Osteoporosis is a condition whereby the bones of the body gradually lose mineral density and this leaves them susceptible to fractures. Women are more likely to develop osteoporosis than men, and risk increases greatly with age. Many studies have looked at the effects of calcium and vitamin D supplements on osteoporosis risk in both long term observational studies and in clinical trials, but the results have been inconsistent and inconclusive. However, many such studies used doses of calcium and vitamin D that are likely too low based on current understanding. More recently focus has shifted in osteoporosis research to investigating the role of plant foods in the development of the disease. In this regard plants are good sources of antioxidants such as vitamin E, and the protection that such phenolic compounds present to humans may inhibit a number of diseases including osteoporosis. Some evidence suggests that oxidative stress is an important mechanisms in age related loss of bone mass.
The effects of vitamin E have on the risk of bone fractures have been studied in older women in men. In one prospective study, researchers analysed the diets of men and women for the α-tocopherol isoform of vitamin E in two separate cohorts, and then followed the subjects for a number of years to assess their risk of bone fractures1. For women over a 19 year follow-up period, rates of bone fractures were significantly higher in those subjects who had the lowest intakes of α-tocopherol, compared to those with the highest intakes. In fact, the fracture rate in those with the lowest intake of α-tocopherol was almost twice (1.86 times) that in those with the highest intake. For men over a 12 year follow-up period, lower intakes of α-tocopherol were also associated with higher fracture rates (1.84 times) compared to the higher intakes of α-tocopherol. These results taken together suggest that the risk of hip fractures in elderly men and women is higher at lower intakes of the α-tocopherol form of vitamin E.
While these results are interesting and support the free radical theory of disease, it is difficult to assign cause and effect to the association between α-tocopherol and bone fracture rates. Animal studies do show that α-tocopherol supplements improve fracture healing rates, suggesting that vitamin E may indeed play a role in the prevention of fractures. However, the intakes of the subjects in this study were generally low and below the recommended intakes set for individuals in their country and so it is unclear as to the effect of higher concentrations of vitamin E. Of course it could be that vitamin E is simply a marker for a diet high in plant foods. Plant foods are the richest source of vitamin E and those who consume more plant foods have higher intakes of vitamin E. As plant food diets have been shown to benefit osteoporosis because they have an alkalising effect on the blood, which in turn decreases mineral resorption from bone, the nature of the diet as a whole rather than just vitamin E intake may the the defining factor here.
Dr Robert Barrington’s Nutritional Recommendation: It is unclear as to whether vitamin E is the cause of the reduced risk of fractures associated with its consumption. However, evidence does imply a causative effect for plant based diets on lower fracture rates. As vitamin E is required for antioxidant defences it is prudent to ensure that intakes are sufficient for optimal health. Eating a high quality plant based diet is best way to ensure adequate intakes of all the vitamin E isomers. Such diets will also likely protect from the acidification of the blood that is now thought to be a primary driver of osteoporosis, irrespective of the role played by vitamin E.
RdB
