The overall goal of this study is to investigate the effects and the mechanisms of action of a fish peptide and vitamin D on glucose metabolism, insulin secretion, and cardiometabolic risk profile in overweight men. Transcriptomic and metabolomic approaches will be used to study the acute physiological effects of fish nutrients and to discover gene/metabolite networks that underlie these effects.

Sedentary lifestyle and excess calorie intake have contributed to a dramatic increase in the occurrence of obesity, metabolic syndrome (MetS), type 2 diabetes (T2D) and cardiovascular disease (CVD) The first step in reducing the excessive CVD risk associated with the presence of the MetS is the adoption of a healthier lifestyle. A balanced diet, including high-nutritive and low-energy foods such as fish, is an important component of a healthy diet. Fish is a major source of n-3 PUFA, high-quality protein, and other essential nutrients such as vitamin D. Fish consumption may therefore improve the components of the MetS and reduce the incidence of T2D and CVD in obese subjects.The foundation of this project stems from the well-recognized fact that few Canadians meet the weekly dietary recommendation for fish consumption (i.e. 2 servings/week) and thus intakes of both n-3 polyunsaturated fatty acid (PUFA) and fish protein are low in the general population, and even lower in obese subjects. Since some people simply dislike fish and because certain types of fish contain toxic contaminants, including heavy metals and environmental pollutants, fish consumption remains low. Therefore, dietary choices limit intake of its key nutrients, thus increasing risk for MetS, T2D and CVD. Also, fish is one of the richest food sources of dietary vitamin D which may also contribute to the health benefits of fish consumption. Indeed, it is currently estimated that ∼40% of Canadians have low serum 25-hydroxyvitamin D [25(OH)D] concentrations (≤50 nM) and that ∼70% are below 75 nM. In addition, obesity is an important risk factor for low serum 25(OH)D.The main objective of this study is to investigate the acute effects and mechanisms of action of fish peptide and vitamin D on glucose metabolism, parameters of insulin sensibility and secretion, and cardiometabolic risk profile in overweight men.

A four-arm randomized crossover design will be used to test the metabolic effects of consuming prior to a 3h-oral glucose tolerance test (OGTT), supplements containing either fish peptide (3 grams), vitamin D3 (1000 IU), a combination of fish peptide + vitamin D3 or a placebo.

Inclusion Criteria:

• overweight (BMI 25-40 kg/m2)
• fasting triglycerides ≥ 1.5 mmol/L
• fasting insulin ≥ 60 pmol/L
• non-smoking
• stable weight in the past 3 months

Exclusion Criteria:

• diabetes
• chronic diseases
• taking drugs that could affect glucose or lipid metabolism
• taking dietary supplements or natural health products
• major surgery 3 months prior to the study
• fish or seafood allergy
• lactose intolerance