Supergreens Green Drink

Alkaline means they have pH lower than 7 (a base), while acidic foods have pH higher than 7.
Alkaline foods usually have hydroxides in them, such as green vegetables. The hydroxides (base) have a bitter flavor.
Acidic foods are usually sour because of the acid, and these include fruits, vinegar, coffee, etc.

The question of whether cancer can or cannot grow in acidic environment aside...
If you want to attain an acidic environment in your body, why the heck would you be eating alkaline foods? It will just make your body alkaline, not acidic.

Fresh fruit, vegetables, roots and tubers, nuts, and legumes , carbohydrate-rich starch foods like rice, grains and potatoes.
Avoid grains, dairy, meat and excess salt.
But again, it is in your best interests that you talk to your doctor and a dietician about alkaline foods before embarking on this diet.