If you’re like most cancer survivors, you’re always looking for ways to improve your quality of life and your chances of long-term survival. That’s smart! But use caution when you read news that challenges conventional wisdom.

The best advice about diet is that it is rarely a good idea to change it based on a single study or news report. The following questions and answers address common concerns of cancer survivors regarding diet:

Alcohol: Does It Increase Risk of Recurrence?

We know that drinking alcohol, especially heavily, increases a person's risk for cancer of the mouth, throat, larynx, esophagus, liver, breast, and probably colon. But alcohol intake could also affect the risk in people who have already been diagnosed with cancer: the more they drink, the higher their risk for new cancers at the same sites. And because alcohol can increase levels of estrogens in the blood, some experts think it might increase a woman's risk for recurrence of estrogen receptor-positive breast cancer. Studies are still out on this theory.

Antioxidants: Can They Help Prevent Cancer?

Antioxidants are substances in the body that help slow down or prevent cell damage from oxidation – that is, from chemical reactions with oxygen. Vitamin C, vitamin E, carotenoids, and many phytochemicals are a few common antioxidants.

Because this cell damage may be important in the development of cancer, it has long been thought that antioxidants, by slowing or stopping this damage, may actually be able to help prevent cancer.

It's not that simple, of course. It matters whether the antioxidants come from food sources or from a pill. People who eat antioxidant-rich vegetables and fruits may have a lower risk for some types of cancer, studies suggest, but those benefits appear to be lost when the antioxidants come from vitamins and mineral supplements instead of food. For that reason, cancer survivors, who may be at increased risk for second cancers, would probably be better served by making sure antioxidant-rich foods are a regular part of their diet, rather than relying on multivitamins or some other non-food source.

Fat: Does Eating Less Lower the Risk of Recurrence or Improve Survival?

There is little evidence that total fat intake has a direct effect on cancer risk or recurrence. However, diets high in fat tend to be high in calories, and high-calorie diets contribute to obesity. Obesity, in turn, is linked to increased risk of several types of cancer, as well as increased risk of recurrence and reduced chances of survival for many cancer sites.

Studies looking more closely at certain types of fat have found some evidence that saturated fats may contribute to increased cancer risk. On the other hand, there is little evidence that other types of fat – such as omega-3 fatty acids from fish or mono-unsaturated fats found in olive and canola oils – reduce cancer risk.

Consuming excess amounts of saturated fat, of course, is a known risk factor for heart disease, a major cause of death in all populations, including cancer survivors.

Although trans fats, such as margarines and partially hydrogenated oils, have harmful effects on the heart, their link to cancer risk or survival is not clear. Regardless, cancer survivors (especially those at increased risk of heart disease) should eat as few trans fats as possible.

Fiber: Will Eating More Prevent Cancer or Improve Survival?

Dietary fiber is the part of plant foods that cannot be easily digested by humans. Foods that are especially rich in dietary fiber include beans, certain vegetables, such as broccoli and carrots, whole grains, and some fruits, particularly apples and bananas.

Fiber helps lower the risk of heart disease by reducing blood cholesterol levels, and it is linked to improved bowel function. The links between fiber and reduced cancer risk are weak. Nevertheless, eating foods like those listed above is still a good idea because they contain other nutrients that may help reduce cancer risk and provide other health benefits.

Meats: Should They Be Avoided?

Several studies have linked eating large amounts of red meat and processed meat with increased risk of colorectal, prostate, and stomach cancers. Some research also suggests that frying, broiling, or grilling meats at very high temperatures creates chemicals that increase the risk of some types of cancer.

But no studies have looked at the effect of consuming processed or red meat or meat cooked at a high temperature on cancer recurrence or progression. In lieu of those studies, the American Cancer Society recommends you follow its general guidelines for cancer prevention and limit the amount of red meat and processed meat in your diet.

Obesity: Does It Increase Risk of Recurrence or of Getting Another Type of Cancer?

Mounting evidence suggests that being overweight not only raises the risk for recurrence, but also reduces the odds of survival for many cancers. For all cancers combined, obesity has been linked with higher death rates.

It has also been linked with increased risk for cancers of the esophagus, colon and rectum, liver, gallbladder, pancreas, and kidney; for non-Hodgkin lymphoma and multiple Myeloma; and for cancers of the stomach and prostate in men and of the breast, uterus, cervix, and ovary in women.

Because there are also other proven health benefits of a healthy weight, people are encouraged to avoid weight gain in the first place and to lose weight if they are too heavy.

Organic Foods: Are They Recommended for Cancer Survivors?

Oganic foods are commonly thought to be healthier because they reduce our exposure to some chemicals used in commercial agriculture. And some suggest their nutrient composition may be better than non-organic foods. Whether either claim is true and, if so, whether that translates into health benefits, is unknown.

At this time, no studies in humans have shown that organic foods are better at reducing cancer risk, recurrence or progression than foods made by other farming and production methods.

Soy-Based Foods: Do They Reduce Cancer Risk?

There is a great deal of interest in the possible role of soy foods in reducing the risk of cancer in general and of breast cancer in particular, but the evidence for such a role is mixed.

Soy-derived foods are an excellent source of protein and can be a good alternative to meat. Soy also contains several phytochemicals, some of which have weak estrogen activity and seem to protect against hormone-dependent cancers in animal studies. Still other compounds in soy have antioxidant and other helpful properties.

For the breast cancer survivor, current research suggests neither specific benefits nor harmful effects when soy is consumed in moderate amounts – no more than three servings per day – as part of a healthy diet. But higher doses of soy may have estrogen-like effects, and higher levels of estrogens clearly increase the risk for progression of some breast cancers. Therefore, it is prudent for breast cancer survivors to avoid the high doses that are found in more concentrated sources such as soy powders and isoflavone supplements.

Sugar: Does It Feed Cancer?

In a word, no. Sugar intake has not been shown to directly increase the risk of getting cancer or having it progress. But sugars and beverages that contain them add large amounts of calories to the diet and can cause weight gain, which can affect cancer outcomes. Therefore, limiting sugar intake is recommended.

Vegetables and Fruits: Do They Lower the Risk of Cancer Recurrence?

A diet rich in vegetables and fruits has been linked in most studies with a lower risk of getting lung, oral, esophagus, stomach, and colon cancers. But few studies exist on whether such a diet can reduce the risk of cancer recurrence or improve survival in general. Some recent studies suggest that an increased intake of vegetables may have a helpful effect on recurrence or survival for breast, prostate, and ovarian cancers, but this is not definite.

Despite the absence of definitive conclusions, cancer survivors are encouraged to eat at least five servings of an array of vegetables and fruits each day because of the other known health benefits of such a diet. Because it is not known which of the compounds in vegetables and fruits are the most protective, the best advice is to consume five or more servings of a variety of colorful vegetables and fruits each day.

Although fresh, frozen, and canned vegetables and fruits all have different nutritional values, they can all be good choices.

And even though fresh foods are usually thought to have the most nutritional value, frozen foods can in fact be more nutritious than fresh because they are often picked ripe and quickly frozen. With fresh food products there can sometimes be considerable time between harvest and eating.

Canning is more likely to reduce the heat-sensitive and water-soluble nutrients because of the high temperatures needed in the canning process. The best recommendation is to choose vegetables and fruits in a variety of forms and to cook them in the microwave or steam them.

Vegetarian Diets: Do They Reduce the Risk of Cancer Recurrence?

No direct evidence has shown that a vegetarian diet is any more beneficial for reducing cancer recurrence than a diet high in vegetables, fruits, and whole grains, and low in red meats. Vegetarian diets, however, can have many healthful traits because they tend to be low in saturated fat and high in fiber, vitamins, and phytochemicals, and they are consistent with the American Cancer Society nutrition guidelines for the prevention of cancer.

Water and Other Fluids: Can They Reduce the Risk of Cancer?

Drinking water and other liquids may reduce the risk of bladder and colon cancers. Drinking at least eight cups of liquid a day is usually advised for the general public and is reasonable advice for survivors, too, with the exception of those who have a specific medical reason for restricting fluid intake.

Click here to get more information on this subject from the American Cancer Society's online bookstore.