Autoimmune diseases are conditions in which your immune system is overactive and responds harshly to tissues and substances in your body. The diseases affect over 23.5 million Americans, according to the National Women's Health Center. Common forms include thyroid disease, type 1 diabetes, inflammatory bowel diseases, such as Crohn's disease and colitis, the skin condition psoriasis and rheumatoid arthritis. In addition to medical treatments, a healthy diet, limited in particular foods, may improve your symptoms.

Red Meat

Red meat, though rich in protein and nutrients such as iron, may pose problems if you have an autoimmune disease. Autoimmune diseases can cause mild to severe complications in your immune system's capabilities and increase your risk for symptoms ranging from fever and joint pain to extreme fatigue and unintentional weight loss. Eliminating red meat from your diet may help minimize these effects, according to the Cleveland Clinic. Red meat is often high in saturated fat, which may increase inflammation in your body and dampen your heart-health. Red meats particularly rich in saturated fat include organ meats, lamb, spare ribs, porterhouse and sirloin steak and processed meats.

Butter and Margarine

Butter and margarine are additional sources of saturated fat. Margarine also contains trans fats -- fats produced through a process in which hydrogen is added to vegetable oil. Trans fats may pose more cardiovascular damage than saturated fat, since they increase your LDL, or "bad," cholesterol and reduce our HDL, or "good" cholesterol. To protect your immune system the Cleveland Clinic recommends avoiding butter and margarine and opting instead for unsaturated fat forms, such as olive oil.

Refined Carbohydrates

Refined carbohydrate sources, such as enriched flour and sugar, add calories but few nutritional benefits to foods. Unlike whole grains and starchy vegetables, enriched breads, pasta, cereals and snack foods provide little fiber and may have a damaging impact on your blood sugar levels. If you're prone to constipation, due to hypothyroidism or Celiac disease, low-fiber foods may worsen your symptoms. Many refined carbohydrate sources contain gluten -- a storage protein that triggers symptoms of Celiac disease.

Suspected Allergens

Food allergies may coexist with autoimmune diseases. For example, a significant link stands between autoimmune thyroid diseases and celiac disease. Eliminating suspected food allergens, such as wheat, gluten, corn, soy, food additives and dairy products, may help reduce symptoms of diseases such as hyperthyroidism, according to the University of Maryland Medical Center. Since many potential food allergens are valuable sources of nutrients and fiber, seek guidance from your doctor or dietitian before eliminating them completely from your diet.