Soda / Pop
Several studies, including one major one from the American Journal of Nutrition found that those who consumed more than 1 serving of soda a day are at an increased risk of stroke than those who avoid soda pop. What is more alarming is that because of the high amounts of sugar present in soda, it is part of the obesity epidemic that has struck America. When you drink a lot of sugar, the influx of simple carbohydrates causing your blood glucose to spike, increasing inflammation in the body and the tendency to develop insulin resistance. The end result is usually diabetes.
Epidemiological evidence suggests that diabetes increases the risk of cancer exponentially. Many pancreatic patients, for instance, have an intolerance to glucose. Cancer rates are higher in individuals with both type 1 and type 2 diabetes.
Lastly, sodas usually contain artificial coloring and chemicals, like 4-methylimidazole (4-MI), a known carcinogen.