There is good scientific evidence that the omega-3 fatty acids in fish oil can help prevent or slow heart disease. That’s good news for people with psoriasis and psoriatic arthritis, who are at a higher risk of developing heart disease.
But does fish oil help psoriatic symptoms? The evidence for that is less clear, said Dr. Wilson Liao, a dermatologist the University of California, San Francisco.
Liao and his colleagues in 2014 published a review of studies of nutritional supplements used for psoriasis in the Journal of the American Academy of Dermatology (JAAD). Of the four supplements they reviewed, omega-3s produced the most benefits. Not all the studies found fish oil improved psoriatic symptoms, however, and those that did most often involved high doses.
So when does fish oil help psoriasis and psoriatic arthritis? We review the research:
High dose yields best result
The most potent omega-3s in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
Two randomized double-blinded controlled trials (the research gold standard) in the JAAD review found omega-3 supplements improved redness, thickness, and scaling in plaque and guttate psoriasis. These trials, however, delivered intravenous omega-3s at high doses—between 2.1 and 4.2 grams of EPA and 8 and 21 grams of DHA. In contrast, a single concentrated fish oil capsule typically contains between half a gram and a gram (500-1,000 milligrams) of combined EPA and DHA.
Some studies using lower amounts (in one, patients took 10 capsules daily to get 1.8 grams of EPA and 1.2 grams of DHA) also improved skin after three months of use. But several studies show no benefit over placebo capsules. There are few studies of fish oil in psoriatic arthritis, but trials of omega-3s in other types of inflammatory arthritis showed supplementation of about 3.3 grams daily reduced pain and stiffness.
Food or supplements?
Wild-caught and farmed salmon deliver between 500 to 1200 milligrams of combined EPA and DHA per 6-ounce serving, less than levels used in most studies. Some research suggests the body is better able to absorb and use omega-3s from fish versus capsules, however, and fish provides other beneficial nutrients.
Walnuts, flax seed, and other plant sources of omega-3s contain a less-potent type of fatty acid than marine sources, and probably can’t deliver enough omega-3s to affect psoriatic symptoms, said Philip Calder, a professor of nutritional immunology at the University Southampton in the United Kingdom.
What the researchers suggest
Liao doesn’t prescribe omega-3 supplementation to his patients. If they ask, he encourages them to add salmon to their diet.
“If they want to try supplements I advise one gram of EPA and half a gram DHA daily for eight weeks to see if they notice improvements in their skin,” he said.
But check with your doctor before starting omega-3 supplementation, especially at higher doses. High doses can cause nausea, intestinal cramps, diarrhea, and gas, Calder said.
Omega-three supplements can also increase bleeding risks in people who take blood thinners, such as warfarin, he said.
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