As we saw on the last page, calcium is important for strong teeth, which makes sense as teeth are, in effect, bone. But to absorb calcium, the body needs vitamin D, which it uses to produce a hormone known as calcitriol. If you are under the age of 70 you should strive to get 600 International Units (IU) of calcium a day -- and should increase that to 800 IU daily if you are older [source: NIH Osteoporosis and Related Bone Diseases National Resource Center]. Vitamin D can be found in egg yolks, liver, fatty fish like salmon, tuna and mackerel, and fortified milk. It can also be obtained from sun exposure and from supplements.
Vitamin A is another bone-booster that can help to keep teeth strong. It can be found in both animal-based food sources such as eggs, liver and milk or in plant sources -- most commonly as beta-carotene -- such as vegetables like carrots, sweet potatoes, spinach and cantaloupe.
Super-strong teeth aren't really of very much use if they're anchored in unhealthy gums, which is why you want to make sure you are also getting enough vitamin C. This popular vitamin helps keep connective tissues -- like gums -- healthy. Good sources of vitamin C include all citrus fruits, strawberries, broccoli, peppers and tomatoes, as well as many other fruits and vegetables.