What are Omega-3 and Omega-6?
Out of the 20 fatty acids needed by the body, all of them are made from either:
- Omega-3 i.e. α–linolenic acid or ALA (also termed n−3 fatty acids or ω−3 fatty acids) or,
- Omega-6 i.e. linoleic acid or LA (also termed n−6 fatty acids or ω−6 fatty acids).
These 2 building blocks are known as essential fatty acids. ‘Essential’ in this context implies that they are fatty acids necessary for body regulation, metabolism and the manufacture of cellular membranes, and because they cannot be synthesized by mammals (they lack desaturase enzymes needed for their production), they must be ingested.
Omega-3 and omega-6 are termed short chain polyunsaturated fatty acids, and various long chain polyunsaturated fatty acids can be produced from these e.g. omega-3 (EPA or DHA) and omega-6 (GLA, DGLA or Arachidonic acid).
By contrast, healthy humans have the enzymes to synthesize omega-9 fatty acids and it is for this reason that they are considered non-essential fatty acids.
Omega-3 and Omega-6 Balance
Note: Further information concerning omega-3 and omega-6 can be found in Eicosanoid Inflammatory Mediators (Leukotrienes and Prostaglandins) and Allergies
It has been suggested that the balance of omega-3 to omega-6 is important to maintaining good health. Advocates note that the ‘ideal’ omega-3 to omega-6 ratio (1:1 up to 1:4) becomes skewed heavily in favor of omega-6 in the Western processed diet. This can result in a ratio in excess of 1:10 and in more extreme cases, up to 1:30 i.e. omega-6 intake is 30 times greater than omega-3.
Some research indicates that an imbalance may increase the risk of cardiovascular disease. However, this is disputed by others who feel that whilst omega-3 is very important in preventing heart disease, the role of omega-6 is overstated or not fully understood. Therefore, they consider the ratio/balance to be too simplistic a representation of a much more complex scenario.
Despite a lack of scientific consensus on the topic, it has become increasingly common for the media to label omega-3 fatty acids as “good fats” (prevent heart disease and inflammation) and omega-6 fatty acids as “bad fats” (promote narrowing of the arteries and inflammation). However, given that both types of essential fatty acids are necessary for good health, the question to be determined is what is the optimal amount? Interestingly, the American Heart Association (AHA) recommends that 5-10% of a person’s daily calories should be derived from omega-6 fatty acids (Harris et al. 2009).
Omega-3 Sources
Naturally occurring sources rich in omega-3 include oily fish (in particular cold water fish such as halibut, herring, mackerel, salmon and sardines) as well as seed oil (e.g. kiwifruit, flax, ligonberry, black raspberry) and nut oil (e.g. butternuts, persian walnuts, pecan and hazel nuts). As omega-3 is produced in the chloroplasts of algae and green leaves, it is present to varying degrees, in creatures that feed on them e.g. fish on algae, cattle on grass. It is also available in supplement form as gel capsules, gummy fish forms, oil and tablets.
Recommended Daily Allowance of Omega-3
Even though there is no formal recommended daily allowance (RDA) for fatty acids such as omega-3, the US FDA classifies the following as “generally recognized as safe”:
A maximum of 3 grams fish oil daily of which no more than 2 grams daily should be derived from supplements.
Function and Benefits of Omega-3
Omega-3 appears to have various important functions in the body, in particular:
- Body regulation. Together with omega-6, omega-3 is involved in making hormone-like lipid compounds called prostaglandins. Prostaglandins help control various activities in the body associated with the heart, kidneys and digestive system and regulate blood pressure and clotting as well as inflammation and body temperature. In addition, prostaglandins are involved in making other hormones.
- Helping to prevent heart disease and minimizing risks for those with heart disease. Omega-3 may help achieve this in numerous ways, such as through lowering cholesterol and blood pressure, as well as reducing the blood protein homocysteine, triglyceride levels and the risk of blood clots. It has also been suggested that it can reduce abnormal heart rhythms, the build-up of arterial plaque (known as atherosclerosis, arteriosclerotic vascular disease or ASVD) and lower the risk of suffering heart attacks and strokes.
In addition to its anti-coagulant and anti-inflammatory benefits, omega-3 appears to be involved in development and correct functioning of the brain and eyes e.g. signal transmission. Furthermore, studies have suggested it may have anti-cancer properties and improve stamina and endurance.
Evidence Concerning Omega-3 Benefits
Out of the different forms of omega-3, it is DHA (Docosahexaenoic acid) and EPA (Eicosapentaenoic acid) that have received most attention. A number of studies dating back to Dyerberg et al. 1975 have indicated their importance at preventing cardiovascular disease. In 2004, the US FDA granted “qualified health claim” status for DHA and EPA related specifically to cardiovascular disease.
However, there is not a consensus of scientific opinion concerning the claimed benefits of omega-3 (including DHA and EPA) for other conditions, and as such, these claims should be treated with caution at the present time.
Side Effects of Omega-3
The most commonly observed side effects associated with taking omega-3 fish oil or supplements include:
- Bad breath or fishy breath.
- Fishy aftertaste in mouth.
- Heartburn or indigestion.
- Upset stomach.
- Looser stools or diarrhea.
- Nausea.
Those symptoms more likely when the source of omega-3 is either flaxseed or flaxseed oil include:
- Abdominal discomfort and pain.
- Bloat.
- Constipation if taken with insufficient water.
- Gas and flatulence.
However, as with any medication, more serious side effects are possible that may require medical assistance. Fortunately, they tend to be very rare and include the risk of an allergy reaction; in particular for someone allergic to fish. Symptoms of allergies involving food include rashes or hives, tingling mouth and throat with possible swelling in these regions or elsewhere on the body, and problems swallowing or breathing.
Notable side effects usually occur when the daily dose exceeds 3 grams of fish oil a day. Examples include:
- Increase in low density lipoprotein or LDL (‘bad cholesterol’). This substance transports cholesterol in the body and is associated with an increased risk of heart disease due to promoting the build-up of arterial plaque.
- Bleeding and general ease of bruising. Of particular concern is the risk of gastrointestinal bleeding or bleeding in the brain (hemorrhagic stroke).
- Hyperglycemia (high blood sugar), in particular for people with diabetes.
An additional issue concerning omega-3 is the possible build-up of heavy metals and toxins e.g. mercury, from consuming fish oil supplements. It is important only to buy supplements from a reputable, high quality source. For example, Holland & Barrett state their omega-3 fish oil is, “Laboratory tested to meet strict quality control standards for potency, purity and disintegration” and “molecularly distilled to remove mercury, PCB’s, heavy metals and dioxins.”
Omega-3 and Allergies
The issue of whether omega-3 is beneficial as a natural treatment for allergies divides opinion. Advocates substantiate their claims by referring to:
- A diet lacking in essential fatty acids tends to result in skin problems such as eczema.
- Essential fatty acids have natural anti-inflammatory qualities which may help treat various allergy symptoms such as allergic rhinitis (Hoff et al. 2005)
- Essential fatty acids are involved in the manufacture of prostaglandins and are therefore associated with allergic reactions.
- Essential fatty acids help boost the body’s immune system.
- The German study, Hoff et al. 2005, found that a high content of omega-3 in red blood cell membranes or in the diet, was associated with a decreased risk of allergic sensitization and allergic rhinitis.
However, others less convinced are of the opinion that, aside from circumstantial and anecdotal evidence, research concerning the issue is sparse and even then, one UK study (Anandan et al. 2009) found, “that supplementation with omega 3 and omega 6 oils is probably unlikely to play an important role as a strategy for the primary prevention of sensitization or allergic disease.”
