Switching from a “Western” diet with lots of fat and meat to a fiber-rich diet for just two weeks makes conditions in the large intestine less favorable to the development of colon cancer. The opposite switch may promote the formation of cancer. That’s the conclusion from a small but elegant study done in urban Pittsburgh and rural KwaZulu-Natal, South Africa. In the study, 20 volunteers from each area switched diets. For two weeks, the Americans ate a traditional high-fiber African diet rich in fruits, vegetables, nuts, and beans, while the Africans ate a Western diet with more fat, protein, and meat. In just two weeks, significant changes occurred in the lining of the colon and in its chemical and bacterial make-up in both groups, but in different directions. Those following the African diet showed improvements in colon health likely to protect against colon cancer, while those following the Western diet showed changes that could lead to colon cancer.
This week’s inaugural April Fool’s Day edition of JAMA Internal Medicine carried a report entitled “Association Between Apple Consumption and Physician Visits: Appealing the Conventional Wisdom That an Apple a Day Keeps the Doctor Away.” Based on actual national nutrition data collected from nearly 8,400 men and women it concludes, “Evidence does not support that an apple a day keeps the doctor away; however, the small fraction of US adults who eat an apple a day do appear to use fewer prescription medications.” Apples may have failed this critical scientific test, but they are still an excellent choice as a snack, pick-me-up, or dessert.
Looking for ways to ward off colorectal cancer? According to a new study, a pescovegetarian diet — that’s a vegetarian diet that includes fish — was linked to a 43% reduction in the risk of developing colorectal cancer. The study, published in JAMA Internal Medicine, adds more support to the notion that something in red meat, or the way it is cooked, encourages the growth of colorectal cancer. It’s also possible that eating more plant foods provides extra beneficial nutrients such as folate, calcium, and fiber that may protect against colorectal cancer. Fish contain healthful omega-3 fats and vitamin D. Another good strategy for preventing harm from colorectal cancer, the second leading cause of cancer death in the United States? Have colonoscopies as needed.
Nuts have been gaining traction as an all-natural health food. Tree nuts like almonds, pecans, and walnuts are especially prized for their rich cargo of vitamins, minerals, and mono- and polyunsaturated fats. The downside is that tree nuts tend to be pricey. But a study published online this week in JAMA Internal Medicine puts the humble peanut squarely in the same nutritional league as its upscale cousins. This work makes the health benefits of nuts more accessible to lower-income shoppers. An international team of researchers found that in more than 200,000 people from Savannah to Shanghai, those who regularly ate peanuts and other nuts were substantially less likely to have died of any cause — particularly heart disease — over the study period than those who rarely ate nuts. A key take-home message from this study is that eating peanuts appears to be just as potent for preventing heart disease as eating other nuts.
Peanut allergies can cause severe and sometimes deadly allergic reactions. A new study holds out the possibility that peanuts themselves may prevent peanut allergies. An international team asked parents of infants who were prone to a peanut allergy to give their children a peanut-based snack called Bamba or peanut butter three times a week until age five. The parents of another group of peanut allergy-prone infants were asked to make sure their children didn’t eat any peanuts, peanut butter, or other peanut-based products until age five. The results were surprising and dramatic. A peanut allergy developed in 1.9% of children who ate Bamba or peanut butter, compared with 13.7% of those who didn’t eat peanuts. This new work suggests that preventing peanut allergies may be a possibility in the near future.
Getting to a healthy weight and staying there isn’t always easy. Many complicated diets offer solutions. A study published in today’s Annals of Internal Medicine suggests that something as simple as aiming to eat more fiber each day can be just as good as a more complicated diet. In a head-to-head study of a simple diet (eat more fiber) and a complex one (eat more fruits, vegetables, high-fiber foods, fish, and lean protein but also cut back on salt, sugar, fat, and alcohol), participants lost almost the same amounts of weight on either diet. Both diets led to similar improvements in blood pressure the body’s response to insulin. The results of the study don’t prove that a high-fiber diet is necessarily as good (or better) for health than the AHA diet or the highly in-vogue Mediterranean diet. But it does suggest that one simple step can make a difference and that encouraging healthy behaviors may be more effective than discouraging unhealthy ones.
Nearly 2 billion people around the world are anemic, meaning they don’t get enough iron to produce the red blood cells and oxygen-carrying hemoglobin needed to nourish their myriad cells. In developed nations like the United States, though, iron-poor blood is uncommon. The body stores most of its iron in hemoglobin inside red blood cells and in ferritin, a protein that latches onto iron and sequesters it in the liver, spleen, and bone marrow. Most Americans get all the iron they need from food. The body absorbs iron from meat more easily than it absorbs it from plants. Getting enough vitamin C helps the body absorb iron from food. Because the body does not excrete iron rapidly, it can build up over time and possibly cause problems. That’s why it’s a good idea to ask your doctor if you need to take an iron supplement.
One way to avoid adding extra pounds over the holiday season is by relying on the glycemic index to choose your foods and snacks. The glycemic index is a measure of how fast carbohydrates are turned into sugar. The higher a food’s glycemic index, the faster your body turns that food into sugar, and the sooner the “hunger bell” rings again. This can set into motion the cycle of holiday overeating. One way to go low glycemic: Choose foods your grandmother used to eat—ones that resemble things in nature, and don’t come with long lists of ingredients.
The results of a clinical trial reported in yesterday’s Annals of Internal Medicine showed that low-carb diets helped people lose weight better than low fat diets. A report in today’s Journal of the American Medical Association tells a somewhat different story. A review of 48 head-to-head diet trails showed that average weight loss on either a low-carb or low-fat diet for 12 months was the same, about 16 pounds. And when the researchers compared named diets, which ranged from the low-carb Atkins and South Beach diets to moderates like Weight Watchers and Jenny Craig and low-fat approaches like the Ornish diet, all yielded similar weight loss. The main message from careful comparisons of different diets is that there’s no single diet that’s right for everyone. Any healthy diet can help people lose weight. And there’s more to a diet than weight loss. What’s needed for long-term health is an eating plan that can be followed day in and day out that is good for the heart, bones, brain, and every other part of the body. One eating strategy that can provide all that is the so-called Mediterranean diet.
We often look to science to solve life’s difficult questions. But sometimes it hands us more uncertainty. Take three reports in today’s New England Journal of Medicine. One shows that eating less sodium (a main component of salt) could save more than a million lives a year worldwide. A second came to a nearly opposite conclusion — that current average sodium intake is okay for cardiovascular health while getting either too little or too much is a problem. The third study essentially agreed with the second, but found that getting too little potassium may be as bad as getting too much sodium. The findings are certain to fuel the already heated debate on sodium and the international efforts to get people to take in less of it. But until there are good answers to the questions raised by the studies, it’s too soon to throw out recommendations to reduce sodium intake, especially in high-risk groups. Another lesson from the three New England Journal articles worth keeping in mind: getting more potassium from fruits, vegetables, and other foods is a good way to help keep your heart and arteries healthy.