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* New Physical Activity Guidelines


* Mushrooms and Vitamin D


* Large Portions a Problem Worldwide



A low-carbohydrate diet increased energy expenditure during weight maintenance, according to results of a new research study in a group of overweight adults who recently lost 12% of their body weight. The low-carbohydrate diet helped burn more calories during the weight maintenance phase. The randomized trial followed 234 adults (aged 18-65 years) with a body mass index of 25 kg/m2 prior to weight loss. Before the 12-week run-in weight loss phase of the trial, all participants were placed on the same diet that comprised 45% carbohydrate, 30% fat, and 25% protein. After a 12% (+2%/-2%) weight loss during this period, 164 adults were then randomized to a high-, moderate-, or low-carbohydrate diet for 20 weeks:


* high-carbohydrate diet: 60% carbohydrate/20% fat/20% protein


* moderate-carbohydrate diet: 40% carbohydrate/40% fat/20% protein


* low-carbohydrate diet: 20% carbohydrate/60% fat/20% protein



Specifically looking at the total energy intake, every 10% decrease in the amount of carbohydrates that made up the person's total energy intake was tied to 52 more kcal burned each day (95% confidence interval [CI], 23-82 kcal/d). Compared with individuals placed on a high-carbohydrate diet during the weight maintenance phase, those on a low-carbohydrate diet had a 209 kcal/d (95% CI, 91-326 kcal/d) greater change in total energy expenditure. Even those on a moderate-carbohydrate diet saw a 91 kcal/d (95% CI, -29 to 210 kcal/d) greater change in total energy expenditure compared with those on a high-carbohydrate diet, the authors stated.


In a separate per-protocol analysis, which excluded 42 individuals who did not have maintenance weight loss within 2 kg (4.4 lsb) of their weight at the start of the 20-week randomization phase, similar trends were evident among each of the 3 diets. Among those on a low-carbohydrate diet, the hormones ghrelin and leptin were both significantly lower compared with those on a high-carbohydrate diet. As for individuals who fell into the highest third of insulin secretion prior to weight loss, measured 30 minutes after oral glucose, the differences between total energy expenditure were even greater between those on a low- versus high-carbohydrate diet:


* Full analysis: 308 kcal/d more expenditure for low-carbohydrate dieters (95% CI, 101-514 kcal/d)


* Per-protocol analysis: 478 kcal/d (95% CI, 232-724 kcal/d)



In terms of physical activity, the authors reported that "resting energy expenditure, total physical activity, and moderate to vigorous intensity physical activity were marginally higher in the group assigned to the low-carbohydrate diet (group differences or linear trends of borderline significance)." The study needs to be replicated, but short-term findings support a positive effect of reduced refined carbohydrates.


Source: Ebbeling C, et al. Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial. BMJ 2018; DOI: 10.1136/bmj.k4583.



Any physical activity will help, more is better, and it helps for a wider range of health outcomes than previously noted, according to the new US Department of Health and Human Services guidelines. Adults remain advised to do 150 to 300 minutes of moderate exercise or 75 to 150 minutes of vigorous exercise each week along with muscle and strength training twice per week to achieve the most benefits. However, the second edition removed the statement that only 10-minute bouts of physical activity counted toward meeting the guidelines and now say moving more frequently throughout the day helps toward meeting the recommendations. The recommendations added a target of 3 hours of physical activity per day for children aged 3 through 5 years. As before, children and adolescents aged 6 to 17 years should engage in moderate to vigorous physical activity for at least 60 minutes per day. The American Heart Association said it will adopt the guidelines as its official recommendations. The update added the following to the list of long-term health benefits:


* reduced risk of excessive weight gain for all groups


* improved cognition for youth


* reduced risk of bladder, endometrial, esophageal, kidney, stomach, and lung cancers


* reduced risk of dementia, including Alzheimer disease


* lower risk of falls and injurious falls for older adults


* reduced risk of postpartum depression



The advisory committee developed the physical activity guidelines based on the results of a systematic review assessing the science behind physical activity and health. Taking into account the consistency and quality of the data, the investigators addressed 38 questions and 104 subquestions. The US Department of Health and Human Services guidelines were based off of findings that were considered strong or moderate. The researchers also suggested that older adults do physical activity that consists of balance training, aerobic activity, and strengthening training. Women are advised to do 150 minutes of moderate aerobic activity each week during and after pregnancy.


In closing, the investigators emphasized, "Health professionals and policy makers should facilitate awareness of the guidelines and promote the health benefits of physical activity and support efforts to implement programs, practices, and policies to facilitate increased physical activity and to improve the health of the US population."


Source: Piercy K, et al. The physical activity guidelines for Americans. JAMA 2018; DOI: 10.1001/jama.2018.14854.



When commonly consumed mushroom species are exposed to a source of UV radiation, such as sunlight or a UV lamp, they can generate nutritionally relevant amounts of vitamin D. Without such exposure, they have little of the vitamin. The most common form of vitamin D in mushrooms is D2, with lesser amounts of vitamins D3 and D4, whereas vitamin D3 is the most common form in animal foods. Although the levels of vitamin D2 in UV-exposed mushrooms may decrease with storage and cooking, if they are consumed before the "best before" date, vitamin D2 level is likely to remain greater than 10 [micro]g/100 g fresh weight, which is higher than the level in most vitamin D-containing foods and similar to the daily requirement of vitamin D recommended internationally. Worldwide mushroom consumption has increased markedly in the past 4 decades, and mushrooms have the potential to be the only nonanimal, unfortified food source of vitamin D that can provide a substantial amount of vitamin D2 in a single serve. A new review examines the current information on the role of UV radiation in enhancing the concentration of vitamin D2 in mushrooms, the effects of storage and cooking on vitamin D2 content, and the bioavailability of vitamin D2 from mushrooms. Because mushrooms provide nutritionally relevant amounts of B group vitamins and of the minerals selenium, potassium, copper, and zinc, they are a nutritious, low energy-dense food. Currently, some larger commercial mushroom farms in the United States, Ireland, the Netherlands, and Australia expose fresh mushrooms to UV radiation, generating at least 10 [micro]g D2/100 g; therefore, a 100-g serving would provide 50% to 100% of the daily required vitamin D to consumers. Exposing dried mushrooms to UV-B radiation can also generate nutritionally useful amounts of vitamin D2, although this practice is not widespread to date. Further research is warranted to determine the optimal level of UV radiation required to produce a nutritionally useful amount of vitamin D2 in mushrooms, along with optimal storage conditions and cooking methods. The physiological benefits of mushroom-derived vitamin D2 compared with solar-derived vitamin D3 also require further investigation.


Source: Cardwell G, et al. A review of mushrooms as a potential source of dietary vitamin D. Nutrients 2018;10(10). pii: E1498; DOI: 10.3390/nu10101498.



A new multicountry study finds that large, high-calorie portion sizes in fast-food and full-service restaurants is not a problem unique to the United States. An international team of researchers found that 94% of full-service meals and 72% of fast-food meals studied in 5 countries contained 600 calories or more. The study also found that meals from fast-food restaurants contained 33% fewer calories than meals from full-service restaurants, suggesting fast food restaurants should not be singled out when exploring ways to address overeating and the global obesity epidemic. The study measured the calorie content of the most frequently ordered meals from 111 randomly selected full-service and fast-food restaurants in 5 countries-Brazil, China, Finland, Ghana, and India-plus 5 worksite canteens in Finland where worksite canteens are common and often offer subsidized lunch options to support employee health. The data were compared with comparable existing information for US restaurants.


Of note:


* When compared to the data for the United States, the mean restaurant calorie count was lower only in China, 719 versus 1088 calories/meal.


* On average, fast-food meals contained fewer calories than full-service meals, 809 versus 1317 calories/meal.


* The worksite canteens in Finland provided 25% fewer calories than the full-service and fast-food restaurants sampled in the country, 880 versus 1166 calories/meal.


* In all, 94% of meals from full-service restaurants and 72% of fast-food meals across all countries studied contained 600 calories or more. Three percent of meals from full-service restaurants in 4 countries contained 2000 calories or more.



Meals from Brazil, China, Ghana, Finland, and India were collected and analyzed between 2014 and 2017. Meal components were analyzed by bomb calorimetry. Limitations of the study include limiting samples to entrees and not the beverages, appetizers, and desserts that can be consumed with meals prepared away from home, which means that the measurements likely underestimate how large restaurant meals are. Most of the reference US data were collected more than 3 years before the data for other countries. The researchers also assumed that the size of meals ordered and collected was the same as those supplied to diners inside the restaurants, and samples were collected in a single urban center within each country. So travelers beware! Eating out has its perils to waistlines in many countries!


Source: Roberts SB, et al. Measured energy content of frequently purchased restaurant meals: multi-country cross sectional study. BMJ 2018; DOI: 10.1136/bmj.k4864.