The Effect of Caloric Restriction with and without n-3 PUFA Supplementation on Bone Turnover Markers in Blood of Subjects with Abdominal Obesity: A Randomized Placebo-Controlled Trial.

Weight loss contributes to an increased risk of hip fracture, especially in postmenopausal women. Omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation could diminish the adverse effect of weight loss on bone health. The aim of this randomized, placebo-controlled, double-blind parallel trial was to investigate the effect of caloric restriction and n-3 PUFA supplement intake on osteogenic markers (carboxylated osteocalcin (Gla-OC); procollagen I N-terminal propeptide (PINP)), as well as a bone resorption marker (C-terminal telopeptide of type I collagen (CTX-I)) in a serum of 64 middle aged individuals (BMI 25-40 kg/m2) with abdominal obesity. Bone remodeling, metabolic and inflammatory parameters and adipokines were determined before and after 3 months of an isocaloric diet (2300-2400 kcal/day) or a low-calorie diet (1200 kcal/day for women and 1500 kcal/day for men) along with n-3 PUFA (1.8 g/day) or placebo capsules. CTX-I and adiponectin concentrations were increased following 7% weight loss independently of supplement use. Changes in CTX-I were positively associated with changes in adiponectin level (rho = 0.25, p = 0.043). Thus, an increase in serum adiponectin caused by body weight loss could adversely affect bone health. N-3 PUFAs were without effect.

Effect of caloric restriction with or without n-3 polyunsaturated fatty acids on insulin sensitivity in obese subjects: A randomized placebo controlled trial.

BACKGROUND: Caloric restriction and n-3 polyunsaturated fatty acid (PUFA) supplementation protect from some of the metabolic complications. The aim of this study was to assess the influence of a low calorie diet with or without n-3 PUFA supplementation on glucose dependent insulinotropic polypeptide (GIP) output and insulin sensitivity markers in obese subjects. METHODS: Obese, non-diabetic subjects (BMI 30-40 kg/m(2)) and aged 25-65 yr. were put on low calorie diet (1200-1500 kcal/day) supplemented with either 1.8 g/day n-3 PUFA (DHA/EPA, 5:1) (n = 24) or placebo capsules (n = 24) for three months in a randomized placebo controlled trial. Insulin resistance markers and GIP levels were analysed from samples obtained at fasting and during an oral glucose tolerance test (OGTT). RESULTS: Caloric restriction with n-3 PUFA led to a decrease of insulin resistance index (HOMA-IR) and a significant reduction of insulin output as well as decreased GIP secretion during the OGTT. These effects were not seen with caloric restriction alone. Changes in GIP output were inversely associated with changes in red blood cell EPA content whereas fasting GIP level positively correlated with HOMA-IR index. Blood triglyceride level was lowered by caloric restriction with a greater effect when n-3 PUFA were included and correlated positively with fasting GIP level. CONCLUSIONS: Three months of caloric restriction with DHA + EPA supplementation exerts beneficial effects on insulin resistance, GIP and triglycerides. GENERAL SIGNIFICANCE: Combining caloric restriction and n-3 PUFA improves insulin sensitivity, which may be related to a decrease of GIP levels.