Vitamin D, B12 and calcium: which supplements have earned their place after 60

A confession from someone who writes about nutrition for a living: I take two supplements, and I have spent a fair proportion of my career explaining to people why the other forty in their cupboard are doing nothing. The evidence base for supplementation in well-nourished adults is, with a few specific exceptions, a long record of promising observational findings that did not replicate.

The exceptions are worth knowing precisely because they are exceptions.

Vitamin B12: the one that genuinely changes with age

This is the strongest case on the list, and the mechanism is specific rather than vague. Absorbing B12 from food requires stomach acid to release it from the protein it is bound to, and then intrinsic factor to carry it across the ileum. Both decline with age. Atrophic gastritis — thinning of the stomach lining with reduced acid production — affects a substantial minority of adults over sixty, and long-term proton pump inhibitor or metformin use compounds it.

The consequence is that older adults can be eating plenty of B12 and absorbing very little of it. Deficiency presents as fatigue, cognitive changes, and peripheral neuropathy — pins and needles, unsteadiness — and the neurological damage can become permanent if it goes on long enough.

The useful detail is that the absorption problem applies to food-bound B12. Crystalline B12, as found in supplements and fortified foods, does not require the same liberation step and is absorbed reasonably well even with low stomach acid. Which is why several national bodies, including the US Institute of Medicine, recommend that adults over fifty obtain B12 from fortified food or a supplement rather than relying on meat and dairy alone.

It is water-soluble, cheap, and has no established toxicity at normal doses. If you take one thing from this article, take this one.

Vitamin D: real, and oversold in both directions

Vitamin D has had a strange decade. Observational studies linked low levels to almost everything — cancer, cardiovascular disease, dementia, autoimmune conditions, infections — and the large randomised trials that followed, principally VITAL and D-Health, found essentially none of it. Supplementing vitamin D in generally replete populations does not prevent cancer, does not prevent cardiovascular events, and does not reduce all-cause mortality.

That is a genuine and important negative result, and it has not filtered through to the supplement market at all.

What remains is narrower and still real. Vitamin D is necessary for calcium absorption and bone mineralisation; deficiency causes osteomalacia, which is a real disease with real fractures. Older adults are at elevated risk of deficiency for several converging reasons: skin synthesis falls with age, time outdoors falls with age, and those in residential care may get almost no sun exposure at all.

So the sensible position is supplementation for insufficiency rather than for benefit. Most guidelines suggest 400–800 IU (10–20 µg) daily for older adults, and considerably more only where deficiency is documented. High intermittent doses — the annual or monthly mega-dose approach — have been associated with increased falls in at least two trials, which is a striking result and a good argument for daily modest dosing.

Calcium: food first, and be careful with the pills

Calcium requirements rise modestly after menopause and in later life. Most guidance lands around 1,000–1,200 mg a day for older adults.

The complication is that calcium supplements — as opposed to dietary calcium — have been associated in some analyses with a small increase in cardiovascular events, and with kidney stones. The evidence is contested and the effect, if real, is modest. But since dietary calcium carries no such signal, the reasonable order of preference is clear: dairy, fortified plant milks, tinned fish with bones, tofu set with calcium sulphate, and leafy greens first; supplements only to close a measured gap.

Two-thirds of a litre of milk gets you most of the way there. So does 200 g of yoghurt plus a fortified plant milk on cereal.

The ones with weaker cases than their sales suggest

Omega-3. The large trials — VITAL, ASCEND, STRENGTH — have been largely negative for cardiovascular prevention at typical doses. REDUCE-IT found benefit with high-dose purified EPA in a specific high-triglyceride population, which is a pharmaceutical result, not an argument for fish oil capsules generally. Eating oily fish twice a week remains a good idea for reasons that go beyond the omega-3 content.

Multivitamins. The COSMOS-Mind substudy found a small cognitive benefit that generated a lot of headlines and needs replication. Broadly, multivitamins in well-nourished populations have not shown mortality or major disease benefit. They are harmless and, for someone with a genuinely poor diet, arguably a reasonable safety net.

Collagen, glucosamine, turmeric, resveratrol, NMN. Ranging from "modest effect in some knee osteoarthritis trials" to "interesting in mice". None has evidence justifying its price.

The interaction nobody mentions

Supplements are not inert. High-dose vitamin E increases bleeding risk with anticoagulants. St John's wort induces liver enzymes and reduces the effectiveness of a long list of drugs. Calcium and iron interfere with the absorption of several antibiotics and with levothyroxine. High-dose fish oil adds to antiplatelet effects.

Take everything you swallow — prescription, over-the-counter and herbal — to your next medication review, in the actual packets. It is the fastest way to find out whether one of your supplements is quietly undermining one of your drugs.