Eating more fibre may reduce the pain and symptoms of osteoarthritis

Including more dietary fibre can reduce pain and symptoms in people with osteoarthritis in their knees

Osteoarthritis is a common condition that makes a person’s joints stiff and painful. It is caused by thinning of the cartilage within the joints, which allows the bones to rub against each. Joint swelling and pain are frequent symptoms. It is the most common of all the different types of arthritis, and typically becomes more common
as people get older.
Dietary fibres are carbohydrates in plant-based foods such as cereal grains, nuts, fruit and vegetables. Fibre cannot be digested, but instead some is fermented in the gut and some fiber passes through the GI tract relative intact. Eating fibre has been shown to lower the risk of getting many diseases, including heart diseases and diabetes. It can also help people to lose weight. It is thought that this is because it helps to trap sugars and fats, and makes you feel full so that you don’t overeat.

What did the authors hope to find? 
The authors wanted to see whether eating foods with lots of fibre would stop people developing knee pain and osteoarthritis in their knees.

Who was studied?
The study looked at nearly 5000 people who were taking part in the Osteoarthritis Initiative or the Framingham Offspring Study. Everyone was aged between 45 and 79. Both studies took place in the United States.

How was the study conducted?
The authors collected information using a questionnaire that asked about people’s food intake. Information about people’s knee symptoms and X-rays were collected every year for 4 years in the Osteoarthritis Initiative and once after 9 years in the Framingham Offspring study.

What were the main findings of the review?
The people eating the most fibre had over 20 grams a day, compared to people eating the least, who had less than 15 grams. The authors found that people who ate more dietary fibre were less likely to develop the symptoms of painful osteoarthritis in their knees. In the Osteoarthritis Initiative the difference was 30%, and 61% in the Framingham study. They also found that people with a high fibre intake were less likely to have worsening knee pain. However, they did not find a link between fibre and damage seen in X-rays. The authors think it is possible that eating more fibre helps people to lose weight and reduce inflammation, which can help to prevent

Are these findings new?
This is the first time that a study has shown that eating more fibre can lower a person’s chance of developing worsening knee pain or osteoarthritis in their knees. There is a strong link between obesity, inflammation and osteoarthritis in the knees. Previously, fibre intake has been shown to reduce body weight and inflammation and
to lower the risk of getting cardiovascular diseases or diabetes.

What are the limitations of the study?
This was not a randomised controlled study, where people are assigned by chance to different groups. Using chance in this way means that the groups will be similar and will allow the variable under investigation to be compared objectively. Randomised controlled trials also have very strict rules about what people can and cannot do during the study. Because of this, the authors cannot prove that the results are due to fibre intake

What do the authors plan on doing with this information?
The authors are planning a randomised controlled trial to test the effect of fibre intake on knee pain.

What does this mean for me?
If you have knee pain, or have a parent with knee pain or osteoarthritis in their knees, you may be able to protect yourself against developing worse pain or osteoarthritis by eating a diet rich in fibre. If you already have osteoarthritis in your knees, it is not too late to choose a high-fibre diet, because this might help you to lose weight and reduce inflammation, which can take the pressure off your joints and reduce your symptoms. The recommended daily intake of fibre is 22.4 grams for women and 28 grams for men aged 51 years and above according to the Dietary Guidelines for Americans 2015–2020. Foods that are good sources of fibre are also healthy choices. This includes whole grains, nuts, fruits and vegetables. Eating a diet rich in fibre may also protect you from other diseases such as heart diseases or diabetes.

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Date prepared: August 2017

Summary based on research article published on: 23 May 2017

From: Dai, Z. et al. Dietary intake of fibre and risk of knee osteoarthritis in two US prospective cohorts. Ann Rheum Dis 2017;76:1411–1419. doi:10.1136/annrheumdis-2016-210810

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