The last couple of decades have seen doctors place increasing emphasis on the diagnosis and treatment of the thinning bone disease known as osteoporosis. Public awareness of this condition is so great, it seems that practically every middle-aged or elderly female patient I see in practice asks me about it, whatever their primary complaint. One of their particular concerns is whether they are drinking enough milk. Despite the conventional wisdom that the calcium in milk is good for bones, I’ve always found it curious that Asian women whose diets are often quite bereft of milk tend to have stronger bones compared to their milk-drinking Western counterparts. Recently, I thought I’d bone up on the research to see if drinking milk really does help to protect against osteoporosis.

Despite its rather inert image, bone is in fact in a state of constant renewal – slowly but surely being broken down and built up again at about the same rate. Over time, if bone is undone more quickly than it is remade, then osteoporosis is the result. Osteoporosis is most common in women, particularly after the menopause when the bone-protective hormone oestrogen tends to be in short supply. The real risk for post-menopausal women is not the osteoporosis per se, but the fact that it increases the risk of potentially debilitating fractures such as those of the hip and the spine. Theoretically, feeding the bone with the nutrients that participate in its formation should help to stave off osteoporosis and reduce the risk of fracture.

As calcium is the predominant nutrient in bone, scientific eyes have traditionally focused on it as the major player in prevention of osteoporosis. Supplementation with calcium has indeed been shown to help bring small increases in bone density. Also, there is some research showing that drinking milk during childhood helps build better bones, and that the benefits may even persist into adulthood. However, the evidence that drinking milk in adulthood helps to strengthen bones is far weaker.

In a study published this month in the American Journal of Clinical Nutrition, researchers tracked the dietary habits and hip fracture rates in more than 72,000 women for 18 years. The results of this research found no relationship between the amount of milk and calcium women consume and their risk of fracture of the hip. In other words, drinking more milk does not seem to strengthen a woman’s bones. Much that this finding is somewhat counter-intuitive, it is not new: a previous review of the literature found that 12 of 14 studies examining the relationship between milk consumption and bone health found no association at all.

Women interested an alternative to cow’s milk might consider switching to soya milk. Soya is rich in oestrogen-like compounds called isoflavones that appear to help protect against osteoporosis. More than one study has found that increased soya consumption might actually increase bone density in time. Some scientists have suggested that the abundance of soya products in Asian women’s diets is a major reason for their apparent protection from osteoporosis. When mature female patients ask me about how to ward off osteoporosis, one suggestion I often give them is to use soya milk or soya yoghurt on their breakfast cereal in the morning, and maybe to add the occasional lump of tofu to a stir-fry or stew. I’m also keen to point out that the notion that drinking lots of dairy–derived milk is good for their bones looks like one sacred cow worth putting to rest.

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