Journal Name:
Nutr. J.
Article Title:
An increase in dietary n-3 fatty acids decreases a marker of bone resorption
Date Written:
2007
Volume:
6
Number:
2
Page:
1
Author(s):
Griel, AE.; Kris-Etherton, PM.; Hilpert, KF.; et al
Article:
Recent evidence suggests that omega 3 polyunsaturated fatty acids (PUFAs) may be beneficial in bone health. Bone is a dynamic tissue that is constantly being reshaped by osteoblasts, which build bone, and osteoclasts, which resorb bone. Animal and in vitro research has found that omega 3 PUFAs inhibit the activity of osteoclasts and enhance the actions of osteoblasts. It therefore appears that sufficient quantities of dietary omega 3�s may inhibit bone resorption and promote bone formation. The present study represents the first controlled feeding trial in humans which evaluated the effects of dietary plant-derived omega 3 PUFA on bone turnover, assessed by serum concentrations of N-telopeptides (NTx) and bone-specific alkaline phosphatase (BSAP). NTx and BSAP are measures of bone resorption and formation, respectively.
Twenty-three subjects (male=20; female=3) participated in this randomized, double-blind, three-period crossover design study. Subjects were overweight (mean BMI = 28.1 +/- 0.7) and mildly hypercholesterolemic (baseline mean total cholesterol = 5.85 +/- 0.12 mmol/L). Each dietary period lasted 6 weeks and was separated by a 3 week compliance break where participants consumed their usual diets. Three test diets were used: 1) Average American Diet (ADD; 34% total fat, 13% SFA, 13% MUFA, 9% PUFA (7.7% LA, 0.8% ALA); 2)); 2) Linoleic Acid Diet (LA; 37% total fat, 9% SFA, 12% MUFA, 16% PUFA (12.6% LA, 3.6% ALA)); 3) Alpha-linolenic Acid Diet (ALA; 38% total fat, 8% SFA, 12% MUFA, 17% PUFA (10.5% LA, 6.5% ALA)). Walnuts and flaxseed oil were the predominant source of ALA. Subjects consumed either breakfast or dinner at the diet center Monday through Friday and all other meals were prepared and packed for offsite consumption. Serum samples were obtained at baseline and at the end of each dietary period for subsequent analysis.
The results indicated that mean NTx concentrations at the end of each experimental diet were 15.59 +/- 1.21, 13.80 +/- 1.21, and 13.20 +/- 1.21 nM BCE for the AAD, LA and ALA diets, respectively. A significant reduction in NTx levels following the ALA diet was observed, with a similar trend noted for the LA diet, when compared to the ADD diet, indicating a decrease in osteoclast, or bone resorption, activity. There were no observed changes in BSAP (indicator of bone formation) across the three diets.
These results suggest that incorporating ALA rich foods into the diet may exert a protective effect on bone metabolism by decreasing bone resorption with a concurrent maintenance of bone formation. Thus, increasing dietary intake of plant based omega- 3 PUFA may provide health benefits not only to the cardiovascular system, but also to the skeletal system., ,
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