N05046: Nutrition and bone health in men and women

Study Duration: January 2003 to December 2005

Contractor: University of Cambridge

Bone health is a major public health issue. Osteoporotic fractures are an increasing clinical and public health problem. Annually, 50,000 hip, 40,000 wrist and 130,000 vertebral fractures occur in Britain. Hip fracture numbers are projected to increase to 120,000 annually by the year 2020. Ninety percent of hip fractures occur in those aged 65 years and over, and a quarter of these in men. A vast proportion of hip fractures, the most serious osteoporotic fracture, are primary. Most research has focussed on secondary prevention, or very high risk groups and has mainly been in women. However, primary prevention of osteoporotic fractures in both men and women must be a high priority. Diet is thought to play an important role in bone health; small changes in diet in the population may have a big impact on bone health and fractures.

In this study, the role of specific nutrients and foods in bone health for which there is a lack of robust data, will be examined using a combination of best available dietary intake measures (7 day diary) and biochemical nutrient status. In particular, a range of antioxidants and fatty acids (retinol, lycopene, lutein, alpha and gamma tocopherol, alpha and betacarotene, beta-, cantha- and zea-xanthin; oleic, alpha-linoleic, linoleic, C15:0, C20: and C22: series) not available in any previous population studies of bone health and fracture providing data in men as well as women, will be assessed. We will be able to compare estimates from food frequency (the instrument used in most diet studies) with those from 7-day diaries. We will estimate the potential renal acid load (PRAL) and Net Endogenous Acid Production (NEAP).

The central hypothesis is that diet has demonstrable effects on bone health and fracture risk in the general population. The main aim is to identify the specific dietary patterns (nutrients, foods and patterns of intake) that influence bone health and fracture risk. Specific hypotheses to be tested include:

i. High intake of plant foods is associated with a) higher bone heel ultrasound measures and b) lower fracture rates. This may be mediated through a number of nutrients in plant foods including vitamin C and vitamin K which we will assess using blood biomarkers and nutrient databases.

ii. A diet with a low acid/base balance estimated using PRAL and NEAP is associated with a) higher bone heel ultrasound measures and b) lower fracture rates. We will compare the independent contributions of animal and non-animal protein in any associations.

iii. High fish intake is associated with a) higher bone heel ultrasound measures and b) lower fracture rates and this is mediated through higher levels of omega 3 fatty acids (validated by blood fatty acid biomarkers)

iv. Dietary patterns that influence bone heel ultrasound measures and fracture occurrence have similar effects in men and women.