Being overweight increases the chances of premature death

Global study contradicts a previous finding that being overweight increases longevity

Being overweight increases the chances of premature death, according to a USC researcher.

Although people accept that obesity can shorten a person's life span, scientists have debated whether the weight category between normal and obese is, in fact, a health risk.

Being overweight definitely does not help people live longer, said Jonathan Samet, director of the USC Institute for Global Health. His statement is backed by a four-continent effort involving 239 studies and data from 10.6 million people. The collaborative and comprehensive study -- one of the largest to date -- was published in The Lancet.

The results have important clinical and public health implications, Samet said.

"Physicians should identify being overweight as posing a risk to health," said Samet, one of the study's authors and holder of the Flora L. Thornton Chair in Preventive Medicine at the Keck School of Medicine of USC. "Increasing the risk of dying is a powerful indicator of health. The new results on overweight should be strong motivation for people to return to a healthy weight."

The World Health Organization states that more than 1.9 billion people -- about 39 percent of adults -- are overweight, defined as having a body mass index between 25 and 30. For example, a 5-foot-4 person who weighs 140 pounds has a healthy BMI of 24. Add five pounds and this individual would be considered overweight.

The study analyzed participants who had never smoked, did not have chronic disease and were still alive five years after the research began. The study involved 385,879 deaths in 239 studies.

Overweight and obesity were strongly connected to coronary heart disease, stroke and respiratory disease death, and were moderately linked to cancer mortality. The findings were reflected in Europe, North America and East Asia.

The new finding contradicts a 2013 review article

The new finding on overweight is counter to the results of a prior paper in the Journal of the American Medical Association, which found that being overweight actually adds to one's life span, and "grade 1 obesity" (BMI 30-35) did not increase mortality. The JAMA article was based on a review of 97 studies with 2.9 million participants.

The Lancet study did more than just summarize published results; the data from all 239 studies was analyzed in a standard way.

"Our study was able to reproduce [the JAMA review's] findings when conducting crude analyses with inadequate control of reverse causality, but not when we conducted appropriately strict analyses," the Lancet paper stated.

The WHO states that about 95 million children -- mostly in less developed regions -- are underweight.

Being underweight, according to the study, was associated with substantially higher respiratory disease mortality and somewhat higher death rates from coronary heart disease, stroke and cancer. These findings held true in Asia, Australia, New Zealand, Europe and North America.

Keeping your weight in check

One of the study's limitations, like many other research papers in this arena, is the use of BMI as a surrogate for visceral fat, which is thought to be key in bringing about the negative consequences linked to obesity.

"The health risk associated with obesity is thought to be driven by abdominal fat," Samet said. "BMI is an imperfect measure of fat in someone's belly. There are more gold standard ways to measure fat, but that can't be done for 10.6 billion people."

Using an accepted but imperfect measure, the study was able to find a connection between premature death and being overweight. The proportion of premature deaths that could be avoided with a healthy weight (between BMI 18.5 and 25) is about 1 in 5 in North America, 1 in 6 in Australia and New Zealand, 1 in 7 in Europe and 1 in 20 in East Asia.

In short, like smoking, the health problems associated with underweight, overweight and obesity are substantial but potentially preventable.
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Moderate physical activity linked with 50 percent reduction in cardiovascular death in over-65s

Moderate physical activity is associated with a greater than 50% reduction in cardiovascular death in over-65s, according to research presented at ESC Congress 2016 today.1 The 12 year study in nearly 2500 adults aged 65 to 74 years found that moderate physical activity reduced the risk of an acute cardiovascular event by more than 30%. High levels of physical activity led to greater risk reductions.

"The role of physical activity in preventing cardiovascular disease (CVD) in people of working age is well established," said Professor Riitta Antikainen, professor of geriatrics at the University of Oulu, Finland. "But relatively little is known about the effect of regular physical activity on CVD risk in older people."

The present study assessed the association between leisure time physical activity and CVD risk and mortality in 2456 men and women aged 65 to 74 years who were enrolled into the National FINRISK Study between 1997 and 2007.

Baseline data collection included self-administered questionnaires on physical activity and other health related behaviour, clinical measurements (blood pressure, weight and height), and laboratory measurements including serum cholesterol. Participants were followed up until the end of 2013. Deaths were recorded from the National Causes of Death Register and incident CVD events (coronary heart disease and stroke) were collected from the National Hospital Discharge register.

The researchers classified self-reported physical activity as:

• Low: reading, watching TV or working in the household without much physical activity.
• Moderate: walking, cycling or practising other forms of light exercise (fishing, gardening, hunting) at least four hours per week.
• High: recreational sports (for example running, jogging, skiing, gymnastics, swimming, ball games or heavy gardening) or intense training or sports competitions at least three hours a week.
•  

During a median follow-up of 11.8 years, 197 participants died from CVD and 416 had a first CVD event.

When the researchers assessed the link between physical activity and outcome they adjusted for other cardiovascular risk factors (blood pressure, smoking and cholesterol) and social factors (marital status and education). To minimise reverse causality, where worse health leads to less physical activity, patients with coronary heart disease, heart failure, cancer, or prior stroke at baseline were excluded from the analysis.

The investigators found that moderate and high leisure time physical activity were associated with a 31% and 45% reduced risk of an acute CVD event, respectively (figure 1). Moderate and high leisure time physical activity were associated with a 54% and 66% reduction in CVD mortality.

Professor Antikainen said: "Our study provides further evidence that older adults who are physically active have a lower risk of coronary heart disease, stroke, and death from cardiovascular disease. The protective effect of leisure time physical activity is dose dependent - in other words, the more you do, the better. Activity is protective even if you have other risk factors for cardiovascular disease such as high cholesterol."

She concluded: "Physical exercise may become more challenging with ageing. However, it is important for older people to still get enough safe physical activity to stay healthy after their transition to retirement."

Mediterranean diet associated with lower risk of death in cardiovascular disease patients

The Mediterranean diet is associated with a reduced risk of death in patients with a history of cardiovascular disease, according to results from the observational Moli-sani study presented at ESC Congress 2016 today.1

"The Mediterranean diet is widely recognised as one of the healthier nutrition habits in the world," said Professor Giovanni de Gaetano, head of the Department of Epidemiology and Prevention at the I.R.C.C.S. Neuromed Institute in Pozzilli, Italy. "In fact, many scientific studies have shown that a traditional Mediterranean lifestyle is associated with a lower risk of various chronic diseases and, more importantly, of death from any cause."

"But so far research has focused on the general population, which is mainly composed of healthy people," he added. "What happens to people who have already suffered from cardiovascular disease? Is the Mediterranean diet optimal for them too?"

The answer is yes, according to a study in patients with a history of cardiovascular disease, such as coronary artery disease and stroke. The patients were among the participants enrolled into the Moli-sani project, a prospective epidemiological study that randomly recruited around 25 000 adults living in the Italian region of Molise.2

"Among the participants, we identified 1197 people who reported a history of cardiovascular disease at the time of enrolment into Moli-sani," said Dr Marialaura Bonaccio, lead author of the research.

Food intake was recorded using the European Prospective Investigation into Cancer (EPIC) food frequency questionnaire. Adherence to the Mediterranean diet was appraised with a 9-point Mediterranean diet score (MDS). All-cause death was assessed by linkage with data from the office of vital statistics in Molise.

During a median follow up of 7.3 years there were 208 deaths. A 2-point increase in the MDS was associated with a 21% reduced risk of death after controlling for age, sex, energy intake, egg and potato intake, education, leisure-time physical activity, waist to hip ratio, smoking, hypertension, hypercholesterolaemia, diabetes and cancer at baseline.

When considered as a 3-level categorical variable, the top category (score 6-9) of adherence to the Mediterranean diet was associated with 37% lower risk of death compared to the bottom category (0-3).

Professor de Gaetano said: "We found that among those with a higher adherence to the Mediterranean diet, death from any cause was reduced by 37% in comparison to those who poorly adhered to this dietary regime."

The researchers deepened their investigation by looking at the role played by individual foods that make up Mediterranean diet. "The major contributors to mortality risk reduction were a higher consumption of vegetables, fish, fruits, nuts and monounsaturated fatty acids - that means olive oil," said Dr Bonaccio.

Professor de Gaetano concluded: "These results prompt us to investigate the mechanism(s) through which the Mediterranean diet may protect against death. This was an observational study so we cannot say that the effect is causal. We expect that dietary effects on mediators common to chronic diseases such as inflammation might result in the reduction of mortality from any cause but further research is needed."

Stopping exercise decreases brain blood flow in older adults

We all know that we can quickly lose cardiovascular endurance if we stop exercising for a few weeks, but what impact does the cessation of exercise have on our brains? New research led by University of Maryland School of Public Health researchers examined cerebral blood flow in healthy, physically fit older adults (ages 50-80 years) before and after a 10-day period during which they stopped all exercise. Using MRI brain imaging techniques, they found a significant decrease in blood flow to several brain regions, including the hippocampus, after they stopped their exercise routines.

"We know that the hippocampus plays an important role in learning and memory and is one of the first brain regions to shrink in people with Alzheimer's disease," says Dr. J. Carson Smith, associate professor of kinesiology and lead author of the study, which is published in Frontiers in Aging Neuroscience in August 2016. "In rodents, the hippocampus responds to exercise training by increasing the growth of new blood vessels and new neurons, and in older people, exercise can help protect the hippocampus from shrinking. So, it is significant that people who stopped exercising for only 10 days showed a decrease in brain blood flow in brain regions that are important for maintaining brain health."

The study participants were all "master athletes," defined as people between the ages of 50 and 80 (average age was 61) who have at least 15 years history of participating in endurance exercise and who have recently competed in an endurance event. Their exercise regimens must have entailed at least four hours of high intensity endurance training each week. On average, they were running ~36 miles (59 km) each week or the equivalent of a 10K run a day! Not surprisingly, this group had a V02 max above 90% for their age. This is a measure of the maximal rate of oxygen consumption of an individual and reflects their aerobic physical fitness.

Dr. Smith and colleagues measured the velocity of blood flow in brain with an MRI scan while they were still following their regular training routine (at peak fitness) and again after 10 days of no exercise. They found that resting cerebral blood flow significantly decreased in eight brain regions, including the areas of the left and right hippocampus and several regions known to be part of the brain's "default mode network" - a neural network known to deteriorate quickly with a diagnosis of Alzheimer's disease. This information adds to the growing scientific understanding of the impact of physical activity on cognitive health.

"We know that if you are less physically active, you are more likely to have cognitive problems and dementia as you age," says Dr. Smith. "However, we did not find any evidence that cognitive abilities worsened after stopping exercising for just 10 days. But the take home message is simple - if you do stop exercising for 10 days, just as you will quickly lose your cardiovascular fitness, you will also experience a decrease in blood brain flow."

Dr. Smith believes that this could have important implications for brain health in older adults, and points to the need for more research to understand how fast these changes occur, what the long term effects could be, and how fast they could be reversed when exercise is resumed.

Selenium status influence cancer risk

As a nutritional trace element, selenium forms an essential part of our diet. In collaboration with the International Agency for Research on Cancer, researchers from Charité - Universitätsmedizin Berlin have been able to show that high blood selenium levels are associated with a decreased risk of developing liver cancer. In addition to other risk factors, the study also examines in how far selenium levels may influence the development of other types of cancer. Results from this study have been published in the American Journal of Clinical Nutrition.

Selenium (Se) is found in foods like fish, shellfish, meat, milk and eggs; certain South American nuts, such as Brazil nuts, are also good sources of selenium. It is a trace element that occurs naturally in soil and plants, and enters the bodies of humans and animals via the food they ingest. European soil has a rather low selenium concentration, in comparison with other areas of the world, especially in comparison to North America. Deficiencies of varying degrees of severity are common among the general population, and are the reason why German livestock receive selenium supplements in their feed.

While in Europe, neither a selenium-rich diet nor adequate selenium supplementation is associated with adverse effects, selenium deficiency is identified as a risk factor for a range of diseases. "We have been able to show that selenium deficiency is a major risk factor for liver cancer," says Prof. Dr. Lutz Schomburg of the Institute of Experimental Endocrinology, adding: "According to our data, the third of the population with lowest selenium status have a five- to ten-fold increased risk of developing hepatocellular carcinoma - also known as liver cancer."

In this case-control study, the team of European researchers investigated a cohort of 477,000 participants, and selected individuals who had developed hepatocellular carcinoma during a 10-year follow up. Blood samples were also chosen from healthy participants and subsequently analyzed to determine their selenium status. "Our study does not show that selenium supplementation has a direct protective effect against liver cancer. However, it does confirm the importance of a balanced diet, of which selenium forms an integral part," explains Prof. Schomburg. Previous studies had suggested a similar relationship between a person's selenium status and their risk of developing colon cancer, as well as their risk of developing autoimmune thyroid disease.

Breast cancer mortality lower in women who breastfeed

A new study of women 20 years after undergoing surgery for primary breast cancer shows that breastfeeding for longer than 6 months is associated with a better survival rate. Among breast cancer survivors who breastfed for >6 months, both breast cancer mortality and overall mortality risk were less after 20 years, according to the study published in Breastfeeding Medicine, the official journal of the Academy of Breastfeeding Medicine published by Mary Ann Liebert, Inc., publishers. The article is available free on the Breastfeeding Medicine website until September 30, 2016.

In "Breastfeeding Associated with Reduced Mortality in Women with Breast Cancer," Margaretha Lööf-Johanson, MD, Lars Brudin, MD, PhD, and Marie Sundquist, MD, PhD, University of Linkoping, and County Hospital, Kalmar, Sweden, and Carl Edvard Rudebeck, MD, PhD, University of Tromso, Norway, examined the link between lifetime breastfeeding history and both breast cancer-specific and overall survival among women treated for breast cancer who had lived long enough for other causes of death to contribute substantially to mortality.

"This study confirms that the long-term maternal health benefits of breastfeeding are not only preventative in nature, but that it also has the capacity to reduce the severity of breast cancer," says Arthur I. Eidelman, MD, Editor-in-Chief of Breastfeeding Medicine.

Western diet increases Alzheimer's risk

Globally, about 42 million people now have dementia, with Alzheimer's disease as the most common type of dementia. Rates of Alzheimer's disease are rising worldwide. The most important risk factors seem to be linked to diet, especially the consumption of meat, sweets, and high-fat dairy products that characterize a Western Diet. For example, when Japan made the nutrition transition from the traditional Japanese diet to the Western diet, Alzheimer's disease rates rose from 1% in 1985 to 7% in 2008, with rates lagging the nutrition transition by 20-25 years. 

The evidence of these risk factors, which come from ecological and observational studies, also shows that fruits, vegetables, grains, low-fat dairy products, legumes, and fish are associated with reduced risk. "Using Multicountry Ecological and Observational Studies to Determine Dietary Risk Factors for Alzheimer's Disease," a review article from the Journal of the American College of Nutrition presents the data.

In addition to reviewing the journal literature, a new ecological study was conducted using Alzheimer's disease prevalence from 10 countries (Brazil, Chile, Cuba, Egypt, India, Mongolia, Nigeria, Republic of Korea, Sri Lanka, and the United States) along with dietary supply data 5, 10, and 15 years before the prevalence data. Dietary supply of meat or animal products (minus milk) 5 years before Alzheimer's disease prevalence had the highest correlations with Alzheimer's disease prevalence in this study. The study discussed the specific risk each country and region faces for developing Alzheimer's disease based on their associated dietary habits.

Residents of the United States seem to be at particular risk, with each person in the U.S. having about a 4% chance of developing Alzheimer's disease, likely due in part to the Western dietary pattern, which tends to include a large amount of meat consumption. The author, William B. Grant, states, "reducing meat consumption could significantly reduce the risk of Alzheimer's disease as well as of several cancers, diabetes mellitus type 2, stroke, and, likely, chronic kidney disease."

He concludes, "Mounting evidence from ecological and observational studies, as well as studies of mechanisms, indicates that the Western dietary pattern -- especially the large amount of meat in that diet -- is strongly associated with risk of developing Alzheimer's disease and several other chronic diseases. Although the traditional Mediterranean diet is associated with about half the risk for Alzheimer's disease of the Western diet, the traditional diets of countries such as India, Japan, and Nigeria, with very low meat consumption, are associated with an additional 50% reduction in risk of Alzheimer's disease."