Mediterranean diet linked with lower risk of heart disease among young US workers

Among a large group of Midwestern firefighters, greater adherence to Mediterranean-style diet was associated with lower risk factors for cardiovascular disease (CVD), according to a new study led by researchers from Harvard School of Public Health (HSPH) and Cambridge Health Alliance (CHA). The study is the first to assess the effects of Mediterranean-style diet among a group of young, working U.S. adults.

The study will appear online in PLOS ONE on February 4, 2014.

"Our study adds more evidence showing the health benefits of a Mediterranean diet, even after adjusting for exercise and body weight," said Stefanos Kales, associate professor in the Department of Environmental Health at HSPH and chief of occupational and environmental medicine at CHA.

U.S. firefighters are known to have a high prevalence of obesity and risk factors for CVD. A Mediterranean diet, rich in fish, nuts, vegetables, and fruits, has been shown in previous studies to lower risk of CVD. However, those studies have primarily been conducted among older people, those with existing health conditions, and among Mediterranean populations.

The researchers analyzed medical and lifestyle data, including dietary habits, from an existing cohort of 780 male firefighters in the Midwest. They developed a modified Mediterranean diet score (mMDS) to assess the participants' dietary patterns.

The firefighter group with greatest adherence to Mediterranean-style diet showed a 35% decreased risk in metabolic syndrome, a condition with risk factors that include a large waistline, high triglyceride level, low HDL ("good") cholesterol level, high blood pressure, and high blood sugar. The group with the highest mMDS also had a 43% lower risk of weight gain compared with the lowest mMDS group. Additionally, greater adherence to a Mediterranean-style diet was significantly associated with higher HDL cholesterol and lower LDL ("bad") cholesterol. Consistent with previous investigations, obese participants in the firefighter study reported a higher intake of both fast foods and sugary drinks.

The study shows that promoting Mediterranean-style diets could have significant health benefits for young, working populations. "The logical next steps from our investigation are studies using the workplace to specifically promote Mediterranean dietary habits among firefighters and other U.S. workers," said Justin Yang, lead author of the study and a post-doctoral fellow at HSPH.

Shivering and exercise may convert white fat to brown

A new study suggests that shivering and bouts of moderate exercise are equally capable of stimulating the conversion of energy-storing 'white fat' into energy-burning 'brown fat'.

Around 50 g of white fat stores more than 300 kilocalories of energy. The same amount of brown fat could burn up to 300 kilocalories a day.

Endocrinologist Dr Paul Lee, from Sydney's Garvan Institute of Medical Research, recently undertook the study at the National Institutes of Health (NIH) in Washington*, funded as an NHMRC Early Career Research Fellow.

His work uncovered a way that fat and muscle communicate with each other through specific hormones – turning white fat cells into brown fat cells to protect us against cold.

Dr Lee showed that during cold exposure and exercise, levels of the hormone irisin (produced by muscle) and FGF21 (produced by brown fat) rose. Specifically, around 10-15 minutes of shivering resulted in equivalent rises in irisin as an hour of moderate exercise. In the laboratory, irisin and FGF21 turn human white fat cells into brown fat cells over a period of six days. The study is now published in Cell Metabolism.

We are all born with supplies of brown fat around our necks, nature's way of helping to keep us warm as infants. Until only a few years ago, it was thought to vanish in early infancy, but we now know that brown fat is present in most, if not all, adults. Adults with more brown fat are slimmer than those without.

"Excitement in the brown fat field has risen significantly over last few years because its energy-burning nature makes it a potential therapeutic target against obesity and diabetes," said Dr Lee.

"White fat transformation into brown fat could protect animals against diabetes, obesity and fatty liver. Glucose levels are lower in humans with more brown fat."

In the current study, Lee set out to understand the mechanism underlying the activation of brown fat. It was already known that cold temperatures stimulate brown fat, but was unclear how the body signals that message to its cells.

The body can sense and relay environmental changes to different organs via nerves and hormones. Being an endocrinologist, Lee investigated the hormones that are stimulated by cold environments.

"When we are cold, we first activate our brown fat because it burns energy and releases heat to protect us. When that energy is insufficient, muscle contracts mechanically, or shivers, thereby generating heat. However we did not know how muscle and fat communicate in this process."

"So we exposed volunteers to increasing cold, from 18 to 12 degrees, until they shivered. We drew blood samples to measure hormone levels and detected shivering by special devices placed on the skin that sense muscle electrical activity."

"Volunteers started to shiver by around 16 or 14 degrees, varying between individuals."

"We identified two hormones that are stimulated by cold – irisin and FGF21 – released from shivering muscle and brown fat respectively. These hormones fired up the energy-burning rate of human white fat cells in the laboratory, and the treated fat cells began to emit heat – a hallmark of brown fat function."

A team from Harvard University discovered irisin through NIH-funded research in 2012, identifying it as a muscle hormone stimulated by exercise that turned white fat in animals into brown fat.

The puzzling aspect of the finding was that exercise itself produces heat, so why would exercising muscle initiate a process that would generate yet more heat?

Lee invited cold-exposure study participants to take part in exercise tests to compare the two processes. "We found that exercising for an hour on a bicycle at a moderate level produced the same amount of irisin as shivering for 10-15 minutes," he said.

"We speculate exercise could be mimicking shivering – because there is muscle contraction during both processes, and that exercise-stimulated irisin could have evolved from shivering in the cold."

"From a clinical point of view, irisin and FGF21 represent a cold-stimulated hormone system, which was previously unknown, and may be harnessed in future obesity therapeutics through brown fat activation."

Study Finds Dramatic Rise in Skin Cancer among Middle-Aged Adults

A new Mayo Clinic study found that among middle-aged men and women, 40 to 60 years old, the overall incidence of skin cancer increased nearly eightfold between 1970 and 2009, according to a study published in the January issue of Mayo Clinic Proceedings.

“The most striking finding was among women in that age group,” says dermatologist Jerry Brewer, M.D., principal investigator of the study. “Women between 40 and 50 showed the highest rates of increase we’ve seen in any group so far.”

There has been widespread concern in recent years about the rising incidence of melanoma, which affects 75,000 Americans annually and results in nearly 9,000 deaths. Few studies, however, have investigated which age brackets of adults are most at risk.

Dr. Brewer’s team conducted a population-based study using records from the Rochester Epidemiology Project, a collaboration between healthcare providers in southeastern Minnesota that allows researchers to study health and illnesses in the community. They found that among white, non-Hispanic adults in the 40 to 60 age group the incidence of skin cancer increased 4.5-fold among men and 24-fold among women.

In particular, women under 50 showed a marked increase in melanoma, a finding that may prompt future studies of a premenopausal hormonal connection to the disease. Even though women were more likely to develop melanoma, men were more likely to have deeper lesions.

Another significant finding was that the overall chances of surviving melanoma increased by 7 percent each year of the study. “The improved survival rates may be due to increased public awareness, more frequent screenings, and detection of skin cancer at earlier stages,” says Dr. Brewer. “People have more access to dermatologists than before, and we have new tools, like dermoscopy [which includes the widely used ABCDE criteria], to view details of a mole and detect earlier melanomas.”

The steepest increase in melanoma occurred in the last decade covered by the study, 2000 to 2009. The uptick, researchers speculate, may be connected to the popularization of tanning beds in the 1980s and 1990s.

“There’s been a cultural trend for many decades in which people connect being tan with being fit and even successful,” says Brewer. This trend could be one of the reasons, Dr. Brewer says, that melanoma has become so prevalent in the groups he has studied.

The current study follows on the heels of last year’s findings, in which Dr. Brewer’s team noted alarming rates of melanoma in young adults, ages 18 to 39. His group will continue to track the trend of melanoma and survival rates among adults over 60.

Skin cancer can be prevented. Dr. Brewer gives four simple ways to improve your chances of preventing skin cancer:

1. Avoid the use of tanning beds

2. Use sunscreen

3. Be familiar with your skin by performing frequent self-skin examinations

4. Check in with your dermatologist annually

Vitamin C and E supplements hampers endurance training

Vitamin C and E supplements may blunt the improvement of muscular endurance – by disrupting cellular adaptions in exercised muscles – suggests a new study published today [3 February] in The Journal of Physiology.

As vitamin C and E supplements are widely used, understanding if they interfere with cellular and physiological adaptations to exercise is of interest to people exercising for health purposes as well as to athletes.

Dr Gøran Paulsen, who led the study at the Norwegian School of Sport Sciences, explains:

"Our results show that vitamin C and E supplements blunted the endurance training-induced increase of mitochondrial proteins, which are needed to improve muscular endurance."

In the 11-week trial, 54 young, healthy men and women were randomly allocated to receive either 1000mg vitamin C and 235mg vitamin E (consistent with amounts found in shop supplements), or a placebo (a pill containing no active ingredients). Neither the subjects nor the investigators knew which participant received the vitamins or placebos.

The participants completed an endurance training programme, consisting of three to four sessions per week, of primarily running. Fitness tests, blood samples and muscle biopsies were taken before and after the intervention.

Whilst the supplements did not affect maximal oxygen uptake or the results of a 20 metre shuttle test, the results showed that markers for the production of new muscle mitochondria – the power supply for cells – increased only in the group without supplements.

The National Health Service (NHS) says taking less than 540mg vitamin E and 1000mg vitamin C supplements per day is unlikely to cause any harm.

Dr Paulsen says:

"Our results indicate that high dosages of vitamin C and E – as commonly found in supplements – should be used with caution, especially if you are undertaking endurance training."

A significant trend has been identified, but the molecular processes requires further research. Dr Paulsen says:

"Future studies are needed to determine the underlying mechanisms of these results, but we assume that the vitamins interfered with cellular signalling and blunted expression of certain genes."

Previous studies show that exercising increases muscle oxidant production, which participates in the signalling processes leading to muscle adaption. It is possible that high doses of vitamins C and E act as antioxidants and take away some of this oxidative stress, hence blocking muscular endurance development.

Consumption of added sugar = increased risk for death from cardiovascular disease

Many U.S. adults consume more added sugar (added in processing or preparing of foods, not naturally occurring as in fruits and fruit juices) than expert panels recommend for a healthy diet, and consumption of added sugar was associated with increased risk for death from cardiovascular disease (CVD), according to a study published by JAMA Internal Medicine, a JAMA Network publication.

Recommendations for added sugar consumption vary and there is no universally accepted threshold for unhealthy levels. For example, the Institute of Medicine recommends that added sugar make up less than 25 percent of total calories, the World Health Organization recommends less than 10 percent, and the American Heart Association recommends limiting added sugars to less than 100 calories daily for women and 150 calories daily for men, according to the study background.

Major sources of added sugar in Americans' diets are sugar-sweetened beverages, grain-based desserts, fruit drinks, dairy desserts and candy. A can of regular soda contains about 35g of sugar (about 140 calories).

Quanhe Yang, Ph.D., of the Centers for Disease Control and Prevention, Atlanta, and colleagues used national health survey data to examine added sugar consumption as a percentage of daily calories and to estimate association between consumption and CVD.

Study results indicate that the average percentage of daily calories from added sugar increased from 15.7 percent in 1988-1994 to 16.8 percent in 1999 to 2004 and decreased to 14.9 percent in 2005-2010.

In 2005-2010, most adults (71.4 percent) consumed 10 percent of more of their calories from added sugar and about 10 percent of adults consumed 25 percent or more of their calories from added sugar.

The authors note the risk of death from CVD increased with a higher percentage of calories from added sugar. Regular consumption of sugar-sweetened beverages (seven servings or more per week) was associated with increased risk of dying from CVD.

"Our results support current recommendations to limit the intake of calories from added sugars in U.S. diets," the authors conclude.

Commentary: New Unsweetened Truths About Sugar

In a related commentary, Laura A. Schmidt, Ph.D., M.S.W., M.P.H., of the University of California, San Francisco, writes: "We are in the midst of a paradigm shift in research on the health effects of sugar, one fueled by extremely high rates of added sugar overconsumption in the American public."

"In sum, the study by Yang et al contributes a range of new findings to the growing body of research on sugar as an independent risk factor in chronic disease. It underscores the likelihood that, at levels of consumption common among Americans, added sugar is a significant risk factor for CVD mortality above and beyond its role as empty calories leading to weight gain and obesity," Schmidt continues.

"Yang et al underscore the need for federal guidelines that help consumers set safe limits on their intake as well evidence-based regulatory strategies that discourage excess sugar consumption at the population level," the author concludes.

Perceived control reduces mortality risk at low, not high, education levels

The less education you have, the more your attitude counts when it comes to staying alive and well.

That's the finding of a new study conducted by personality researchers from the University of Rochester and Brandeis University. They found that adults without college degrees live longer if they feel like they're in control of their lives. Those who feel little control are three times as likely to die.

"Being uneducated and poor doesn't mean you're doomed, despite all of the studies showing people with less education are more likely to experience disease, disability, and premature death," says lead author Nicholas Turiano, Ph.D., a post-fellow in Psychiatry at the U of R.

The study, published by the American Psychological Association's Health Psychology journal, followed 6,135 people, ages 25 to 75, for 14 years. The respondents were part of an ongoing, national questionnaire called the National Survey of Midlife in the United States. It collects a variety of data, including an assessment of each subject's perceived ability to exert influence over life circumstances. Researchers adjusted for socioeconomic factors such as income and the education level of the subjects' parents. Turiano says that even after these other variables are taken into account, the findings held. Sense of control did not affect the mortality rate of people with higher levels of education.

Turiano cautions more research is needed to find out why or how people develop a strong sense of control, or when this development occurs. Researchers suspect numerous innate and external factors contribute to perceived control. Turiano says further study could lead to interventions that help this population feel more positive and, ultimately, live longer

Diet Beverages and Body Weight

Overweight and obese adults who drink diet beverages consume significantly more solid-food calories—particularly from snacks—than those who drink sugary beverages. The findings highlight the challenges in using diet beverages to help control weight.

Excess weight can raise your risk for type 2 and gestational diabetes, heart disease, cancer, and other health problems. But maintaining a healthy weight is difficult for many people. Body weight reflects a complicated balance between the amount of calories consumed and the amount of energy used by the body.

Diet beverage use has skyrocketed in recent decades. It’s now a common weight control strategy. It might make sense to think that diet beverages would help you lose weight due to their lack of calories. But the body’s mechanisms for maintaining weight are subtle and complex. Studies into how diet beverages affect weight control have found conflicting results.

To gain a better understanding of the relationship between diet beverage consumption and caloric intake, a research team led by Dr. Sara N. Bleich at the Johns Hopkins Bloomberg School of Public Health examined patterns of food and beverage consumption. They used data collected between 1999 and 2010 in the National Health and Nutrition Examination Survey (NHANES), a periodic survey of the health and habits of the U.S. population by the Centers for Disease Control and Prevention. The analysis was funded by NIH’s National Heart, Lung, and Blood Institute (NHLBI).

The researchers studied almost 24,000 adults, age 20 and older, who reported all the food and beverages they had consumed in a previous 24-hour period. Results appeared online in the American Journal of Public Health on January 16, 2014.

The team found that 11% of healthy-weight, 19% of overweight, and 22% of obese adults drank diet beverages. Diet drinks appeared to help healthy-weight adults maintain their weight. These adults consumed less food and significantly fewer total calories on a typical day than did healthy-weight adults who drank sugared drinks.

The total calories consumed by overweight and obese adults who drank diet beverages, however, were similar to that of those who drank sugary beverages. Heavier adults who drank diet beverages tended to eat more calories in the form of solid food. Overweight and obese adults who drank diet beverages consumed 88 and 194 more calories from solid foods per day, respectively, than those who drank sugared beverages.

To understand these differences in solid-food intake, the scientists took a closer look at patterns of solid-food consumption. Notably, obese adults who consumed diet drinks ate significantly more snacks than those who had sugared drinks. Those who drank diet beverages consumed 131 calories per day in salty snacks and 243 in sweet snacks, compared to 107 and 213, respectively, for obese adults who drank sugared drinks.

“The results of our study suggest that overweight and obese adults looking to lose or maintain their weight—who have already made the switch from sugary to diet beverages—may need to look carefully at other components of their solid-food diet, particularly sweet snacks, to potentially identify areas for modification,” Bleich says.

Controlled studies would be needed to confirm these results. Nevertheless, the research highlights the need for heavier adults who drink diet beverages to closely monitor their food intake.