More fish fatty acids, more IGF-1

A diet that is relatively high in fish fatty acids is not only healthy, but also ergogenic. It raises the concentration of the anabolic hormone IGF-1 in the blood, according to an animal study

at Texas Tech University, in which the researchers were actually trying to determine the anabolic effects of fish fatty acids on the skeleton.

Fish fatty acids contribute to a slimmer body by stimulating fat burning and inhibiting the build up of fat reserves. These effects have been shown in animal studies, test tube studies, experiments and human trials. From experiments on people with cancer we now know that fish-oil makes protein supplementation more effective and animal tests suggest that a diet containing fish oil helps muscle tissue to recover more quickly after training.

The Texans discovered yet another reason for athletes to take relatively higher doses of omega-3-fatty acids when they carried out an experiment in which they gave middle-aged rats a high-fat diet for twenty weeks. A fifth of the diet consisted of fats. The researchers gave one group mainly n-6 fatty acids, another group n-6 and n-3 fatty acids, and one group mainly n-3 fatty acids.


Bone mass declines as ageing progresses. This also happened to the rats. The speed at which the rats lost bone mass was however clearly lower in the fish-oil group [n-3] The table below shows how this happened. The n-3 diet raises the concentration of a series of anabolic hormones in the blood. We have highlighted the one that is most interesting for athletes.


A higher protein intake also leads to higher concentrations of IGF-1. Perhaps fish fatty acids and proteins work synergistically, and raise muscle manufacture levels together via IGF-1.

Protective effect of dietary long-chain n-3 polyunsaturated fatty acids on bone loss in gonad-intact middle-aged male rats.


This study evaluated the effect of a fat blend containing long-chain (LC) n-3 PUFA on bone mineral density (BMD) and bone metabolism in gonad-intact middle-aged male rats (12 months old, n 28). Seven rats were killed on day 0 of dietary intervention to determine the baseline BMD. The remaining rats (seven per group) were fed a diet with one of the following dietary lipid treatments (g/kg diet): 167g safflower oil+33g menhaden oil (N6+N3 diet, control), 200g safflower oil (N6 diet, almost devoid of LC n-3 PUFA), or 190g menhaden oil+10g corn oil (N3 diet, rich in LC n-3 PUFA) for 20 weeks. After 20 weeks, all dietary treatment groups had a lower BMD compared with the baseline reference. However, rats fed the N3 diet had the highest bone mineral content and cortical+subcortical BMD compared with those fed the N6 and control N6+N3 diet. Compared with the control (N6+N3) group, rats fed the N3 diet had higher values for serum insulin-like growth factor-I, parathyroid hormone, 1, 25-(OH)2 vitamin D3 and bone-specific alkaline phosphatase activity, but lower bone NO production and urinary Ca, whereas rats fed the N6 diet had higher bone prostaglandin E2 production and serum pyridinoline. These findings indicate a protective action of LC n-3 PUFA on ageing-induced bone loss in gonad-intact middle-aged male rats through a modulation of local factors and systemic calcitrophic hormones.