Omega-3 Fatty Acids
(See new study about Omega-3 & Diabetes here)
The omega-3 fatty acids include alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). These are long-chain, polyunsaturated fatty acids. Omega-3 fatty acids have been established as essential for optimum tissue formation. Intense research is studying the optimum amounts of omega-3 fatty acids in the diet and their role in the central nervous system.
ALA is found in plant products; EPA and DHA are obtained from fish oils. Additionally, ALA is converted in the human body to EPA and DHA. ALA is found in unhydrogenated oils, such as rapeseed (canola), flaxseed, and soybean oil, and in margarines and other fats containing such oils. Note that many commercial margarines contain high amounts of trans-fatty acids, which probably outweigh the beneficial effects of the omega-3 oils they contain. EPA and DHA can be introduced into the body directly from cold-water fish such as salmon, mackerel, halibut, and herring.
The beneficial effects of the omega-3 series oils include: lowering cholesterol and triglyceride levels, reducing the risk of heart disease, lowering blood pressure, improving rheumatoid arthritis, and protecting myelin formation and function. There is evidence to suggest that omega-3 oils can be helpful in treating asthma, glaucoma, multiple sclerosis, and diabetes, and in preventing cancer.
Recent research indicates that ALA may have a beneficial effect on coronary heart disease, including the inhibition of atherosclerosis. In one small study of 15 obese persons on daily intakes of 20 g of ALA from margarine products based on flaxseed oil, there was improvement in arterial compliance and thus decreased cardiovascular risk, despite a rise in LDL oxidizability. At the same time, insulin sensitivity and HDL cholesterol diminished.
Another study found that the omega-3 fatty acids, whether ALA supplements from vegetable oil or EPA and DHA supplements from marine sources, have largely parallel effects on hemostatic factors.
Other research has indicated that ALA acts equivalently to n-6 fatty acids with respect to lipid and lipoprotein effects, but that very large amounts of ALA, which is plant-based, is needed to have the effect of reducing tricylglycerol concentrations, which is the hallmark effect of the marine-based omega-3 fatty acids. The study concludes that in terms of effects on lipoprotein metabolism, the plant-derived ALA is not equivalent to the marine-based acids. One area of general agreement is that the interrelationship among the fatty acids and the ratio of ALA to linoleic acid in the diet is an important area for further study.
The omega-3 fatty acids have anti-inflammatory and immunoregulatory effects. Successful treatment of migraines and alleviation of depression with omega-3 fatty acids have been reported. A recent study demonstrated that omega-3 fatty acids improved the short-term course of illness in patients with bipolar disorder. One study showed that patients with panic attacks or a history of agoraphobia may benefit from ALA supplementation.
ALA: flax seeds, flaxseed oil, linseed oil, rapeseed oil, canola oil, soybean oil, pumpkin, and walnuts
EPA and DHA: fish oils, particularly from cold-water fish such as salmon, mackerel, halibut, and herring
The parent fatty acid in the omega-3 series, alpha-linolenic acid (ALA), is converted to eicosapentaenoic acid (EPA), then to docosahexaenoic acid (DHA), then to the prostaglandin E3 series (PGE3). Marine products can introduce EPA and DHA directly into the body.
The essential fatty acids are vitamin F, yet the Food and Drug Administration prohibits the term "vitamin F" for advertising purposes, because of problems with foods such as french fries being advertised as "vitamin enriched" because they were fried in oil.
There are essentially two types of commercial preparations:
- Cooking oils (canola, soybean, and margarines made from these oils; hydrogenated products are not preferred)
- Medicinal oil (flaxseed)
Several manufacturing methods can destroy the nutrient value of the products. Some preferred methods use proprietary names for their process, generically known as modified atmospheric packing methods. Bio-Electron Process, Spectra-Vac, and Omegaflo are some examples. Generally, a high-quality oil will be certified as organic by a reputable third party, will be found in light-resistant containers, may be refrigerated, and will be dated. These oils have been extracted by expeller presses at relatively low temperatures.
The primary uses of omega-3 oils include the following.
- Cardiovascular disease: reducing cholesterol levels and lowering blood pressure
- Allergic and inflammatory conditions, including psoriasis and eczema
- Autoimmune diseases, including multiple sclerosis, lupus, and cancer
Health conditions that may reflect deficiencies in, or which can be improved by supplementation of, omega-3 oils include: acne, AIDS, allergies, Alzheimer's, angina, arthritis, atherosclerosis, autoimmune diseases, behavioral disorders, breast cysts, breast pain, breast tenderness, cancer, cartilage destruction, coronary bypass, cystic fibrosis, dementia, diabetes, E. coli infection, eczema, heart disease, hyperactivity, hypertension, hypoxia, ichthyosis, immune disorders, infant nutrition, inflammatory conditions, intestinal disorders, kidney function, learning, leprosy, leukemia, lupus, mastalgia, menopause, mental illness, metastasis, multiple sclerosis, myopathy neurological diseases, obesity, osteoarthritis, postviral fatigue, pregnancy malnutrition, psoriasis, Refsum's syndrome, Reye's syndrome, rheumatoid arthritis, schizophrenia, sepsis, Sjogren-Larsson syndrome, stroke, vascular disease, vision.
Dosage Ranges and Duration of Administration
- There is no Recommended Dietary Allowance (RDA), yet one or two tablespoons of flaxseed oil daily (or equivalent capsule) is considered optimal for a healthy individual. Capsule doses are 3,000 mg per day for prevention and 6,000 mg per day for treatment.
- A diet that gets 1% to 2% of its calories from linoleic acid has been shown to give maximum tissue levels of DHA, avoiding any apparent deficiency symptoms.
- For rheumatoid arthritis, the estimated therapeutic dose of ALA is 5 g/day, while the estimated therapeutic dose of EPA is 1.8 g/day.
- For agoraphobia: 2 to 6 tablespoons of flaxseed oil daily, in divided doses.
- A healthy person eating a typical diet should reduce consumption of saturated fats and increase consumption of the polyunsaturated essential fatty acids.
Excessive amounts of omega-3 oils may reduce blood-clotting time.Warnings/Contraindications/Precautions
Total fat intake should be considered. The ratio of omega-3 fatty acids to other essential fatty acids may be important in treating some conditions, and the balance of omega-3 to omega-6 oils is essential to the metabolism of prostaglandins. Omega-3 oils should be used with caution in patients who bruise easily, have bleeding disorders, or are on blood-thinning medication.
The omega-3 fatty acids interact with other fatty acids. The optimal ratio of omega-3 to omega-6 fatty acids is 1:4.
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FISH OIL REDUCES TRIGLYCERIDES WITHOUT AFFECTING GLYCEMIC CONTROL
The results of a recent meta-analysis may quell concerns that fish oil unfavorably affects glycemic control in type II diabetics. The review, published in Diabetes Care, included data from 18 randomized, placebo-controlled trials; the studies lasted an average of 12 weeks, included a total of 823 patients, and employed dosages of 3 to 18 g/day of fish oil. Reviewers found that fish oil supplementation did not lead to a clinically significant increase in fasting glucose or glycosylated hemoglobin. A significant triglyceride-lowering effect was noted, particularly in hypertriglyceridemic patients. There was also a significant increase in LDL cholesterol levels, especially among hypertriglyceridemic patients and in those receiving the highest doses of fish oil.
Source: Montori VM, Farmer A, Wollan PC, Dinneen SF. Fish oil supplementation in type 2 diabetes. Diabetes Care. 2000;23(9):1407-1415.