Influence of moderate energy restriction and seafood consumption on bone turnover in overweight young adults

• Published in: The American journal of clinical nutrition 2008-04, Vol.87 (4), p.1045-1052
• Main Authors: Lucey, Alice J, Paschos, George K, Cashman, Kevin D, Martínéz, J. Alfredo, Thorsdottir, Inga, Kiely, Máireád
• Format: Article
• Language: English
• Subjects: 25-hydroxycholecalciferol; 25-hydroxyergocalciferol; Adult; Analysis of Variance; Animals; Biological and medical sciences; biomarkers; Biomarkers - blood; Body Mass Index; Bone and Bones - drug effects; Bone and Bones - metabolism; bone density; Bone Resorption - prevention & control; bone turnover; Clinical trials; Diet, Reducing; Dietary Supplements; Effects; Feeding. Feeding behavior; Female; fish; Fish oils; Fish Oils - pharmacology; food intake; Fundamental and applied biological sciences. Psychology; Gadiformes; Humans; Linear Models; low calorie diet; Male; men; nutritional intervention; Obesity; Osteocalcin - blood; overweight; Overweight - diet therapy; Overweight - metabolism; Plant Oils - pharmacology; Salmon; Salmonidae; Seafood; seafoods; Sunflower Oil; Treatment Outcome; Vertebrates: anatomy and physiology, studies on body, several organs or systems; vitamin D; Vitamin D - analogs & derivatives; Vitamin D - blood; Weight control; Weight Loss; women; Young adults
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/87.4.1045

BACKGROUND: Overweight and obesity are increasing in young adults. However, moderate energy restriction aimed at lowering body weight may promote bone turnover and bone loss. Inclusion of fish or fish oils in a weight-loss diet may attenuate these adverse skeletal effects. OBJECTIVE: We examined the effects of incorporating fish or fish oil into an energy-restricted diet on bone turnover markers in young overweight adults. DESIGN: While following a strict hypoenergetic (-30% relative to estimated requirements) diet for 8 wk, 276 overweight men and women [body mass index (in kg/m²): 27.5-32.5; age: 20-40 y) were randomly assigned to 1 of 4 dietary groups: sunflower-oil capsules (3 g/d; control), cod (3 x 150 g/wk), salmon (3 x 150 g/wk), and fish-oil capsules (3 g/d). Body weight, bone biomarkers, and 25-hydroxyvitamin D were measured at baseline and endpoint. Data were analyzed with repeated-measures analysis of variance and general linear models. RESULTS: The mean (±SD) weight loss was 5.14 ± 3.0 kg (5.8% ± 3.2% body weight) during the 8 wk in the 4 dietary groups combined. Urinary N-telopeptides of type I collagen and serum C-terminal telopeptide of type I collagen increased (P < 0.05), whereas serum osteocalcin (but not bone-specific alkaline phosphatase) decreased (P < 0.05) from baseline to endpoint. Increased fish or fish-oil consumption had no effect (P > 0.1) on the changes in bone markers induced by weight loss. In contrast, increased salmon consumption increased serum 25-hydroxyvitamin D (P < 0.01). CONCLUSIONS: A nutritionally adequate but energy-restricted diet, with different contents of n-3 fatty acids, which resulted in modest weight loss, unfavorably altered bone turnover markers in young overweight adults. Such changes were not prevented by increased fish or fish-oil consumption. This trial was registered at the US National Library of Medicine as #NCT00315770.