Rheumatoid arthritis can affect adults at any age, but most commonly starts between the ages of 40 and 50. About three times as many women as men are affected. Rheumatoid arthritis is an autoimmune disease. This means that your immune system starts attacking your body’s own tissues instead of germs and viruses, which causes inflammation. Inflammation normally dies down fairly quickly but in rheumatoid arthritis it becomes a long-term (chronic) process. We don’t yet know exactly what sets off the inflammation in rheumatoid arthritis. There’s some evidence that lifestyle factors may affect your risk of developing the condition. Rheumatoid arthritis is more common in people who:
-- smoke
-- eat a lot of red meat
-- drink a lot of coffee.

Rheumatoid arthritis is less common in people who:
-- have a high vitamin C intake
-- drink alcohol in moderation.

The genes you inherit from your parents may increase your chances of developing rheumatoid arthritis, but genetic factors alone do not cause it. Even if you have an identical twin, who shares all the same genetic material as you, and they have rheumatoid arthritis, you only have a 1 in 5 chance of developing it too. And if some of your family have it, the severity can be very different from person to person.