Nightshade foods: This food group includes tomatoes, potatoes, eggplant and capsicum. There is no proof that these foods have any effect on arthritis symptoms. Acid-producing foods: Arthritis is not caused by eating ‘acidic foods’ like oranges, lemons or tomatoes. Very few foods are as acidic as our digestive juices. Foods termed ‘acidic’ are usually very rich in vitamin C, which is beneficial to the immune system. So avoiding these may do more harm than good. Dairy products: There is no proof that dairy products cause arthritis. Dairy products are a rich source of calcium, which is an important building block for strong bones. Many people with arthritis are at an increased risk of osteoporosis (thinning of the bones) so dairy products may be extra important to maintain bone health. Meat and meat products: There is mixed evidence about the effects of vegetarian diets on arthritis. These diets tend to increase your intake of vitamins as you eat more vegetables and fruits. Lower levels of fat in this diet may also help you to lose weight. These factors may help with arthritis symptoms. However, a strict vegetarian diet may mean you miss out on other important nutrients, such as iron and vitamin B12.