In an effort to guard against cancer, you might consider adding a multivitamin to your menu of blueberries, broccoli and whole grains.
Men who took a daily multivitamin had an 8 per cent reduction in cancer risk compared to their peers who didn't take the supplement, according to a study published online last week by the Journal of the American Medical Association.
Earlier studies that investigated the link between multivitamin use and cancer risk have turned up mixed results suggesting no relationship, protective effects, or potential harm.
The current study is the first large scale, randomized controlled trial (the Physicians Health Study II or PSH II) to test the long-term effects of a common multivitamin in the prevention of chronic disease. The researchers had 14,461 middle-aged and older men take either a multivitamin and mineral supplement or placebo for 11 years.
Overall, multivitamin users had a modest, but significant, 8 per cent reduction in risk of total cancers compared to men taking a placebo. Taking a daily multivitamin did not alter the risk of prostate cancer. The risk of dying from cancer was also not different between the two groups.
The protective effect of multivitamins was stronger in men aged 70 or older, in men with no parental history of cancer, and in men with a history of cancer. Multivitamin use was associated with a 27 per cent lower cancer risk in men with a history of cancer prior to the study.
It's not clear which vitamins and minerals in a multivitamin supplement may have anti-cancer effects. For the most part, earlier trials that tested the effect of selected vitamins or minerals, in higher doses, found no benefit. The PSH II results suggest that a broad combination of low-dose nutrients in a multivitamin – rather than high dose single nutrients – is what's important for cancer prevention.
Do the current findings mean everyone should rush out to buy a multivitamin in the hopes of warding off cancer? No. For starters, it's not known if these results also apply to women or men younger than 50. And if you are already well-nourished, adding a multivitamin to your regime may not give you extra protection.
That said, it can't hurt to add a one-a-day supplement to your routine especially if you need to bridge nutrient gaps in your diet. And if you're a male aged 50 or older, it's possible that doing so can modestly lower your cancer risk.
First and foremost, however, adopt lifestyle habits that are convincingly linked to cancer prevention. The following measures have strong evidence for their cancer-fighting effects.
Maintain a healthy weight
Carrying excess body fat, especially around the middle, increases the risk of many cancers including esophagus, pancreas, colon, breast (post-menopausal women), endometrium and kidney.
Fat cells produce hormones and other proteins that can promote cell growth that could lead to cancer.
If you're overweight, take action to achieve a healthy body-mass index (BMI). If you're at a healthy weight, avoid weight gain and increases in waist circumference throughout adulthood.
Data strongly suggests that physical activity protects against colon cancer, post-menopausal breast cancer and endometrial cancer.
Being sedentary – too much sitting – is also linked to a greater risk of certain cancers. Prolonged sitting influences key indicators of cancer risk including waist circumference, inflammation and insulin resistance. (Insulin resistance is a condition in which cells are unable to use insulin properly.)
Get moderate physical activity (e.g. brisk walking) at least 30 minutes daily. As your fitness improves, aim for 60 minutes or more of moderate, or 30 minutes or more of vigorous (e.g. jogging, stair climbing), physical activity every day.
Limit sedentary activities like television watching. Break every hour of sitting with one to two minutes of activity.
Limit red meat
There's convincing evidence that heavy intakes of red meat, especially processed meat, increase colorectal cancer risk.
Cooking meats to high temperatures (e.g. grilling sausages or frying bacon) forms compounds shown to cause colon tumours in animals. The form of iron in meat – heme iron – may also damage colon cells and trigger cancer growth.
Processed meats (e.g. ham, corned beef, bologna, wieners) also contain sodium nitrite, which can react with compounds naturally present in meat to form N-nitroso compounds, several of which have been associated with certain cancers in humans and animals.
Limit your intake of red meat – beef, pork, lamb, goat – to less than 18 ounces per week.
Eat a plant-based diet
Vegetables, fruits, whole grains and other high-fibre foods are thought to protect against a number of cancers. Eat at least five servings of fruits and vegetables (combined) each day, and preferably more.
Include whole grains or legumes (e.g. beans, lentils) at every meal. Minimize your intake of refined (white) grains.
If consumed at all, limit alcohol drinks to two per day for men and one for women. And, of course, don't smoke.
Leslie Beck, a registered dietitian, is the national director of nutrition at BodyScience Medical. She can be seen every Thursday at noon on CTV News Channel's Direct. www.bodysciencemedical.com.