Which supplements can you skip?

The multivitamin is the most redundant purchase in the average kitchen cupboard. In people without a demonstrated deficiency, there's no convincing evidence it prevents disease. Testosterone boosters with herbal blends are a second category where the evidence is almost always thinner than the marketing.

An iron supplement without a demonstrated deficiency belongs on this list too. Deficiency is uncommon in men, and excess iron accumulates in your organs. It's one of the few supplements where "I'll take it just in case" is genuinely unwise.

What the RIVM and the Voedingscentrum keep repeating is that lifestyle remains the foundation. Enough movement, not smoking, going easy on alcohol and a healthy weight do more for your blood values than any tub.

That's dull. It's also true.

How do you know if you're actually deficient?

By measuring instead of guessing. Vitamin D, vitamin B12, ferritin, zinc and magnesium are all ordinary blood values. They tell you whether the tub you unscrew every morning is topping something up, or whether you're producing expensive urine.

Take two men of 38 who both take a daily multivitamin. One has a vitamin D value of 32 nmol/l after a long winter, the other sits at 78 nmol/l. Same pill, completely different meaning. Only the first is actually topping anything up.

If you want your vitamins and minerals in view, the Basic Health Checkup looks at a number of these values. If you're specifically after the B vitamins, the B-Vitamins panel is more targeted. For the wider picture including hormones, there's the Complete Men's Health Panel.

My advice stays simple. Measure first, supplement second, bin the rest. Discuss an unusual result with your GP, who can help you decide whether further steps make sense.

References

• Voedingscentrum. Vitamins and minerals: do I need supplements? 2024. voedingscentrum.nl
• Gezondheidsraad. Evaluation of the dietary reference values for vitamin D. gezondheidsraad.nl
• RIVM. Dutch national food consumption survey: intake of vitamins and minerals. rivm.nl
• Fortmann SP, et al. Vitamin and mineral supplements in the primary prevention of cardiovascular disease and cancer. Ann Intern Med. 2013. PMID 24217421.
• Kreider RB, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation. J Int Soc Sports Nutr. 2017. PMID 28615996.
• Morton RW, et al. Protein supplementation and resistance training-induced gains in muscle mass and strength. Br J Sports Med. 2018. PMID 28698222.
• Abdelhamid AS, et al. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2020. PMID 32114706.
• Prasad AS, et al. Zinc status and serum testosterone levels of healthy adults. Nutrition. 1996. PMID 8875519.

Every blood test result at Caliber includes a professional assessment by a BIG-registered doctor. For treatment decisions, always discuss your results with your GP.