Dietary Cod Protein May Help Prevent Type 2 Diabetes

Dietary cod protein improved insulin sensitivity in insulin-resistant individuals and could help prevent type 2 diabetes by reducing the metabolic complications related to insulin resistance, according to the results of a randomized, controlled trial. 

Véronique Ouellet, BSC, from the Institute of Nutraceuticals and Functional Foods, Laval University in Quebec City, Canada, writes that,  ""Studies in humans... showed that including lean fish, whose major component is fish protein, as opposed to other animal proteins, in a prudent-type hypolipidemic diet increased sex hormone–binding globulin and HDL2 [high-density lipoprotein 2] cholesterol concentrations, well-recognized parameters associated with insulin sensitivity." Thus, the objective of this study was to compare the effects of dietary cod protein with those of other animal proteins (beef, pork, veal, and milk) on insulin sensitivity in insulin-resistant men and women. Based on previous studies in animals and humans, we hypothesized that cod protein would improve insulin sensitivity in insulin-resistant subjects, compared with other animal proteins."

In a crossover design study, 19 insulin-resistant subjects were fed a cod protein diet and a similar diet containing lean beef, pork, veal, eggs, milk, and milk products (BPVEM) for 4 weeks. Both diets provided equivalent amounts of dietary fibers and monounsaturated, polyunsaturated (including n-3), and saturated fatty acids. A hyperinsulinemic-euglycemic clamp was used to determine insulin sensitivity, and beta-cell function was estimated from parameters derived from an oral glucose tolerance test.

Both controlled-feeding diets were associated with an average weight loss of 1 kg (1%). Compared with participants fed the BPVEM diet, those fed the cod protein diet had improved insulin sensitivity (P = .027) and a nonsignificant trend toward a better disposition index (beta-cell function X insulin sensitivity; P= .055).

After correction for median baseline insulin sensitivity (4.8 x 10–3 mg/kg/minute/pmol), there was an interaction between diet and insulin sensitivity status on the 30-minute C-peptide–to–30-minute glucose ratio, used as an index of beta-cell function (P = .022). There was a nonsignificant trend for this ratio to strongly increase in participants with low insulin sensitivity fed the cod protein diet vs those fed the BPVEM diet (P = .065).

• A previous study found that dietary protein derived from lean beef, lean fish, and poultry had similar beneficial effects on the lipid profile among men receiving a low-fat, high-fiber diet.
• In the current study by Ouellet and colleagues, consumption of cod protein improved insulin sensitivity and overall glucose homeostasis vs consumption of BPVEM.

Source: Diabetes In Control: Diabetes Care. Nov 2007;30:2816-2821