What is Osteoarthritis?

Osteoarthritis (OA) is the most common form of arthritis in Australia and most often affects the knees, hips and hands. It occurs when the cartilage covering the ends of the bones gradually breaks down and the joint becomes inflamed. Furthermore, this results in pain, stiffness and reduced movement.

Nutrition can support the management of OA in two key ways:

1. By reducing the load on the joints through weight management
2. By reducing inflammation through diet quality.

How Does Weight Affect Osteoarthritis?

Weight management is one of the most effective nutrition strategies for knee and hip OA.
Research shows that each 1 kg of weight lost reduces the load on the knee by approximately 4 kg with every step. In addition, excess body fat also releases inflammatory compounds into the bloodstream, which helps explain why higher body weight is associated with OA in non-weight-bearing joints such as the hands.
A modest reduction of around 5% of body weight may improve physical function in people with knee OA. The greatest improvements in pain are seen with weight loss of around 10%.
During weight loss, adequate protein intake is important to maintain muscle mass, particularly in older adults, as the muscles surrounding the knee and hip help support the joint. Including a source of protein at each meal and spreading intake evenly across the day, helps preserve muscle mass.
This is also relevant for people using GLP-1 medications such as Ozempic, Wegovy or Mounjaro. These medications significantly reduce appetite, which can make it more difficult to meet protein and overall nutritional requirements.

Nutrition to Reduce Inflammation

No single food reduces inflammation on its own. The overall dietary pattern is what matters most. A Mediterranean-style diet, based on vegetables, legumes, wholegrains, fish, nuts and olive oil, is well supported by research and provides a strong foundation.

Omega-3 fats

Omega-3 fats have anti-inflammatory properties. The richest sources are oily fish such as salmon, sardines, mackerel and trout. The recommendation is to consume at least two serves of fish per week, with at least one of these being oily fish.
For those who do not eat fish, plant-based sources of omega-3 include walnuts, chia seeds, linseeds and hemp seeds. Including 30 g of walnuts or one tablespoon of seeds daily is recommended. However, plant-based omega-3  converts less efficiently in the body than the omega-3 found in fish, so an algae-based supplement may be appropriate.

Types of fat and cholesterol

Diets high in saturated fat can increase inflammation, blood cholesterol and are poor for cardiovascular health. Saturated fat is found mainly in processed meats, fatty cuts of meat, butter and baked goods such as pastries and biscuits. Replace these with unsaturated fats, such as extra virgin olive oil, avocado, nuts and seeds, to help reduce blood cholesterol. Increasing fibre intake, particularly from oats, barley and legumes, also helps lower cholesterol.

Antioxidants

Antioxidants help protect the body from oxidative stress, a type of cell damage that may contribute to the development and progression of OA. They are found in a wide range of plant foods, including:
 Fruits and vegetables
 Beans, lentils and other legumes
 Nuts and seeds
 Wholegrains such as oats, barley and psyllium
 Ginger and other herbs and spices, such as turmeric, garlic, cinnamon and rosemary

Ginger contains natural compounds with anti-inflammatory properties. Some studies have found that ginger extract may modestly reduce pain in people with OA. Including fresh or ground ginger in cooking, such as in stir-fries, curries, soups and teas, is an easy way to add it to your diet.
Include a wide variety of colours in your diet, with a practical goal of three different coloured vegetables at main meals. Fresh and frozen produce are equally nutritious options.

Fibre

Fibre is not commonly associated with joint health. However, research has found that higher fibre intakes are linked to a lower risk of developing symptomatic knee OA. Fibre supports the beneficial bacteria in the gut, which play a role in regulating inflammation. It also promotes fullness, which assists with weight management. The recommended intake is 25 g per day for women and 30 g per day for men, and most Australians do not meet these targets.

Are Supplements Effective?

Joint health supplements are widely marketed, and the evidence supporting them varies considerably.
 Glucosamine and chondroitin are among the most common, however high-quality studies have not shown them to be more effective than a placebo. Australian clinical guidelines do not recommend their use.
 Turmeric (curcumin) shows some promising results. An Australian study found it reduced knee pain over 12 weeks, although the effect was modest. The doses used in research are considerably higher than those obtained through cooking. Curcumin can interact with blood-thinning medications, so it is important to consult a GP before use.
 Fish oil may be beneficial, but higher doses are not necessarily more effective.

 Vitamin D is important for bone health, however supplementation has not been shown to reduce knee pain in people with OA.
 Other supplements such as collagen, green-lipped mussel and boswellia are also marketed for joint health. The current evidence for these is limited, and more research is needed before they can be recommended.

Example Day of Eating

Breakfast

Rolled oats cooked with reduced-fat milk or calcium-fortified soy milk, topped with 1 tablespoon of chia seeds and 1/2 cup of mixed berries.

Morning tea

A tub of Greek yoghurt with a piece of fresh fruit.

Lunch

Lentil and roasted sweet potato salad with baby spinach, cherry tomatoes and red capsicum, topped with 30 g of almonds and an olive oil dressing.
Or: Two poached omega-3 enriched eggs with avocado and sautéed spinach on soy and linseed bread.

Afternoon tea

30 g of mixed unsalted nuts and seeds & fruit

Dinner

Grilled salmon with wild rice and roasted vegetables such as broccoli, carrot and zucchini, served with an olive oil and yoghurt dressing.
Or (plant-based): Tofu and vegetable stir-fry with brown rice, sprinkled with sesame seeds.

This day includes a source of protein at each meal, oily fish or a plant-based omega-3 source, several different coloured vegetables and plenty of fibre from wholegrains, legumes, nuts and seeds.

Key Tips

 Follow a healthy portion guide to support weight management
 Include a source of protein at each meal to help maintain muscle mass
 Consume one to two serves of oily fish per week, or include plant-based sources of omega-3 such as walnuts, chia seeds and linseeds
 Consider an omega-3 supplement if oily fish is not regularly eaten
 Limit processed meats such as sausages, bacon, ham and deli meats
 Trim visible fat from meat and choose extra virgin olive oil as the main cooking oil
 Aim for three different coloured vegetables at main meals, using fresh or frozen produce
 Include wholegrains such as oats, barley and brown rice, along with legumes, to meet daily fibre targets
 Take dietary action to reduce blood cholesterol by limiting saturated fat and increasing fibre
 Speak with a GP or dietitian before starting any supplement

Summary:

While nutrition cannot cure osteoarthritis, it can have a meaningful impact on symptoms. Achieving a healthy weight through a combination of good nutrition and regular exercise is the most effective strategy to reduce joint pain. In addition, a diet rich in oily fish, plant foods and fibre and lower in saturated fat can help reduce inflammation.
For personalised advice on managing osteoarthritis through nutrition, feel free to book a consultation.

Disclaimer: The content of this blog is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Please consult with your Dietitian or GP for individualised advice.

References

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