Health experts believe that cancer risk is related to many things that are within our control , such as diet, exercise, body weight, and tobacco use. And among the different cancer types, colon cancer appears to be most strongly influenced by health, lifestyle, and food choices.

New research suggests that a particular Asian diet staple contains nutrients that may be particularly good for keeping colon cancer at bay. Soy foods, eaten for thousands of years in Asia, and more recently added to the diet in the United States and Europe, contain nutrients called sphingadienes (sfing-ah-die-eens), or SDs.

It turns out that SDs can encourage damaged cells - the type of cells that can develop into cancer - to die, rather reproduce. The latest study suggests that SDs are particularly useful in colon cancer prevention. As well, these nutrients may help researchers develop medications for cancer treatment.

Soy Smart

Is soy for you? Unless you have a medical reason to avoid soy, such as a food allergy, soy can be a healthful addition to your diet. The best way to incorporate soy into your diet is to stick to whole soy foods. You want to get most of your soy from what is found in traditional, healthful, Asian diets, such as tofu, tempeh, and miso. Soy milk also can be used to add soy into your eating routine.

Whole soy foods are best because these are the foods that have been eaten for thousands of years in many places throughout the world. We know they are healthy and safe to eat. And these are the same foods that research suggests have the best cancer prevention activity. They are natural, they are minimally processed, and they are a good source of SDs and other beneficial nutrients.

You should not load up on soy supplements, powders, or pills. Also steer clear of a lot of soy-fortified or soy-infused processed foods, such as chips and crackers made with soy and high-sodium soy "meat". Enjoying small amounts of these processed soy foods in moderation is fine, but like all processed food, they contain a lot of salt (sodium) and preservatives, neither of which are good in large amounts.

It's been known in the medical community in the US for some time that people in certain race/ethnicity groups appear to do better, and in some cases worse, than whites (Caucasians or people of European ancestry) in terms of survival after cancer diagnosis. This is true of colon cancer, with research showing that African Americans have worse survival rates than Caucasians.

The important question is why some groups of people in general fare worse with cancer than whites. If health experts can figure out why, they can tackle the problem and focus on improving cancer survival rates for African Americans, and possibly for everyone else too.

Why Are There Differences in Colon Cancer Survival?

Some of the difference in colon cancer survival rates among various groups of people may be due to differences in other factors that affect health, such as individual and tumor genetics, access to health care, the presence of other health conditions and diseases, and obesity. But the latest research on this issue suggests that these factors do not explain all of the difference in survival rates between African Americans and Caucasians.

Weight Still Matters for Colon Cancer Survival

The study did show that among all people with colon cancer, regardless of race/ethnicity, a higher body mass index (BMI) means a lower chance of survival. BMI, a measure of weight in relation to height, is a number that is used to determine if someone is overweight or obese. Obesity is defined as having a BMI of 30 kilograms per meter squared (kg/m²) or more. So regardless of your race, being overweight when you are diagnosed decreases the chances of a complete cure after colon cancer.

But even taking into account that African Americans have higher rates of obesity than Caucasians, BMI still doesn't explain all of the differences in survival between these two groups. This means that more research is urgently needed to get to the bottom of this question, and to find ways to make sure that all people, including African Americans, have the best possible chance of surviving colon cancer.

Where Weight Helps

One interesting aspect of the body weight-colon cancer connection that this study uncovered surprised the researchers, but I don't think it should have. They found that for advanced (stage IV) cancer, being overweight decreased the risk of death. This isn't as strange as it may seem.

Stage IV colon cancer is not considered curable, which means that as it progresses, people are likely to become sicker and more frail over time. Having a little extra "cushion" in the form of body weight likely protects people from experiencing malnutrition as their cancer becomes more advanced. In some cases, advanced colon cancer makes it more difficult to eat enough, and in these cases, being overweight would help you live longer and stronger.

The Bottom Line

But the bottom line is that overall, being overweight increases your risk of being diagnosed with colon cancer. And being overweight decreases your likelihood of survival if you are diagnosed with anything but the most advanced type (stage IV) of colon cancer.

If you are living with colon cancer and you are overweight, don't embark on a crash diet or extreme weight loss plan. This is not healthy and won't help you heal and get through treatment. Instead, talk to your doctor about ways you can live as healthfully as possible during and after treatment. Ask for a referral to a dietitian who can work with you to develop a healthy eating plan that will get your body the nutrients it needs.

A dietitian who specializes in working with cancer patients can help you use good nutrition to address any symptoms, side effects, or limitations on the foods you can eat due to your cancer and its treatment. A dietitian can help you develop a long-term, healthy nutrition plan to get you back to health after cancer as well.

The National Cancer Institute (NCI) is known by many people as the arm of the National Institutes of Health that funds research on the prevention, causes, and treatment of cancer.

Now the NCI is creating resources for people living with or affected by cancer and has much helpful information to share. In the newly created Supportive and Palliative Care section of the NCI website, you will find information on a variety of helpful areas, including:

• physical side effects of cancer and its treatment
• emotional effects of cancer
• advice for caregivers, family, and friends of those living with cancer
• children and cancer
• finding good cancer care
• the financial and legal impacts of cancer
• cancer survivorship
• clinical trials on palliative and supportive cancer care

Of course you can find much of the same information and more, right here on About.com, and I encourage you to do so. But I also believe that information and knowledge are something you can never have enough of when facing a diagnosis of cancer. Knowledge can give you what you need to make smart, informed choices about how best to treat, manage, and cope with cancer.

When it comes to cancer prevention, it's wise to steer clear of most supplements and instead focus on food. Numerous studies have suggested that many dietary supplements do not decrease cancer risk. Some supplements, in fact, actually may increase risk, raising concerns that supplements cause more harm than good for many people.

The latest study on this topic adds to these concerns with the finding that folic acid and vitamin B₁₂ dietary supplements increase the risk of being diagnosed with cancer, of dying from cancer, and of dying from any cause.

By the Numbers

The study was a double-blind, placebo-controlled, randomized clinical trial in which nearly 7,000 adults in Norway were randomly selected to take one of the following:

• 0.8 mg of folic acid + 0.4 mg of vitamin B₁₂ + 40 mg vitamin B₆ per day
• 0.8 mg of folic acid + 0.4 mg of vitamin B₁₂ per day
• 40 mg vitamin B₆ per day
• placebo (no vitamins)

Double-blind means that neither the researchers nor the study participants knew who was taking which vitamins or the placebo. Randomized means that people were selected at random for each vitamin (or placebo) group. This type of study is considered "the gold standard" of research designs, because it is most likely to show results accurately, without errors that can happen with other study designs.

Study participants were followed for a median (similar to average) of approximately six and a half years (39 months of active study participation plus 38 months of post-study observation). The study showed that compared with people not receiving folic acid and vitamin B₁₂, those who took these vitamins had:

• 21% higher risk of being diagnosed with cancer (any type)
• 38% higher risk of dying of cancer (any type)
• 18% higher risk of dying of any cause

Taking vitamin B₆ did not have any measurable effects (good or bad) on the health of the study participants.

Take Home Message

It is likely that most of the negative health effects shown in this study are related to folic acid, more than to vitamin B ₁₂. Health experts have suspected for some time that folic acid may be a "double-edged" sword.

If people get plenty of folic acid early in life, including in the womb (in utero, during pregnancy) and through childhood, this appears to protect against later developing cancer. If, however, people get too much (excess) folic acid during adulthood, this seems to increase the overall risk of cancer, and of colon cancer in particular.

Also of note: This study showed harm from folic acid supplements in a country that does not fortify its food supply with folic acid. The United States does fortify the food supply with folic acid. This means that we already get a supplemental form of this nutrient in our diets in high amounts. This also means that the harms of taking additional folic acid supplements are more likely to occur in people who are living in the US.

The bottom line is that we should get our folic acid from foods naturally high in this nutrient, not from pills. No studies have ever shown that getting plenty of folic acid from food increases cancer risk. Plus, studies do show that eating folic acid-rich foods likely decreases cancer risk. The same is definitely not true of folic acid supplements.

Taking folic acid as a dietary supplement is not a good idea, unless advised to do so by your doctor, for a specific medical reason, such as pregnancy. Eating foods that are naturally rich in folic acid (not foods that are fortified) is a good idea for everyone, because these are the same foods that appear to reduce cancer risk when part of a healthy diet.

Healthy Eats

The best, natural food sources of folic acid include:

• black-eyed peas (beans)
• pinto beans
• chickpeas (garbanzo beans)
• spinach
• okra
• black beans, navy beans, and other beans
• asparagus
• collard greens
• kale
• chard
• other green leafy vegetables
• broccoli
• artichokes