Calcaneum broadband ultrasound attenuation relates to vegetarian and omnivorous diets differently in men and women: an observation from the European Prospective Investigation into Cancer in Norfolk (EPIC–Norfolk) population study

Abstract

Vegetarian diets have been suggested to be beneficial for bone health due to increased consumption of plant foods, including soya, or reduced consumption of meat. However, meat may also be beneficial for bone health. The evidence relating diet to bone health is based largely on studies of women, often in those at high risk of osteoporosis. Few studies have investigated dietary inter-relationships in men as well as women from general populations. We examined broadband ultrasound attenuation (BUA) of the calcaneum, using a CUBA clinical instrument, in 6,369 men and 5,379 postmenopausal women. The population was divided into four groups according to vegetarian status and frequency of soya consumption, which was defined by response to a food frequency questionnaire that estimates frequency of consumption of food types over the year prior to completion. Regular soya consumers were defined as those who ate soya products with a frequency of between once a day and once a week. Calcaneum BUA in vegetarian men was significantly lower than omnivores by approximately 6% (5 dB/MHz) and was 15% (13.6 dB/MHz) lower in those who were also regular soya consumers. This difference remained after adjustment for age, height, weight, smoking habit, physical activity, selected foods and nutrients and exclusion of those with a prior history of osteoporosis, fractures or cancer. Calcaneum BUA in omnivorous men with regular soya consumption was not lower than the remaining population. In women, there were no significant differences by usual dietary pattern. This surprising finding indicates that regular soya intake is not associated with better bone indices in vegetarian men. The difference in BUA was not explained by the known common covariates; however, it is possible that other aspects of lifestyle associated with these eating behaviors might explain this observation. Plausible mechanisms exist for our findings; soya contains phytoestrogens, likened to naturally occurring estrogens, and meat has been shown to influence levels of IGF-1 and sex hormone binding globulin, which may be related to bone health. Our findings emphasize the need for further research and investigation into dietary inter-relationships and bone health and the effects of vegetarian status, including consumption of soya-based foods, in men as well as women.