In this third and final installment of the role of macro-nutrients on the immune system, we are taking a look at the role dietary fat plays in immune response and function.
Fats are powerful mediators of the immune system, and they may modulate the immuno-suppressive effects of strenuous exercise. Dietary fat plays a role in some key functions in the body, which all contribute to immune function, namely:
- Hormone regulation and production, especially testosterone and oestrogen
- Transport of the fat-soluble vitamins (A, D, E and K), to the liver for storage and utilisation.
Dietary fats play an important role in numerous physiological functions and therefore a low fat diet can pose health problems. Additionally, a low fat diet does not guarantee weight loss if calories aren’t appropriate.
Both the amount and type of fatty acids in the diet influence the growth and activity of immune cells. Proper functioning of the immune system depends on adequate amounts of each essential fatty acid.
Essential fatty acids such as polyunsaturated fatty acids (PUFAs), are the precursors of substances that can promote or restrain inflammation. Essential fatty acids cannot be synthesized in the body and thus, must be taken in via the diet. Essential fatty acids are intricately involved in the immune response, and regulate cytokines, which are released from immune cells in response to injury, infection, or exposure to foreign substances, as previously mentioned in our protein and immunity article. Amongst the fatty acids those from fish oil (EPA and DHA) are more biologically potent than alpha linolenic acid.
Studies in athletes have shown that a low-fat diet (15% of total calories), increases inflammatory and decreases anti-inflammatory immune factors, depresses antioxidants, and negatively affects blood lipoprotein ratios. A critical analysis of a large number of studies, demonstrated that there is a number of potential benefits to consuming unsaturated fatty acids on the immune system. This analysis showed that fatty acids play an important role in immune system regulation and may therefore be classified as holding the ability to modulate immune response. http://www.nature.com/icb/journal/v78/n1/full/icb20006a.html
Increasing your omega 3 intake (specifically EPA), and decreasing your omega 6 and saturated fat intake can have positive health effects and decrease inflammation. Omega 3 sources include salmon, mackerel, eggs and red meat. Omega 6 sources include sunflower oil, corn oil and safflower oil.
• Saturated Fats: Usually solid at room temperature and are primarily from animal sources, such as, dairy and other meats.
• Unsaturated Fats: Usually liquid at room temperature and can be further divided into mono and poly unsaturated fats.
• Mono-unsaturated fatty acids include: olive oil, avocado and peanut butter.