The supplements worth the money, and the ones worth stopping

People bring me carrier bags. Genuinely — a structured medication review quite often involves a supermarket bag of tubs, most of which were started after an article, and none of which anyone has revisited since.

So here is the short version.

Worth taking

Vitamin D, between October and March, for almost everyone in the UK. At this latitude you cannot make enough from sunlight through the winter, and deficiency is common and genuinely symptomatic. Ten micrograms a day. It costs a few pounds a year and there is no need for the expensive versions.

Folic acid, 400 micrograms daily, if you could become pregnant. Start before conception, not after a positive test, because the neural tube closes in the fourth week when many people do not yet know.

B12, if you eat no animal products at all. This one is not optional and the deficiency is slow, silent and eventually irreversible.

Iron, only if a blood test has shown you need it. Not on spec. It is constipating, it interferes with other medicines, and in people who are not deficient there is no benefit at all.

Worth stopping

Multivitamins, for anyone eating a broadly ordinary diet. Large trials have looked for a benefit repeatedly and not found one.

High-dose antioxidants — beta-carotene and vitamin E in particular — where the evidence runs the wrong way. Beta-carotene supplementation increased lung cancer rates in smokers in two separate trials.

Most of the joint supplements. Glucosamine and chondroitin have been studied extensively and the effect, if any, is smaller than the effect of the exercise you would do instead.

The honest caveat

“No good evidence of benefit” is not the same as “harmful”, and a supplement you find useful at a few pounds a month is not a crisis. What I object to is the sixty-pound-a-month bag, taken in place of something that would work, by someone who has never had it reviewed.

Bring the bag. We will go through it.