miércoles, 29 de marzo de 2017

Macronutrients, Exercise and Immunology Part 2: Lipids

As was discussed part 1, exercise can depress the function of the immune system. Supplementing with carbohydrate during exercise has been shown to blunt this response therefore the immune system can function better than if no supplementation had taken place. In this post, we will be looking at the role of fatty acids in exercise and immune function.

As with carbohydrate, the main role of fatty acids is a source of energy. As well as energy, certain fatty acids are involved in inflammation and immune responses. A dialogue that is probably very familiar to all of us is that Omega-6 fatty acids are pro-inflammatory and Omega-3 anti-inflammatory and that our modern diet has too much Omega-6 and not enough Omega-3. Just a quick google search of either Omega-3 or 6 will result in many nutrition “experts” giving advice on how to improve the ratio of the fatty acids in the diet. 

The Omega-6 linoleic acid is termed an essential fatty acid because, as with essential amino acids, it cannot be synthesised by the body and therefore must be obtained through the diet. Nuts, seeds and vegetable oils are rich sources of linoleic acid1. Once in the body, linoleic acid can be converted to another Omega-6 fatty acid arachidonic acid, this fatty acid is a pre-cursor to inflammatory mediators known as prostaglandins and leukotrienes. These two mediators are involved in inflammatory (and allergic) reactions, hence the belief that a diet rich in Omega-6 can lead to problems associated with chronic inflammation. Despite their role in inflammation, the authors of the exercise and immunology review2 state that currently there is no strong evidence to support the claims that altering your Omega-6 intake will affect inflammation. In terms of the role of Omega-6 in exercise and the immune system, the same authors state that there is very little research in this area.

Moving on to the Omega-3 fatty acids EPA and DHA, the anti-inflammatory actions of these fatty acids, taken as either a fish oil supplement or as oily fish, are well documented. EPA and DHA can be easily assimilated into cell membranes at the expense of the Omega-6 arachidonic acid, which of course leads to less production of the prostaglandins and leukotrienes. They are also involved in the production of mediators that resolve inflammation, enhance immune function and regulate key signalling events within immune cells such as T-cells and B-cells.

Unlike with Omega-6, the role of Omega-3 within exercise is a well-researched topic. However, (there is always a however) it is difficult to draw any firm conclusions from the published research. A large difference in doses used, (1g – 4g/day), the populations studied (untrained or elite athletes) and length of time of the studies (one week to several months) have made it difficult to say with confidence that Xg of Omega-3 taken per day will help you decrease exercise induced immunodepression. Supplementing with Omega-3 appears to decrease post exercise muscle soreness and exercise induced inflammation in untrained individuals but the evidence in trained and elite individuals is less convincing. The conclusion of the authors of the Exercise and Immunology Review is that more research is needed in this area.

So, what conclusions if any can we draw from this information? Regardless of its role in exercise Omega-3 fatty acids have numerous health benefits, so I would recommend that our diet has sufficient Omega-3 in it, either by ensuring we eat 1-2 portions of oily fish per week, or if you do not eat fish, take a fish oil supplement. At this moment in time I would avoid taking large doses of Omega-3 either before or during exercise until there is stronger evidence supporting the claim that it has a beneficial effect in this area. 

If you want any more information on diet, exercise and the immune system please get in touch via wayne@gabinetederueda.es 

1. http://nutritiondata.self.com/foods-000141000000000000000-w.html   
2. Berman S et al. (2017) Immunonutrition and Exercise Consensus Statement. Exercise and Immunology Review: Vol 23

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