SCIENTIFIC UPDATE
By Reed Mangels, PhD, RD
More Meat Associated with Increased Diabetes Risk
More people in the U.S. are being diagnosed with type 2 diabetes, formerly called adult-onset diabetes, which can lead to a greater risk of heart disease, eye problems, and kidney disease. Several studies have found that people who eat more red meat have a higher risk of type 2 diabetes. What about people who increase the amount of meat they consume, perhaps because they're on the Paleo diet or simply want more meat? A study of more than 150,000 people looked at how their meat consumption changed over a 4-year period and the effect of changes on diabetes risk. The results were sobering. Compared with those who ate fewer than 2 servings of red or processed meat weekly and whose meat consumption was stable, those who increased their red or processed meat intake by more than half a serving a day almost doubled their risk of diabetes. While part of this was due to weight gain associated with higher meat consumption, increased red meat consumption also independently increased the risk of having diabetes. Reducing meat consumption by a half serving a day reduced the risk of type 2 diabetes somewhat. This study did not look at vegetarians; other studies have found a lower risk of type 2 diabetes in vegetarians.
Pan A, Sun Q, Bernstein AM, Manson JE, Willett WC, Hu FB. 2013. Changes in red meat consumption and subsequent risk of type 2 diabetes mellitus: three cohorts of US men and women. JAMA Intern Med 173:1328-35.
Restaurant Meals Can Provide Calorie Overload
Many people eat out – whether for a special occasion or due to no time to cook. The average U.S. adult eats almost 5 meals a week in a restaurant. It's almost impossible for customers to know how many calories are in their meals. Even when regulations go into effect requiring large chains to post calorie information, about half of restaurants will be exempt from these requirements. Researchers recently measured the calories in the 42 most frequently purchased meals from Mexican, American, Chinese, Italian, Japanese, Thai, Indian, Greek, and Vietnamese restaurants. Meals averaged 1327 calories, more than twice what most people need at a meal. Meals from Italian restaurants had the most calories and meals from Vietnamese restaurants had the least. Meals which appeared to be meatless (bean burritos, eggplant parmesan, vegetable tempura, vegetable red curry, and Greek salad) ranged between 872 and 1948 calories. The researchers recommend that all restaurants be required to post calorie information so that consumers can make informed choices.
Urban LE, Lichtenstein AH, Gary CE, et al. 2013. The energy content of restaurant foods without stated calorie information. JAMA Intern Med 173:1292-9.
New Results from the Adventist Health Study-2
A large study of Seventh-day Adventists is currently going on. The study includes more than 70,000 adult participants whose diets range from vegan to non-vegetarian. Study subjects have been followed for close to 6 years; over that time, 2570 people died. Researchers compared the dietary patterns of those who died to those who didn't. "Vegetarians" (described as those eating meat or fish less than once a week) had a lower risk of death than "non-vegetarians" who ate meat or fish more often. While these results made headlines in the popular press, they tell us little about mortality in vegetarians who never eat meat or fish. Looking at sub-groups of vegetarians provides some more information. "Vegans" (consumed any animal product less than once a month), "lacto-ovo vegetarians" (consumed eggs or dairy at least once a month, other animal products less than once a month), and "pesco-vegetarians" (fish at least once a month, meat less than once a month) had a lower risk of death than did non-vegetarians. These results suggest that a reduction in animal product consumption is associated with lower mortality.
Orlich MJ, Singh PN, Sabaté J, et al. 2013. Vegetarian dietary patterns and mortality in Adventist Health Study 2. JAMA Intern Med 173:1230-8.
Prostate Cancer: Can Dietary Changes Affect Survival?
Other than skin cancer, prostate cancer is the most common cancer in men in the U.S.; one out of every six men will receive a prostate cancer diagnosis. Prostate cancer is the second leading cause of cancer-related deaths in men in the U.S. Most men who are diagnosed with prostate cancer do not die from it. Recent research suggests that diet may play a role in prostate cancer outcome. About 4500 men with prostate cancer were studied for a number of years. During that time, 315 men died from the disease. Men whose diets were higher in vegetable fats (mainly oils and nuts) and lower in carbohydrates had a lower risk of dying from prostate cancer and had lower death rates overall. Other studies have suggested that excessive use of refined carbohydrates may be associated with prostate cancer. It's not clear whether it is higher vegetable fat intakes or lower refined carbohydrate intakes that could explain the lower risk of death from prostate cancer seen in men with higher vegetable fat intakes. Replacing animal fats with vegetable fats also reduced the risk of death from prostate cancer. Men whose diets were higher in saturated fats and trans fats after their diagnosis of prostate cancer had a higher risk of death from all causes.
Richman EL, Kenfield SA, Chavarro JE, et al. 2013. Fat intake after diagnosis and risk of lethal prostate cancer and all-cause mortality. JAMA Intern Med 173:1318-26.
Freedland SJ. 2013. Dietary fat and reduced prostate cancer mortality: does the type of fat matter? JAMA Intern Med 173:1326-7.
Botulism Linked to Home-Fermented Tofu
The process of making fermented tofu at home involves allowing unrefrigerated tofu to be exposed to bacteria in the air for a week or more so that it ferments. Salt and spices are then added and the tofu is refrigerated. A recent report from the Centers for Disease Control and Prevention (CDC) linked botulism to home-fermented tofu. Foodborne botulism is caused by eating foods contaminated with botulinum toxin produced by the bacterium Clostridium botulinum. It can be fatal. Both of the people who developed botulism had purchased fresh tofu from the same Chinese grocery in Queens, New York, where tofu was sold in unrefrigerated, uncovered, water-filled bins. Contamination with botulinum spores may have occurred at the factory where the tofu was made or at the grocery. Tofu fermentation took place under low-acid and low-salt conditions which could have allowed spores to germinate and form toxins. The people who became ill developed severe symptoms including vomiting and difficulty breathing and were hospitalized and intubated. Both recovered from their serious illness. Although fermented tofu has only been associated with botulism once before in the U.S., in China, fermented tofu and other fermented products are responsible for most food-related botulism.
Centers for Disease Control and Prevention (CDC). 2013. Botulism associated with home-fermented tofu in two Chinese immigrants - New York City, March-April 2012. MMWR Morb Mortal Wkly Rep 62:529-32.
Researchers Question Recommendations for Cow's Milk
David Ludwig, MD, PhD and Walter Willett, MD, DrPH are physician-researchers affiliated with the Harvard Medical School. They recently published an opinion piece in a scientific journal questioning the recommendation that people in most age groups drink 3 cups of reduced-fat cow's milk daily. They point out that there is little evidence that replacing whole milk with reduced-fat milk helps people to lose weight. People tend to compensate for the lower calories in low-fat milk by eating more of other foods, often sugary snacks such as cookies. In order to reduce saturated fat, they recommend replacing whole milk with foods containing unsaturated fat or minimally processed grains, beans, fruits, and vegetables. They are concerned about the higher risk of prostate cancer associated with dairy product consumption.
Ludwig and Willett state, "Humans have no nutritional requirement for animal milk, an evolutionarily recent addition to diet." They also say, "For those with high-quality diets (including green leafy vegetables, legumes, nuts, seeds, and adequate protein), the nutritional benefits of high milk consumption may not outweigh the negative consequences." They suggest that recommendations should call for 0 to 2 or 3 cups of milk daily, rather than requiring that everyone drink 3 cups of cow's milk.
Ludwig DS, Willett WC. 2013. Three daily servings of reduced-fat milk: an evidence-based recommendation? JAMA Pediatr [Epub ahead of print].
