What is linseed oil actually good for? Maybe your ACL!

Effect of flexase oil on the prognosis of actual anterior cruciate ligament rupture: a randomized, placebo-controlled trial.

Tang H, Xu Z, Lin J, Sun W and Xiw Y. Ben J Transl Res. 2022;14(10):7252-7259.

Full text is freely available

Take home message

People who supplemented their diet with flaxseed oil experienced slightly better results two years after anterior cruciate ligament (ACL) reconstruction than participants in a control group.

Background

Although we often focus on surgery and rehabilitation to optimize outcomes after an ACL injury, we may also want to consider other strategies to improve one’s prognosis. Flaxseed oil, which contains α-linolenic acid (an omega-3 fatty acid), may suppress inflammation and be beneficial. However, the impact of linseed oil supplementation on recovery after ACL reconstruction remains unclear.

Study aim

Tang and colleagues completed a randomized, placebo-controlled trial to investigate the impact of dietary flaxseed oil on outcomes in people undergoing ACL reconstruction.

Methods

The authors randomized 142 participants undergoing ACL reconstruction into two equal groups. The experimental group took six linseed oil capsules (9 grams total, 4.2 grams of α-linolenic acid) per day. The control group took six corn oil capsules (9 grams total, minimum α-linolenic acid) per day. Dietary supplements were continued for two years after ACL reconstruction. The researchers contacted participants by telephone every two weeks to ensure compliance with study guidelines. After the two-year intervention period, participants completed a series of questionnaires to assess patient-reported outcomes: 1) Knee Injury and Osteoarthritis Outcomes Score (KOOS), 2) International Knee Documentation Committee (IKDC) score, 3) the Lysholm Knee Scoring Scale, and 4) Tegner Activity Scale.

Results

After two years, participants who used flaxseed oil had 1) better IKDC scores, 2) better KOOS scores for sport and quality of life, 3) higher rates of return to their previous sport level (56 vs. 39%), and 4) less side effects to the knee (e.g. giving in episodes, pain) than the control group. The groups had no differences in KOOS pain or symptoms, Tegner scores, Lysholm scores, or treatment satisfaction.

Viewpoints

Participants who received flaxseed oil supplements had slightly better results than those in the control group. This preliminary study shows that a diet supplemented with flaxseed oil high in α-linolenic acid can improve outcomes after ACL reconstruction. It will be interesting to see if other high-quality research confirms these results with flaxseed oil or another source of α-linolenic acid. One detail not mentioned that could be important is dietary habits beyond flaxseed oil. For example, some participants in the control group may have consumed a diet rich in α-linolenic acid.

Clinical implications

Despite the need for more research, doctors can discuss the small benefits and few risks associated with flaxseed oil supplementation. It is also important to remind athletes to purchase supplements that have been tested to ensure they are getting what they expect in each capsule.

Questions for discussion

Do you recommend these or other nutritional supplements for patients who have undergone ACL reconstruction? If so, what did you suggest and what sources led you to recommend this supplement?

Written by Kyle Harris
Reviewed by Jeffrey Driban

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