We’re told increasingly that we should increase our intake of fatty acids. But what are fatty acids, where do they come from and why are they supposed to be good for us?
Also known as polyunsaturated fatty acids (PUFA) Omega-3 and Omega-6 fatty acids are considered to be ‘essential fatty acids’ as they can’t be produced by the body and must be acquired through diet.
DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) Omega-3 fatty acids are found in salmon, herring, mackerel, anchovies and sardines, algae and krill. In addition, English walnuts and vegetable oils such as flaxseed/linseed, olive, canola, soybean contain the ALA (alpha-linolenic acid) type of Omega-3. A study carried out at Harvard University concluded that a lack of Omega-3 fatty acids in the diet is the 6th leading cause of preventable death in the U.S. and is likely to be responsible for between 72,000 and 96,000 deaths per year.
Symptoms of Omega-3 deficiency may include a dry scaly rash, poor memory, fatigue, heart problems, poor circulation, mood swings or depression, increased susceptibility to infection and poor wound healing. Part of the reason why Omega-3 fatty acids are so beneficial to the human body is that polyunsaturated fatty acids are a key component of the phospholipids that make up cell membranes. Omega-3s play a role in growth and vitality as they are involved in the metabolism of food to produce energy for cellular processes.
Omega-6 fatty acids exist in three forms: LA (linoleic acid), GLA (gamma-linolenic acid) and ARA (arachidonic acid). Linoleic acid is converted to gamma-linolenic acid (GLA) in the body. It is then further broken down to arachidonic acid (ARA). Sources of Omega-6 fatty acids include canola, safflower, flaxseed, maize, sunflower and soybean oils, walnuts, chia seeds, pumpkin seeds, flaxseed, salmon, halibut, mackerel, tuna and game meat including bison, elk and venison. Dairy products also contain Omega-6. Most Americans get plenty of Omega-6 fatty acids, but often this is of low quality, for example from foods cooked in vegetable oil.
The mucosa (intestinal lining) of the gastrointestinal tract acts as an interface for communication between the individual and the external environment. The mucosal surface has specialized structures for the chemical and immunological recognition of substances and organisms passing through it. Cells in the mucosa detect foreign substances and are instrumental in launching immune responses. In the healthy state, the vulnerable gut mucosa exhibits virtually no proinflammatory response to food antigens and contains very few hyperactivated immune cells.
Fatty acids can influence intracellular signaling processes and transcription factor activity and gene expression. This ability to impact cellular functions can affect physiological responses such as inflammation. The link between fatty acids and inflammation is that eicosanoids, which act as mediators and regulators of inflammation, are generated from arachidonic acid which is a breakdown product of Omega-6 fatty acids.
The mucosal damage which occurs in celiac disease is known to cause fat malabsorption and probably also affects the serum lipid profile. Interestingly, it has been found that adopting a totally starch-free diet results in much higher fat absorption, which can be as much as 15%.
The composition of the cell membrane fatty acids influences membrane permeability. In celiac disease the villi of the intestine are shortened and flattened, the crypt layer is increased in depth and the epithelial cells are damaged, compromising intestinal absorption. In addition, an inflammatory response takes place whereby vast numbers of immune cells congregate in the mucosa. Celiacs are therefore likely to be deficient in essential fatty acids due to their poor intestinal absorption, high requirement for tissue repair and increased conversion of Omega-6 essential fatty acids (EFA) into eicosanoids which can cause an inflammatory response.
Surprisingly, only 2 studies have been carried out which examined celiac disease and fatty acids. Unfortunately, they did not agree on which type of fatty acid was deficient! One study concluded that that there was a deficiency of Omega 3 fatty acids and the other concluded that there was a deficiency of Omega-6. But both studies concluded that celiacs are at risk of essential fatty acid deficiency.
A healthy diet contains a balance of Omega-3 and Omega-6 fatty acids. As mentioned above, Omega-3 fatty acids help reduce inflammation, and some Omega-6 fatty acids tend to promote inflammation. The typical American diet tends to contain 14-25 times more Omega-6 fatty acids than Omega-3 fatty acids, therefore it would seem that Omega-3 fatty acids are much more likely to be deficient.
Foods containing Omega-3 fatty acids are listed at the beginning of this article. Of these, flaxseed oil contains the highest amount of Omega-3, with only one tablespoon per day providing enough Omega-3 fatty acids for a slightly overweight adult. If the person is not taking flaxseed oil or eating oily fish at least twice a week, they could take supplemental fish oil, in capsule or liquid form. However, it is important to buy a high quality, molecularly distilled product, certified to be free of heavy metals and other contaminants, as some fish oils have been found to contain high levels of mercury.
Doses for Adults (18 years and older):
The NIH recommends eating oily fish at least two times per week and also plant-derived sources of α-linolenic acid, such as walnuts, flaxseed oil, tofu/soybeans and canola oil. The World Health Organization recommends taking 0.3-0.5 grams of daily EPA + DHA and 0.8-1.1 grams of daily α-linolenic acid.
Children of less than 18 years:
Effective doses have not been established for children, even though Omega-3 fatty acids are used in some infant formulas. Young children should only eat limited amounts of fresh fish due to the presence of potentially harmful environmental contaminants.