Osteoarthritis is the most common form of arthritis in the knee. The condition damages cartilage, the tissue that acts as a cushion at the ends of bones within joints. This damage causes pain and mobility problems in the joint.

People can control osteoarthritis (OA) symptoms with self-management techniques. Diet plays a huge role in the progression of OA. There are diet tips that can be followed to help keep OA under control.

Maintaining a healthy weight is important. Additional weight leads to more stress on already-damaged joints. People should follow a healthy, well-balanced diet to stay at a healthy weight.

There are a lot of myths about the foods people with OA should eat. While there is no scientific evidence for some of these foods, there are other foods that may be useful in a healthy diet.

Tips for maintaining a healthy weight

Maintaining a healthy weight is key to OA because an increase in weight puts additional strain on the joints. Extra strain makes OA worse, which means more pain, inflammation, and swelling.

A woman inspects ingredients in a supermarket.
People with OA of the knee should pay close attention to the nutritional content of their food.

People with OA of the knee should read nutritional labels carefully. It is important to look out for saturated fats which are deemed unhealthy fats.

Foods that claim to be low-fat or healthy can be high in sodium, and even higher in sugar.

Natural fiber can make people feel fuller for longer as well as help lower cholesterol or prevent diabetes. It is also important to look for important nutrients such as vitamins and healthy fats.

As mentioned earlier, food preparation is important. Fresh fruits and vegetables are always better. Baking, grilling, and steaming are the best options. Deep-frying adds extra calories and takes away much of the nutritional content.

Exercise is considered the most effective non-drug treatment for reducing pain and helping to improve movement in patients with OA. Knee pain may make performing some exercises more difficult but even simple stretching and other motion exercises can have a big impact.

Walking is a great form of exercise. It doesn’t cost any money and has a vast amount of benefits for people with OA of the knee:

Exercise strengthens the muscles which can help to protect joints affected by OA. Even as little as 30 minutes of exercise a day can help with OA symptoms.

Pairing a healthy diet with exercise should ensure the best results. People with OA of the knee should see a doctor before starting any exercise program to talk about what their body can handle. Some people may have to start with small exercises and slowly increase their intensity over time.

Anti-inflammatory diets and osteoarthritis

The National Cancer Institute defines inflammation as “redness, swelling, pain, and/or a feeling of heat in an area of the body.” It is a way in which the body responds to any disease, injury or irritation that it encounters.

Fish oil capsules.
Omega-3 fatty acids can be found in oily fish. These acids can help reduce damage from inflammation.

Inflammation is both a cause and a symptom of OA. As a result, anti-inflammatory foods could be a great addition to a healthy diet for people with OA.

Certain types of fish are rich in omega-3 fatty acids. These acids help reduce levels of two proteins called the C-reactive protein (CRP) and interleukin-6, that cause inflammation. Some people who have OA also have elevated levels of CRP which can lead to increased pain and swelling.

Omega-3s interfere with cells that play a key role in how the body responds to inflammation. The omega-3 fatty acids found in fish can help stop inflammation before it damages the joints.

According to the Arthritis Foundation, people who regularly eat fish high in omega-3s are less likely to develop rheumatoid arthritis.

Eating more healthy omega-3 fats may help to reduce joint swelling, pain, and stiffness caused by OA. These fats can also help prevent other diseases caused by inflammation such as heart disease.

Fish that are rich in omega-3s include salmon, tuna, sardines, and mackerel. Eating a 3 to 6 ounce serving of fish at least four times a week can help reduce OA inflammation and protect the heart.

Some fish with high levels of omega-3 fats are also high in mercury. Mercury can damage the brain and nervous system if eaten in large quantities.

The Arthritis Foundation list the following fish as high in omega-3s but low in mercury:

  • Atlantic mackerel
  • Lake trout
  • Salmon
  • Herring
  • Sardines, canned
  • Anchovy
  • Sablefish or black cod
  • Albacore tuna

Fish-oil supplements are also available, but these do not offer as many benefits as eating the actual fish.

Fruits and vegetables

Fruits and vegetables contain antioxidants that support the immune system and fight inflammation. People should aim to eat at least 1.5 to 2 cups of fruit and 2 to 3 cups of vegetables per day.

Berries are loaded with antioxidants. Strawberries, tart cherries, and red raspberries are just a few of the options believed to have anti-inflammatory properties.

Avocados are high in anti-inflammatory monounsaturated fat. They are also a good source of vitamin E, which has anti-inflammatory effects. Diets high in these compounds have been linked to a decreased risk of joint damage seen in early OA.

Fruits and vegetables
Fruits and vegetables contain many nutrients that help the body fight inflammation that causes OA.

Watermelon and grapes are another option. Watermelon can help reduce CRP levels and is naturally high in carotenoid beta-cryptoxanthin. This compound can help reduce the risk of rheumatoid arthritis.

As watermelon is around 92 percent water, it is useful for hydration and water management.

Fresh red and black grapes contain the potent anti-inflammatory resveratrol.

Energy production and other body processes produce harmful byproducts called free radicals that can damage the cells in your body. Free radicals have been linked to inflammation that attacks the joints.

Green leafy vegetables such as broccoli and spinach are packed full of healthy antioxidants such as vitamin A, C, and K, which help to protect cells from free radical damage. These foods also contain high levels of calcium.

Broccoli and other cruciferous vegetables such as cabbage and Brussels sprouts also contain the natural compound sulforaphane.

In one animal study, sulforaphane and another compound called glucosinolate blocked the inflammatory process and slowed down the cartilage damage in OA. Glucosinolate is found in pungent plants like horseradish, mustard, and cabbage.

Peppers are a great source of vitamin C, which preserves bone and can play a role in protecting cartilage cells.

Olives and extra virgin olive oil contain oleocanthal. This compound is a natural anti-inflammatory agent that has properties similar to the drug ibuprofen.

A group of vegetables known as nightshade vegetables which includes tomatoes, potatoes, and peppers contains the chemical solanine. Some people believe this chemical can cause arthritis pain. However, no studies or research have ever shown this claim to be true.

Some people may have sensitivities to certain foods, regardless of the solanine content, which may aggravate symptoms. Removing potential allergic or sensitive foods through an elimination diet may be a way to improve symptoms.

Food preparation

Preparing vegetables in the right way before eating is also important.

  • Steaming is the preferred method of cooking because the process preserves the important nutrients in the vegetables
  • Vitamins and antioxidants may leach out in the water if too much is used during food preparation
  • Avoiding overcooking food ensures that it holds in the vitamins and minerals
  • Deep fryers and similar methods add a lot of extra fat and calories

Foods to avoid with osteoarthritis

People with OA of the knee should try to avoid some foods to not aggravate the condition further.

Avoiding sugar not only helps people cut calories and maintain a healthier weight, but sugar can trigger the release of cells which can increase inflammation. Processed forms of sugar are the best forms to avoid for this purpose.

Salt can cause cells to attract water, which could aggravate OA. One of the most common symptoms of OA is joint swelling, and an overdose of salt can worsen the condition.

Processed food and fast food are high in salt intake and should be limited. The American Heart Association states that many Americans consume around 3,400 milligrams of sodium a day. This amount is more than twice the 1,500 milligrams that they recommend people should consume.

About 75 percent of the sodium people consume comes from sodium added to processed foods and restaurant foods. Many people may not realize just how much sodium they are consuming.

Approximate amounts of sodium in a given amount of table salt according to the American Heart Association are below.

  • 1/4 teaspoon salt = 575 milligrams of sodium
  • 1/2 teaspoon salt = 1,150 milligrams of sodium
  • 3/4 teaspoon salt = 1,725 milligrams of sodium
  • 1 teaspoon salt = 2,300 milligrams of sodium