Is Fish Oil Anabolic?

The recognition that omega-3 fatty acids are good for you came about when scientists compared the diet of native Inuit people to that of the Danish people. The Inuits ate a lot more fatty fish, rich in omega-3s, than the typical Dane. The early studies revealed that the Inuits had much lower rates of cardiovascular disease, which were traced to their high intake of omega-3 fatty acids from fish. Later studies showed that omega-3s lower blood triglycerides, which are a marker of cardiovascular disease. More important, omega-3 fatty acids exert powerful anti-inflammatory effects in the body—a huge benefit because out-of-control inflammation is now known to be the cornerstone of most major diseases, including cardiovascular disease, cancer, diabetes and brain degeneration.

One reason those diseases are so prevalent is that most people have an imbalance of fatty acids in their diets. Specifically, they eat far too many omega-6 fatty acids, the kind found in vegetables oils and other common foods, and not enough omega-3s, which are reliably found only in fatty fish. While linoleic acid, an omega-6 fatty acid, is considered essential in human nutrition, an excess of it leads to more inflammation in the body. That relates to the production of arachidonic  acid—itself the precursor of many types of inflammatory prostaglandins—from linoleic acid. You get a sense of just how potent that effect is when you realize that aspirin and anti-inflammatory drugs inhibit the enzyme that converts arachidonic acid into its inflammatory by-products, most of which are heavily involved in the body’s pain response.

An important point here is that people who don’t eat a certain amount of fatty fish each week are likely to be deficient in the active omega-3 fats, EPA and DHA. The alternative is to use fish oil supplements, which contain concentrated amounts of both EPA and DHA. The main controversy about the supplements is precisely how much to take. Some suggest that the more inflammation in the body, the higher the dose of fish oil you should take. Recent studies also suggest that high-dose fish oil may help reduce excess bodyfat, but that is a tale for another day.

Fish oil is a popular supplement among bodybuilders not only because of its documented health benefits but also because of a number of attributes more directly related to bodybuilding. Besides being an agent of increased fat burning, fish oil boosts the activity of antioxidant enzymes in the body, which would help prevent both premature exercise fatigue and excessive postworkout muscle soreness. In addition, fish oil provides vasodilation effects; it widens blood vessels in concert with increased nitric oxide production to improve oxygen delivery to working muscles, as well as lowering blood pressure. During training, fish oil helps maintain lower heart rates, thus reducing some of the burden exercise places on the heart. The one area where fish oil doesn’t seem to play a role is in triggering anabolic effects in muscle. A new study, however, may challenge that view.

As you age, your body tends to lose muscle and strength. Reasons for muscle loss vary, including decreased anabolic hormone flow—insulin, testosterone and growth hormone—and motor neuron activity. More recent studies also suggest that aged muscles show anabolic resistance, meaning that techniques that stimulate mass increases in younger people are blunted in older folks, starting around age 40. The effect is known as sarcopenia, which literally means “loss of muscle.”

When you provide amino acids in a high-insulin environment to younger people, you always get an anabolic effect. Because that effect is blunted in older people, they lose muscle. At the molecular level substances that play a vital role in muscle-protein-synthesis signaling just aren’t stimulated in older people, even when they get nutrients known to have a hand in it—amino acids. It seems that overall body inflammation increases with age, and that may interfere with important factors that signal muscle protein synthesis. It stands to reason, then, that if you could ease the higher inflammation typical of older muscles, you might be able to rejuvenate the blunted anabolic response.

That has actually been shown to happen. When older people are given anti-inflammatory drugs, such as ibuprofen, the usual anabolic resistance is decreased to the extent that they’re able to build muscle again. Ironically, the normal process of muscle growth involves a short period of high inflammation in the muscles after exercise. That inflammation, which is controlled by prostaglandins produced from arachidonic acid, is necessary to clear out debris in the muscle that could impede the process. It recedes in the young but remains chronic in older people, resulting in loss rather than gain of muscle.

Taking into account the fact that older people who take anti-inflammatory drugs appear to overcome the problem, what would happen if they took a natural anti-inflammatory substance—such as fish oil? That was the precise focus of a recent study.¹ Animal-based studies had already shown the effect. Growing steers given omega-3-rich menhaden oil increased the activation of muscle protein synthesis when they also got insulin and amino acids. Providing fish oil to burned guinea pigs—burns cause severe muscle catabolism, leading to a  great loss of body protein—kept the animals from losing muscle.

The new study involved 10 men and six women, all over age 60. All were in good health, none were obese, none were involved in regular exercise, and none used fish oil supplements prior to the experiment. They were randomly divided into two groups, with one group getting corn oil capsules, an omega-6 source, and the other a fish oil supplement that provided 1.86 grams of EPA and 1.50 grams of DHA. The dosages were chosen because they matched those used to lower elevated blood triglycerides in previous studies and were also similar to what had been given to animals that had shown an anabolic response. The older human subjects were given a clamp that produced high insulin, amino acid and glucose infusions and radioactive-tagged amino acids so the researchers could study the effects on muscle protein metabolism. The insulin and amino acid doses were comparable to the increased amount the body experiences after a meal.

The subjects who got the corn oil showed no effects. In those who used the fish oil supplements, there was no effect on muscle protein synthesis at rest, but with higher insulin and amino acids there was a significantly augmented effect. It was traced to a stimulation of muscle-protein-synthesis-signaling factors that went beyond the behavior of insulin and amino acids alone. The study suggests that taking fish oil would lessen the anabolic blunting effect of age. It would also help offset sarcopenia. Interestingly, the dose of fish oil used in the study did not affect markers of inflammation, suggesting that the anabolic effect it produced wasn’t related to inflammation control. The doses usually suggested for treating inflammation are far greater than those used in the study.

One question that arises in light of fish oil’s role in fighting blunted muscle protein synthesis in older people is whether it would have any effect on those under age 40. That question was recently answered by a study published by the same team of researchers who conducted the study of older people.² Nine subjects with an age range of 25 to 45 all received four grams of fish oil per day. The study found that the anabolic response to insulin and amino acids infusions was greater with fish oil supplementation. Specific factors involved in muscle protein synthesis increased by a whopping 50 percent after the subjects took fish oil.

—Jerry Brainum

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References

¹ Smith, G.I., et al. (2010). Dietary omega-3 fatty acid supplementation increases the rate of muscle protein synthesis in older adults: A randomized, controlled trial. Am J Clin Nutr. 93(2):402-32.

² Smith, G., et al. (2011). Omega-3 polyunsaturated fatty acids augment the muscle protein anabolic response to hyperaminoacidemia-hyperinsulinemia in healthy young and middle-aged men and women. Clin Sci. 121(6):267-78.