If you eat sugar frequently, you may get frequent colds. Sugar has a direct impact on the immune system.
This isn’t an article for getting technical, but sugar triggers high levels of the hormone insulin. Some people are especially sensitive to sugar and may secrete extra-high levels of insulin when they eat it.
In turn, the insulin can trigger the production of inflammatory substances in the body, such as cytokines and series 2 prostaglandins. Inflammation is currently medically recognized as the root cause of most, if not all, disease.