polyunsaturated fat

A recent review paper examines the biology and clinical effectiveness of polyunsaturated fat in improving outcomes for patients with rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disorder that often affects the joints, but can also affect other major tissues. Our understanding of the mechanisms behind the disease has advanced, in addition to the optimization of novel drugs that have greatly improved conditions for RA patients. There is a subset of patients, however, that still does not respond well to current therapies.

One interesting factor that plays a role in RA is polyunsaturated fatty acids, or PUFAs, which are known to impact the immune system and may consequently affect inflammatory diseases. One type of these fats, n-3 PUFAs, are anti-inflammatory and have been taken as supplements to either reduce the severity of or prevent the onset of RA. A group in Italy reviewed the current literature on the effects of polyunsaturated fat on rheumatoid arthritis, and their report was recently published in the journal Lipids in Health and Disease.

The anti-inflammatory n-3 PUFAs are primarily found in fish oils and plants in our diets, and studies have noted that western diets normally do not contain enough of these fats to be effective. N-3 PUFAs are able to reduce the overactivity of immune cells by limiting their uptake of amino acids, which are important for cells to produce proteins and to function. In animal-based models of inflammation, the uptake of these fatty acids is associated with lower levels of pro-inflammatory cytokines. Multiple studies with animal models involving arthritis also see that supplementation of fish oils can either decrease the incidence or severity of arthritis. In some of these models, the fats were shown to be able to help maintain bone density and increase muscle weight. Overall, based on preclinical studies, n-3 PUFAs could potentially have a positive role in RA.

Accordingly, clinical studies have been performed to determine the effectiveness of n-3 PUFAs on alleviating the symptoms of RA. A host of studies examined the effects of supplementing oils high in n-3 PUFAs into the diet of RA patients and observed some benefit. Some of the benefits included: improvement in morning stiffness, reduced pain, and increased responsiveness to therapies. One study tested administering fish oils intravenously and observed similar effects as oral administration. Furthermore, meta-analyses, which compile data from a multitude of studies, have concluded that n-3 PUFAs can reduce joint pain, morning stiffness, and painkiller consumption in RA patients.

There is accumulating evidence that certain polyunsaturated fat, such as those from fish, have noticeable anti-inflammatory effects that translate to better clinical parameters for patients with RA. Nonetheless, there remain some questions that are unanswered. We do not have data that outlines how n-3 PUFAs can affect newer RA drugs and we lack details on how they can affect the joints on a cellular level. Future clinical trials will more accurately determine the benefits of n-3 PUFAs and whether they are appropriate for all RA patients to alleviate their symptoms.

Written by Branson Chen, BHSc

Reference: Navarini L, Afeltra A, Afflitto GG, Margiotta DP. Polyunsaturated fatty acids: any role in rheumatoid arthritis?. Lipids in Health and Disease. 2017 Oct 10;16(1):197.

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