Diet and Cancer page 2

Vitamin E

We recommend that adults take 400-800 IU of vitamin E each day in supplement form. Although it would be better to get it from dietary sources, it is practically impossible to get this amount directly from food. Like other fat-soluble vitamins, it should be taken with some dietary fat for better absorption (such as whole milk, for example). What kind of vitamin E you take is very important. The most commercially-available form of vitamin E is alpha-tocopherol (α-tocopherol). Ideally, you should get a vitamin E supplement that contains all four forms of tocopherol (alpha, beta, gamma and delta) and maybe a little tocotrienol if possible. If you can't find one with all for forms, the next best thing is one that contains the alpha- and gamma- forms.

The Institute as well as many other doctors and researchers recommend the natural form of vitamin E because it is much more powerful and better absorbed than the synthetic version. The natural version can be recognized because there is a "d-" in front of the kind of vitamin E. For example, the natural version of alpha-tocopherol is labeled "d-alpha tocopherol" or "d-α tocopherol". The synthetic version is labeled "dl-alpha tocopherol". The natural form costs about twice as much as the synthetic version, so do your own math and figure out which one you want to take.

Tocotrienol supplements are expensive, so most people won't want to bother with them. However, you can get some of your tocotrienols from bran, so if you eat bran cereal each day, you will be killing two birds with one stone: you will be obtaining the difficult to find tocotrienols and you will be reducing your colon cancer risk (and that of other cancers) by eating fiber.

Being fat-soluble means that it can accumulate in your body fat. However, unlike other fat-soluble vitamins, vitamin E is relatively non-toxic. Studies have shown that amounts of 800 IU are safe over long periods of time. People at risk for prolonged bleeding such as those with blood coagulation problems probably should avoid vitamin E supplements because it decreases the ability of blood to clot and can therefore lead to excessive bleeding. Consult with your doctor if you have any doubts about vitamin E in general or if you are at risk of prolonged bleeding in particular.

Vitamin A

We recommend that adults take 10,000 IU of vitamin A supplements each day in addition to the vitamin A that they may obtain from food. Ideally, you should try to get much of your vitamin A from natural food sources, but it is unlikely that the entire amount can be obtained from food. Because it is fat-soluble, it is best to take it along with some dietary fat in order to increase its absorption.

Vitamin A can be obtained from dark red, green or yellow vegetables, including carrots, cantaloupe, tomatoes, and spinach. It can also be obtained from diary products, liver, fish liver oil, and eggs. If you eat a lot of these foods, you should probably take a supplement in a dose that is at the lower end of the recommended range.

Vitamin A toxicity can result from doses in the 50,000 IU range, although there have been very few reported cases of vitamin A toxicity that resulted in any serious consequences. Severe toxicity can lead to blindness or even be life-threatening, and can lead to liver damage for children that take excessive doses over long periods of time. Also, pregnant women should not take doses that are greater than the recommended daily allowance (2,600 IU) because it can lead to birth defects in their babies. The symptoms of vitamin A overdose include: dizziness, nausea, vomiting, headache, joint pain, skin irritation, and, in women, infrequent periods. Should you experience any of these symptoms, please consult with your physician.

Folic acid (folate)

Folic acid supplementation is highly recommended, especially for women, although it also has important protective effects for men. The best natural source is green leafy vegetables, so you should have a lot of salads, but supplements are probably required by most people. We recommend that adults take 1,000 mcg (micrograms, not milligrams) of folic acid each day. Since it is so inexpensive, there is no excuse for not taking this important supplement.

Folic acid reduces vitamin B12 levels, a reduction of which can cause serious problems, so vitamin B12 supplements should be taken when taking folic acid. It is believed that folic acid supplements might interfere with the chemotherapy drug Methotrexate, so if you are undergoing treatment with it the prudent thing would be to avoid folic acid supplementation and to consult with your doctor.