Vitamins: what they do and where to find them

Vitamins A, D, E and K dissolve in fat, are absorbed with the fat in a meal and are stored in the liver and fat tissue, so large doses can build up. The B vitamins and vitamin C dissolve in water and the body stores little of them, except vitamin B12, which the liver holds for years.

Mostly, from a varied diet, with two common exceptions. Vitamin B12 occurs naturally only in animal foods, so vegans need fortified foods or a supplement, and few foods contain vitamin D, which the skin makes in sunlight.

Yes. Multivitamins, single-vitamin supplements and fortified foods are sources too, and the total from food and supplements together is what counts toward the daily amount and the upper limit.

Yes, almost always from supplements. Adults should stay under 3,000 mcg a day of preformed vitamin A (retinol) and 100 mcg (4,000 IU) of vitamin D, the upper limits set by both EFSA and the US National Academies.

In US surveys, most adults get less vitamin D and vitamin E from food than they need, and many fall short on vitamins A and C. Worldwide, the WHO counts vitamin A deficiency as a leading cause of preventable blindness in children.

Some of them. Vitamin C, thiamin and folate break down with heat and leach into cooking water, so steaming or microwaving keeps more than boiling. Vitamins A, D, E and K hold up better.

Caltide adds up every vitamin except biotin from the foods you log and the supplements you tick, and shows each one against the amount for your age and sex in the Nutrition tab.