Some food combinations that should be avoided according to Ayurveda:

•  Avoid taking milk or yogurt with sour or citrus fruits.
•  Avoid eating fruits together with potatoes or other starchy foods. Fructose (and other sugars) is digested quickly, whereas starch takes quite some time. In this case the sugar would not be properly digested.
•  Avoid eating melons and grains together. Melons digest quickly whereas grains take more time. This combination will upset the stomach. Melons should be eaten alone or left alone. Honey should never be cooked. Honey digests slowly when cooked and the molecules become a non-homogenized glue which adheres to mucous membranes and clogs subtle channels, producing toxins. Uncooked honey is nectar. Cooked honey is poison.
•  Do not eat meat protein and milk protein together. Meat is heating and milk is cooling so they counteract one another, disturb agni and produce ama.
• Milk and melons should not be eaten together. Both are cooling, but milk is laxative and melon is diuretic, and milk requires more time for digestion. Moreover the action of hydrochloric acid in the stomach causes the milk to curdle. For this reason Ayurveda advises against taking milk with sour fruits, yogurt, sour cream, cheese, and fish.