🍊 Vitamin C

Vitamin C (ascorbic acid) is a water-soluble vitamin that helps protect cells and supports the skin, blood vessels, bones, cartilage and wound healing. Adults need about 40 mg a day, while a cup of cow’s milk (240 ml) has only about 5 mg, so milk is not an important source of this vitamin.

The body does not store vitamin C, so you need to get it every day (NHS). The best sources are citrus fruits and their juice, peppers, strawberries, blackcurrants, broccoli, Brussels sprouts and potatoes. A lack of the vitamin leads to scurvy.

Vitamin C is the only vitamin in milk that is noticeably destroyed by heating, writes the FDA. During pasteurisation at 72 °C for 16 seconds, according to the studies in a review, about 15–17% is lost (5% in goat’s milk), and heating to 90 °C for 10 minutes reduces it by about 70%. After milking, light and oxygen also spoil the vitamin, so storage conditions may matter more than pasteurisation.

According to the FAO, camel milk is richer in vitamin C than cow’s milk; for people in dry regions where fruit and vegetables are scarce, it is an important source. The FAO does not specify how much.

Vitamin C or ascorbic acid? Ascorbic acid is vitamin C, a water-soluble vitamin. Milk or fruit and vegetables? Here the difference is large: a cup of cow's milk (240 ml) has only about 5 mg, roughly an eighth of the 40 mg adults need daily, while citrus fruits, peppers, strawberries, blackcurrants and broccoli are the best sources. Raw milk or pasteurised? Vitamin C is the one vitamin in milk noticeably destroyed by heating, though light and oxygen after milking also spoil it, so storage may matter more than pasteurisation.

Do not look for vitamin C in the dairy chiller: a cup of cow's milk gives about 5 mg, so go to the fruit and vegetable section of a supermarket for citrus, peppers, strawberries, broccoli and potatoes. On labels the vitamin may appear as ascorbic acid. “Pasteurised” on a milk pack means gentle heating (about 72 °C for 16 seconds in the studies cited), which costs about 15–17% of the vitamin. For supplements, the NHS says more than 1000 mg a day may cause stomach pain and diarrhoea.

Why it matters to you. Do not count on milk as a source of vitamin C: a cup provides only about an eighth of the daily 40 mg. An excess from supplements is not desirable either: the NHS writes that more than 1000 mg a day may cause stomach pain and diarrhoea. Milk is valued for other things, calcium and vitamin B12, so get vitamin C from fruit and vegetables.