A more alkaline diet may enhance the favorable impact of dietary protein on lean tissue mass in older adults

Authors: Dawson-Hughes, Bess; HARRIS, SUSAN - TUFTS/HNRCA; CEGLIA, LISA - TUFTS/HNRCA

Submitted to: American Society for Bone and Mineral Research
Publication Type: Abstract Only
Publication Acceptance Date: 6/15/2007
Publication Date: 9/15/2007
Citation: Dawson-Hughes, B., Harris, S.S., Ceglia, L. 2007. A more alkaline diet may enhance the favorable impact of dietary protein on lean tissue mass in older adults. American Society for Bone and Mineral Research Annual Meeting, 9/16/07-9/19/07, Honolulu, Hawaii. 22(1).

Interpretive Summary:

Technical Abstract: Maintaining muscle mass in aging is important to prevent falls and fractures. Dietary protein is required to preserve muscle mass, however the acid load from diets rich in acidogenic protein foods and cereal grains relative to alkalinogenic fruits and vegetables may contribute to loss of lean tissue mass in older adults. This analysis was conducted to determine whether for a given protein intake, a more alkaline diet has a more favorable effect on lean body mass (LBM). Subjects were 384 men and women age 65+ who participated in a 3-yr calcium and vitamin D versus placebo trial. All subjects gave written informed consent. Urinary nitrogen (N), an indicator of protein intake, and potassium (K) were measured at baseline in 24-hr collections. N was measured by the Dumas combustion method and K by direct-current emission spectroscopy. The N:K ratio, reflecting the ratio of acidic protein foods to alkaline fruit/vegetable intake, was calculated. LBM, defined as total body non-fat, non-bone tissue mass, was measured by DXA at baseline and 3 years. Physical activity, measured by Physical Activity Score for the Elderly (PASE) questionnaire, height, and weight were assessed at baseline and 3 years. At baseline, the mean N:K was 5.98 + 1.70 (SD) mmol/mmol. The N:K was inversely associated with baseline LBM (regression coefficient = -0.245, P = 0.011, adjusted for sex, age, weight, physical activity score, and nitrogen excretion) and with 3-yr change in LBM (regression coefficient –0.105, P = 0.046, adjusted in addition for treatment group and baseline LBM). These results suggest that the effect of protein on muscle may be enhanced when the overall diet is less acidic, that is, higher in fruit and vegetable content.