Week of June 4, 2012
Contact: Alice Bender, (202) 328-7744

AICR HealthTalk
Karen Collins, MS, RD, CDN
American Institute for Cancer Research

Q: I get the government’s weekly recommended amount of physical activity (150 minutes, moderate activity and strength training on 2 days). Does it matter whether it’s all on the weekend or spread throughout the week?

A: First, bravo for getting the recommended amount of physical activity! Physical activity acts in many different ways to improve your health, sense of well-being and energy. If you are focused on burning calories for weight management, the average over a week’s time is what seems to count. However, you might miss out on some important additional benefits by concentrating physical activity in just two sequential days. For example, high levels of the hormone insulin seem to act like a growth factor promoting cancer development, but physical activity can reduce excessive levels of the insulin. And studies show that physical activity’s action on insulin levels lasts from 24 to 72 hours. That’s why the American Diabetes Association recommends that you don’t go more than two consecutive days without some physical activity. Furthermore, other health benefits of physical activity, including its positive impact on mood, energy and concentration, do not seem able to be stockpiled a week at a time. Perhaps you mean that the weekend is the only time that you “exercise” – as in sports or yard work. That’s fine, but you can also walk or bicycle instead of drive on an errand, turn on some music and dance, or just take a walk for even 10 to 15 minutes once or twice every day in addition to enjoying larger periods of activity on the weekend. Remember that while 30 minutes a day is the recommended minimum for good health, health benefits are even greater when you work up to an hour a day of moderate activity (or 30 minutes of vigorous activity like running or more intense sports).

Q: Do the bacteria in our gut really affect health? If so, can probiotics help?

A: Yes, research suggests that gut bacteria may affect your health, including chronic inflammation (in the gut and throughout the body), colon cancer risk and even weight control. People do have different types of bacteria in their digestive tract, but changes in diet can alter the proportions of these bacteria in our gut within days or weeks so your overall diet is important. Diets with mostly vegetables, fruits, whole grains and beans provide compounds called polyphenols that in cell studies support growth of health-promoting bacteria and inhibit less desirable bacteria. Diets high in meat seem to encourage more gut bacteria that promote compounds that damage colon cells, and less of the health-promoting bacteria. Probiotics are live organisms that offer a health benefit for our gut and are part of, or added to, food and supplements. Foods that contain probiotics include fermented dairy products (yogurt, cheese and kefir), sauerkraut, kimchi (a spicy Korean condiment made from fermented cabbage), the fermented soy products miso and tempeh, and certain salt-cured pickles and olives. Studies show that foods with prebiotics that support growth of healthy bacteria may be more effective than probiotics. Prebiotics are certain types of carbohydrate such as inulin (found in onions, garlic, asparagus, Jerusalem artichokes, bananas, chicory and artichokes) and fermentable dietary fiber and resistant starch you get from dried beans and peas and certain whole grains.

Our Mission: The American Institute for Cancer Research champions the latest and most authoritative scientific research from around the world on cancer prevention and survival through diet, weight and physical activity, so that we can help people make informed lifestyle choices to reduce their cancer risk.

We have contributed over $105 million for innovative research conducted at universities, hospitals and research centers across the country. Find evidence-based tools and information for lowering cancer risk, including AICR’s Recommendations for Cancer Prevention, at


All active news articles