Omega-3 and omega-6 are polyunsaturated fatty acids that are termed “essential” nutrients. Like vitamins, the body cannot manufacture them and must get them through food or supplements.
There are three major categories of omega-3 fatty acids: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is found in high concentrations in certain plant oils such as flaxseed and hemp. Once eaten, the body converts ALA into EPA and DHA – the two forms it uses most extensively. EPA and DHA in their pure form are found in fatty fish (sardines, anchovy, mackerel, herring, and salmon) and other marine organisms. In addition, other types of omega-3 fatty acids that work together with EPA and DHA to deliver an astounding array of health benefits.
Every cell in the human body has a fat (lipid) component made up of essential fatty acids (EFAs). The reason these fatty acids are so important revolves around their role in cellular membranes. A diet that is deficient in omega-3 fatty acids, particularly EPA and DHA, results in altered cell membranes. Without a healthy membrane, cells lose their ability to hold water, vital nutrients, and electrolytes. They also lose their ability to communicate with other cells and be controlled by regulating hormones. They simply do not function properly. Cell membrane dysfunction is a critical factor in the development of virtually every chronic disease, especially cancer, diabetes, arthritis, and heart disease. Not surprisingly, omega-3 fatty acids have shown tremendous protective effects against all of these diseases.
Essential fatty acids support the cardiovascular, reproductive, immune, skeletal, renal, and nervous systems - and improve the health of the skin. They also produce derivatives that regulate functions such as heart rate, blood pressure, blood clotting, fertility, and conception.
Chronic deficiency of the fatty acid omega-3 has been linked to heart attacks, cancer, Alzheimer’s disease, schizophrenia, insulin resistance, asthma, postpartum depression, stroke, obesity, diabetes, arthritis, ADHD, and accelerated aging, among other conditions. Inflammation, found to be a key component in many chronic diseases, has been strongly linked to omega-3 deficiencies.
Omega-3s are highly concentrated in the brain and appear to be particularly important for cognitive and behavioral function. Many recent studies have linked low levels of EPA and DHA in the brain to seasonal mood changes, depression, schizophrenia, memory loss, and a higher risk of developing Alzheimer's disease. (1,2)
Research has found that people who experience depression have relatively low levels of omega-3 fatty acids in their blood, and that the balance of omega-3 fatty acids in their brain becomes skewed. Studies show that fish oil supplements rich in EPA and DHA help to alleviate symptoms associated with brain disorders such as schizophrenia, bipolar disorder, and manic depression.(3)
Research has shown that omega-3 deficiency promotes high blood levels of estradiol, a marker for high susceptibility to breast cancer.(4,5,6) In one study, researchers evaluated over 250 patients with breast cancer, analyzing their fat relative to 90 women without breast cancer. Their conclusion was that there was a protective effect from omega-3 fatty acids that affected breast cancer risk.(7)
PMS is also associated with elevated estrogen (estradiol) levels. High estrogen levels in the blood tend to increase insulin levels and this reduces blood sugar.(8,9,10,11) Low blood sugar leads to irritability, which is a symptom of PMS.
Infants who do not get enough omega-3 fatty acids from their mothers during pregnancy are at risk for developing vision and nerve problems. Researchers are linking inadequate intake of omega-3s in pregnant women to premature birth and low birth weight, and to hyperactivity and ADD in children. Essential fatty acids are particularly critical for nerve development and maturation of sensory systems in children, with males having higher needs than females.
Too much omega-6 – Not enough omega-3
Despite the critical importance of omega-3s in human health, the vast majority of the North American population has become omega-3 deficient. The average North American diet supplies less than 15% of omega-3 requirements, and even the American Heart Association now recommends a focus on omega-3 intake for healthy individuals (Jan 2003).
How did this widespread deficiency of omega-3 fatty acids come about? While research has shown that both omega-3 and omega-6 are vitally important for good health, the typical North American diet has a huge excess of omega-6s, but nowhere near enough omega-3s.
It is estimated that our species has lived on a balanced EFA diet for the past 400,000 years – one rich in natural omega-3 food sources such as free-range game, wild fish, marine mammals, and nuts. It has only been within the last 100 years that our dietary fatty acid composition has changed for the worse. In the early 20th century food manufacturers began pouring vegetable oils – a source of omega-6 fatty acids – into the food chain. Along with a decline in wild fish and game consumption, and a sharp increase in the use of grains as livestock feed, events conspired to drastically alter the balance between omega-6s and omega-3s in the Western diet.
Many studies now show the extent of the omega-3 deficiency, and the wide range of health problems that have mushroomed as a result.(12,13) While the ideal ratio of omega-6s to omega-3s in the human body is near 2:1, the typical modern diet has resulted in a ratio that is commonly between 10:1 and 25:1. In cases of extreme health problems it can be even higher.
Many popular polyunsaturated vegetable oils – such as corn, safflower, sunflower, and soybean – are high in omega-6 fatty acids but completely lacking in omega-3s. These vegetable oils are present in a variety of baked and processed foods.
In addition, essential fatty acid profiles in food animals such as pigs, chickens, and cattle, as well as associated food products such as eggs and milk, have been altered as a result of modern feedlot practices. Animals once raised in a free-ranging environment with a diet balanced in grasses and grains, are now raised almost exclusively on corn. This diet has created a food supply that is very low in omega-3s and very high in omega-6s. In contrast, cultures who still consume range fed animals, and peoples such as the Inuit and Japanese who regularly consume fish, have superior omega-6/omega-3 profiles and are known for their very low rates of heart disease.(13)
Research as far back as 1968 recognized that range fed animals contained higher amounts of omega-3 fatty acids. The wild pig has 35% EFAs in an omega-6/omega-3 ratio of 1:1, compared to corn fed commercial animals whose ratio is around 20:1. Range fed African cattle contain 16% EFAs, while commercial beef in the US contains almost non-detectable amounts. Range fed chicken egg yolks have an omega-6/omega-3 ratio near 1:1, while commercially fed chicken eggs have been tested as high as 19:1.(14)
What is the Solution?
The typical Western diet contains only about 10-15% of the omega-3 that the body needs on a daily basis. The epidemic of disease resulting from omega-3 deficiency and omega-6/omega-3 imbalance would be quickly remedied if people simply included a sufficient quantity of omega-3 in their daily diet.
For most people, this dietary change would include consuming an omega-3 supplement. However, most people who currently supplement with omega-3 are taking too little. Health Canada has recommended a daily omega-3 intake of 1,100 mg for women and 1,500 mg for men, while the US Department of Health and the National Institute of Health have agreed on an optimum daily intake of between 1,000 – 3,000 mg per day. The US Food and Drug Administration (FDA) has ruled that up to 3,000 mg per day of omega-3 derived from fish oil meets GRAS Generally Recognized as Safe) criteria.
(Note: Be aware that the amount of omega-3 in a supplement capsule is not equal to the total milligram size on the label. This refers to the amount of fish oil in the capsule. The amount of omega-3 can be as little as 30% of that total.)
Flax and hemp oil, while rich in the omega-3 ALA, may not be the best supplement alternatives. Studies have shown that foods rich in ALA are inefficient at increasing cellular levels of EPA and DHA. People who consume a high level of saturated fats (from red meat, for example) or who have certain health conditions, have difficulty converting ALA into usable omega-3 forms. Even in healthy people, as little as 2% of the ALA may be converted into EPA and DHA.(15,16)
By far the best source for omega-3s are certain species of wild fatty fish – sardines, anchovy, mackerel, herring, and salmon – and fish oils derived from them (farm-raised fish often contain much lower levels of omega-3s). Supplements from these fish oils have varying omega-3 concentrations ranging from 30% up to about 70%. Cod liver oil contains only about 20-25% omega-3 and is primarily consumed for its high content of vitamins A and D.
The omega-3 fatty acids contained in fish are considered to be 5-10 times more powerful in their biological activity than those found in plants. In addition, the omega-3s in fish are high in DHA and EPA. Not only are these two omega-3s crucial for brain development and for preventing heart disease, cancer, and many other conditions, but they are superior to ALA when dealing with diabetes, prostate cancer, macular degeneration, and asthma.
- Clandinin M.T. et al. Intrauterine fatty acid accretion rates in human brain: implications for fatty acid requirements. Early Human Dev; 4/2:121-9, 1980.
- Kyle D.J. et al. Low serum docosahexaenoic acid is a significant risk factor for Alzheimer’s dementia. Lipids; 34 Suppl:S245, 1999.
- Peet, M. et al. A dose-ranging study of the effects of ethyl-eicosapentaenoate in patients with ongoing depression despite apparently adequate treatment with standard drugs. Archives of General Psychiatry;59:913-919, 2002.
- Holm, L.E. Treatment failure and dietary habits in women with breast cancer. Journal of the National Cancer Institute 85(1): 32-36, 1993.
- Howe, G.E. Dietary factors and risk of breast cancer: combined analysis of 12 case-control studies. Journal of the National Cancer Institute 82(7): 561-569, 1990.
- Kushi, L.H. Dietary Fat and postmenopausal breast cancer. Journal of the National Cancer Institute 84(14): 1092-99, 1992.
- Maillard V. et al, N-3 and N-6 fatty acids in breast adipose tissue and relative risk of breast cancer in a case-control study in Tours, France. Int J Cancer; 1;98(1):78-83, March 2002.
- Lee, H.P. Dietary effects on breast-cancer risk in Singapore. Lancet 337: 1197-1200, 1991.
- Lee, J.R. Is Natural Progesterone the Missing Link in Osteoporosis Prevention and Treatment. Medical Hypotheses 35, 316-318, 1991.
- Peat, R.F. Progesterone: Essential to Your Well-Being. Let's Live, April 1982.
- Reinish, J.M., The Female Patient, p.87, April 1978.
- Haban et al. The effect of n-3 fatty acid administration on selected indicators of cardiovascular disease risk in patients with type 2 diabetes mellitus. Bratislavske Lekarske Listy 99(1): 37-42, 1998.
- Bibus, DM, Stitt, PA, Holman, RT. Ratios of Linoleic and Alpha Linolenic Acids in the Diet: Implications in the Health of Humans and Companion Animals. Proc. Of the 57th Flax Institute of the USA, March, 1998, North Dakota State Univ., Fargo, ND pp. 49-58, 1998.
- Simopoulos, A.P., Salem N., Am J Clin Nutr, 55:411-4, 1992.
- Pawlowsky, R.J. et al. Physiological compartmental analysis of linolenic acid metabolism in humans. J Lipid Res; 42: 1257-1265, 2001.
- Gerster, H. Can adults adequately convert alpha-linolenic acid (18:n-3) to eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3)? Int J Vitam Nutr Res;68(3): 159-73, 1998.