Nutrition and Aging

Ageing is a universal human experience and we still understand its causes poorly. What we do understand reasonably well is how to reduce the damage it does — and a surprising share of that is nutritional.

When I first wrote this a decade ago I gave the standard advice of the time. Two things have changed enough since then that the article needed rewriting rather than refreshing.

The protein recommendation is too low, and everyone knows it

The official RDA for protein is 0.8 g per kilogram of body weight per day, for every adult regardless of age. That figure is now widely regarded as inadequate for older adults, and the reason is a phenomenon called anabolic resistance: an ageing muscle responds less to the same amount of protein than a young one does. The same meal builds less muscle.

An international expert group reviewed this and recommended 1.0 to 1.2 g/kg/day for healthy older adults, and 1.2 to 1.5 g/kg for those who are acutely or chronically ill.¹ For a 70 kg person that is roughly 70–85 g a day rather than 56 g — a meaningful difference, and one most people miss without noticing.

Sarcopenia is now a diagnosis, not a description

The gradual loss of muscle mass and strength with age used to be treated as an inevitable background fact. It is now a recognised condition with formal diagnostic criteria, and the important change is that low muscle strength, rather than low muscle mass, is the primary marker.²

That matters because strength is what determines whether you can get out of a chair, carry shopping, or recover from a fall. It is also modifiable at any age. The single most effective intervention is resistance training — and it works in people in their eighties and nineties, not just the newly retired.

If you find yourself avoiding stairs, struggling out of a low chair, or gripping jar lids with difficulty, those are not simply signs of getting older. They are worth raising with your doctor, because they are treatable.

Vitamin B12: the absorption problem

Older adults commonly have adequate B12 in the diet and inadequate B12 in the blood. The reason is that the stomach produces less acid with age, and stomach acid is required to release B12 from the protein it is bound to in food.

Two further groups are at higher risk regardless of age: people on long-term metformin, and people on long-term acid-suppressing medication. Both are extremely common after 60.

The practical consequence is that B12 from fortified foods or a supplement — which is not protein-bound and does not need acid to be released — is absorbed more reliably than B12 from meat. This is one of the few places where I actively recommend a supplement, and I say why in the supplements article.

Vitamin D, without overclaiming

Vitamin D is where the guidance has shifted most, and mostly in the direction of restraint. The large randomised trials found no reduction in cancer, cardiovascular events or fractures in adults who were not deficient to begin with.

What current guidance does support is extra vitamin D for specific groups, and adults over 75 are one of them. For everyone under 75 without a defined indication, the recommended daily allowance is enough and routine blood testing is not recommended. The detail, with the reference, is in the supplements article.

The things that actually change with age

• Energy needs fall; nutrient needs do not. Fewer calories must carry the same vitamins and minerals, which makes nutrient density — not portion size — the governing idea after 65.³
• Thirst becomes unreliable. The sensation weakens with age, so dehydration arrives without warning. Drink to a schedule rather than to thirst, particularly in hot weather or during illness.
• Calcium and vitamin D matter more, because bone loss accelerates and a fracture at 80 is a different event from a fracture at 40.
• Appetite and taste change, and medications frequently make it worse. Unintentional weight loss in an older adult is never simply ageing — it warrants a conversation with a doctor.
• Fibre and fluid together handle the constipation that so often follows reduced mobility and multiple medications.

Plant-based eating and long life

The population that has taught us most about diet and longevity is a religious one. Seventh-day Adventists in California live substantially longer than their neighbours, and the Adventist Health Study-2 — about 96,000 people followed for decades, across the whole range from vegan to regular meat-eater — is where most of what we know about long-term plant-based eating comes from.

Vegetarians in that cohort had roughly 12% lower all-cause mortality than non-vegetarians, with pescovegetarians lowest of all.⁴ Body weight and diabetes prevalence fell along the same gradient.⁵ These are lifelong patterns rather than diets adopted at 60, which is part of why the signal is so clear.

Two practical points follow for older readers specifically.

Vegetarian patterns can meet protein needs, but not by accident. Analyses of the Adventist cohort found vegetarian diets generally higher in fibre, magnesium, potassium, folate and vitamins A, C and E, and lower in saturated fat — but lower in protein and B12, the two nutrients this article has spent the most time on.⁶ That combination is close to ideal for an older adult provided protein is deliberately covered by legumes, soya, nuts and dairy or eggs if eaten, and B12 is supplemented.

The gradient means partial change counts. Nobody in these data had to become vegan to benefit. The semi-vegetarian and pescovegetarian patterns did well, which is a far more realistic target for someone changing how they eat at 70.

What has not changed

A predominantly plant-based pattern remains the best-supported way to eat at any age: low in saturated fat, high in fibre and potassium, rich in the antioxidants and phytochemicals that isolated supplements have repeatedly failed to reproduce. Five servings a day of fruit and vegetables is as sound a target at 75 as at 35.

The difference after 65 is simply that you have less room for error — fewer calories to work with, and a body less forgiving of shortfalls. That argues for eating well deliberately rather than by luck.