Two Provocative Papers on Diet and Health

People are always extremely interested in research on diet and health. Who would have thought that milk was so bad for you? Not only does milk increase risk of heart disease, but it aggravates the one condition that one might have supposed it would protect against, namely osteoporosis. Why doesn’t this high calcium drink prevent calcium loss from bone? The sugar in milk is lactose, a disaccharide derived from glucose and galactose. Galactose may be great for babies, but it is a powerful oxidant, and oxidants are harmful for adults. So it turns out milk aggravates osteoporosis leading to more fractures.[1] However, if you ferment the sugar to lactic acid, for example in producing yoghurt or soured milk, then these negative associations disappear. So the loss of bone in elderly people is not a calcium deficiency disease in most cases, and milk is positively harmful for bone maintenance. Most animals become lactase deficient, losing the ability to digest lactose after weaning.[2] This is not just an accident; it protects them from the harmful effect of galactose. For some reason humans are not so lucky and retain the enzyme. We therefore need to pre-ferment our lactose before consumption. Not surprisingly, a lively correspondence ensured after publication of this provocative paper, but the authors mount a convincing defence.

The question of what sort of diet to take to lose weight is a long-standing controversy – low carbohydrate or low fat? Well a recent randomised trial shows that a low carbohydrate option is much superior in terms of both weight loss and lipid profile.[3] I don’t think we should be surprised: very high carbohydrate diets are an anomaly that would not have occurred in human evolution before the relatively recent discovery of agriculture. It is a pity that the good Dr Atkins didn’t live to see his theory vindicated.

— Richard Lilford, CLAHRC WM Director

References:

  1. Michaëlsson K, Wolk A, Langenskiöld S, Basu S, Warensjö Lemming E, Melhus H, Byberg L. Milk intake and risk of mortality and fractures in women and men: cohort studies. BMJ. 2014; 349: g6015.
  2. Desai BB. Handbook of Nutrition and Diet. New York, NY: Marcel Dekker, Inc. 2000.
  3. Bazzano LA, Hu T, Reynolds K, Yao L, Bunol C, Liu Y, Chen C-S, Klag MJ, Whelton PK, He J. Effects of Low-Carbohydrate and Low-Fat Diets: A Randomized Trial. Ann Intern Med. 2014; 161(5): 309-18.
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