CALCIUM IN MILK

New Zealand Listener, Volume 10, Issue 244, 25 February 1944, Page 3

CALCIUM IN MILK

Sir,-In The Listener of January 21 on Page 21 is the statement that "there is a huge amount of calcium in milk as compared with other foods." May I be permitted to challenge his statement? There is only one part of calcium in 600 parts of milk, which is thus not rich in calcium. Spinach, cabbage, lettuce, onions and radishes all contain more calcium per cent of weight than milk does.-

F.

STONE

(Epsom).

This letter was referred to Dr. Muriel Bell, who says in reply: "The usual values given by authorities of recent date for the amount of calcium in 100 grams (approximately 31 oz.) of the fresh foods mentioned by the writer are in the vicinity of 118 milligrams for milk, 80mg. for spinach, 40 to 60mg. for cabbage, 30 to 40mg. for onions, 17 to 54 mg. for lettuce, 31 to~ 43mg. for radishes. Occasionally, figures go up to 400 to 600mg. for greens e.g., the outer leaves of cabbage sometimes analyse out at over 400, and English figures for spinach are recorded at 595. But people do not usually use the outer leaves of cabbage; and as for spinach, the figures are always annotated to the effect that the calcium in spinach is not nutritionally available (the presence of oxalic acid causes precipitation of calcium oxalate in the intestine; thus, little if any of the calcium becomes absorbed). It is chiefly, however, the amounts of vegetables that we consume that makes them rank so much lower than milk; e.g., the average intake of milk in New Zealand is about 2-3 pint, or 400 grams, while the usual helpings of spinach, cabbage or onions are about 100 grams, and of lettuce or radishes, about 50 grams. It is comparatively easy to take a pint of milk (which provides you with practically all the calcium you need per day), but in order to obtain the same amount of calcium from the vegetables mentioned by the writer, it would be necessary to consume about 21lb. of spinach (even if all the lime in it were available), or about 4lb. of onions, radishes or lettuces, or 3lb. of cabbage or 30z. of cheese. Of these I should think that the pint of milk or even the 3oz. of cheese would be more comfortable, the alternative leading, as Drummond puts it, to a ‘sensation of frustration and wind.’ Figures per equal weights of foods are apt to be misleading. Moreover, the body absorbs a given amount of calcium more easily from milk than from any other food."