Sugar consumption has been associated with heart disease, autoimmune disease, diabetes, irritable bowel disease, chronic fatigue, candida, and many pain-related conditions. Sugar can inhibit the absorption of vitamin C into white blood cells, causing reduce immunity. 

Sugar in all forms should be avoided, or limited as much as possible. This includes white and brown sugar substitutes. Countless low-fat meals have artificial sugars added, and there is evidence to show that these artificial sugars have adverse side effects.