Today's North American diet is taking a toll on our skin.
Chronic skin conditions such as psoriasis, inflammation as well as wrinkles and skin laxity associated with aging have been linked with the unhealthy ratios of fats caused by most Americans' meat-and-potato diets. We tend to overeat the proinflammatory fats in beef, butter and vegetable oils and don't consume enough of the complexion-friendly oils found in fish. Rich in omega-3 fatty acids, fish oils have been shown in numerous studies to promote a healthy skin tone and relieve inflammation.
Omega-3 fatty acids are a type of polyunsaturated fatty acid (PUFAs). Omega-3s comprise the essential fatty acid alpha-linolenic acid (ALA) and its non-essential longer chain derivatives eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
Another type of PUFA, omega-6 fatty acids comprise the essential fatty acid linoleic acid (LA) and its non-essential longer chain derivatives gamma-linolenic acid (GLA) and arachidonic acid (AA). Although essential for normal health and well-being, omega-6 fatty acids can lead to inflammation when consumed in high quantities. In particular, arachidonic acid is involved in the early stages of inflammation.
Both the essential omega-3 and omega-6 fatty acids must be obtained through our diets as the human body can't manufacture them. Omega-6 fatty acids are abundant in commonly used cooking oils such as corn, soybean, sunflower and safflower. Omega-3 fatty acids are available in many types of fish as well as unrefined canola oil, walnuts, deep green leafy vegetables, blueberries and ground flaxseeds. (See Table 1.)
Researchers attribute the health benefits of omega-3s to their abilities to maintain cellular processes. They also improve and preserve the integrity and function of the cell membrane. Cell membranes built with EFAs are less rigid and more fluid than those built with saturated fats or proinflammatory omega-6s.
Fluid cells allow the transport of valuable nutrients into the cells. They also help keep toxins out of the cells, elasticize tissue, expand blood vessel walls and improve overall function of organs.
Omega-3 essential fatty acids are metabolized in the body by a series of competing enzymes in alternating desaturation and elongation reactions. ALA, which is the parent fatty acid, is metabolized to longer chain PUFAs. Eventually, certain longer chain PUFAs-namely EPA-are converted into eicosanoids.
Eicosanoids such as prostaglandins, leuokotrienes and thromboxanes influence or regulate many body processes. These processes include inflammation, blood clotting and blood flow, hormones and immune function.
The Inflammation Connection
Consuming too much refined omega-6 fatty acids has been shown in many studies to promote chronic inflammation.
Together with saturated and trans fats, excess omega-6 fatty acids encourage the production of inflammatory prostaglandins-particularly the series-2 type called PGE2-and leukotrienes, primarily LTB4. It is, therefore, reasonable to speculate that these proinflammatory mediators can be manipulated by dietary PUFAs.
Omega-3s, on the other hand, counteract inflammation. Not present in the epidermis, DHA and EPA are both metabolized by skin epidermal 15-lipoxygenase to 15-hydroxyeicosapentaenoic acid (15-HEPE) and 17-hydroxydocosahexaenoic acid (17-HoDHE). These metabolites accumulate in the epidermis after ingesting fish oils, research shows. And this may partly explain the beneficial effects of fish oil on cutaneous inflammation.
EPA from cold-water oily fish, such as salmon, sardines, mackerel and anchovies, can diminish the activity of LTB4, PGE2 and the inflammatory cytokines. This significantly improves clinical inflammatory conditions such as rheumatoid arthritis as well as depression, cardiovascular disease and inflammatory bowel disease.
In clinical trials, fish oil supplementation has demonstrated the ability to alleviate psoriasis lesions with moderate-to-excellent results. Positive results also have been seen in patients with psoriatic arthritis. Patients experienced decreased disease activity and a lowered need for anti-inflammatory drugs.
The skin requires a steady supply of fats to lock in moisture and maintain suppleness and smoothness. The most abundant PUFA in human skin is LA (omega-6). In the epidermis, the metabolism of polyunsaturated fatty acids is highly active. Clinically, patients respond very quickly to internal and topical application of PUFAs.
EFAs help maintain the stability and fluidity of the natural hydrophilic or water loss barrier, which prevents toxic substances from entering or irritating the skin. In addition, EPA produces the chemical messenger prostaglandin E3, which augments blood flow and reduces redness and inflammation.
EFA deficiency manifests in the skin as scaliness, weakened capillaries, itching and increased water loss. Patients experience dry, wrinkle-prone skin. They ultimately can develop skin disorders such as eczema, xerosis, dermatitis and psoriasis.
Not surprisingly, both the omega-6 GLA and the omega-3 EPA in balance have been shown to improve the function of the skin by reducing dryness, pruritis and inflammation. Omega-3s also improve the barrier function of the skin and help reduce trans-epidermal water loss.
Researchers don't yet know the exact nutritional requirements for omega-3 fatty acids. The Technical Committee on Dietary Lipids of the International Life Sciences Institute of North America recently recommended a dietary intake of 250 mg to 500 mg of EPA and DHA to reduce the risk of coronary artery disease. Table 2 reviews the current recommendations for omega-3 supplementation in the normal population and for prevention and treatment of selected health conditions.
Since most Americans don't eat enough fish, supplementation can help patients maintain healthy fatty acid ratios. To date, no studies have compared absorption ratios from food or supplements. However, when people cook fish they tend to destroy the fatty acids from over heating. Supplements, therefore, can achieve higher ratio of the pure fatty acids.
There have been numerous studies, however, addressing the issue of fish oil absorption. They have presented evidence that fish oil in its natural triglyceride form is absorbed substantially better than the ethyl ester form. Cleaving the EPA and DHA from the naturally occurring triglyceride molecule results in a mono and diglyceride. This forms the ethyl ester form of EPA and DHA. The EPA and DHA can then be concentrated into an ethyl ester form.
Examples of natural triglyceride brands include Eskimo-3 Fish Oil by Enzymatic Therapy, Carlson Nutritional Supplements, Nordic Naturals and NutraSea.
Quality and Bioavailability
Fish oil products vary greatly in quality and bioavailability of EPA and DHA. (See Table 3.) Products are considered "natural" if they are not chemically modified and concentrated. They exist in their natural triglyceride form, containing less than 38 percent omega-3 fatty acids.
Fish oil manufacturers should test oils for the absence of heavy metals like mercury, lead, cadmium and arsenic. Several quality parameters can help health care practitioners recommend the safest, cleanest, stable oil to our patients.
Acid value measures free fatty acids in the oil. Higher levels of free fatty acids are associated with a decreased quality of oil. Providers should look for values less than 3 mg KOH/g.
Peroxide value indicates oil quality and freshness. If the oil has been exposed to oxygen, the PV will go up as an indicator of rancidity. PV should be less than 5 meq/kg.
Anisidine value (AV) measures secondary oxidation products in the oil and should be less than 20.
The TOTOX value is the result of the calculation of (2 x PV) + AV. This measure identifies fish oil that has the maximum permissible quantity for both PV and AV. TOTOX should be below 26, otherwise the oil will be unacceptably oxidized. Not all brands measure TOTOX and other quality parameters, so it is important to ask questions of the brand to ensure you are giving the highest quality oil to get maximum results.
Physician's can receive these values through the suppliers of the oils. Hopefully in time, with more questions being asked, the brands will provide this information on the labels, allowing us to have easier access to important quality information.
Numerous health organizations recommend consuming fatty fish such as salmon, mackerel and sardines at least two times per week. However overcooking, availability, taste and a change in lifestyle often prevent individuals from receiving enough omega-3s from their diet.
Fish oil supplements are a convenient and easy way to incorporate more of the skin-friendly omega-3s into the diet. As science continues to validate the efficacy of these nutritional oils, we can look forward to the possibilities of preventing and treating many common conditions with omega-3 fatty acids.
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Karlene Karst, RD, is a nutritional researcher, educator, spokesperson and author of many books including the international best seller, Healthy Fats for Life (Wiley, 2004). Disclosure: Ms. Karst indicates she is a paid consultant and serves as a speaker and advisory board member with Nature's Way and Enzymatic Therapy.