Exercise Does a Body – and a Mind – Good

We’ve heard it time and time again: exercise is good for us. And it’s not just good for physical health – research shows that daily physical activity can also boost our mental health. But what actually accounts for the association between exercise and mental health?

A new article in Clinical Psychological Science, a journal of the Association for Psychological Science, explores whether certain psychosocial factors may help to explain the benefits of daily physical activity for adolescents’ mental health.

Karin Monshouwer of the Trimbos Institute in the Netherlands and colleagues at Trimbos and VU University Medical Center specifically wanted to examine two existing explanations for the link between exercise and mental health. The self-image hypothesis suggests that physical activity has positive effects on body weight and body structure, leading to positive feedback from peers and improved self-image, and ultimately improving mental health. The social interaction hypothesis, on the other hand, holds that it’s the social aspects of physical activity – such as social relationships and mutual support among team members – that contribute to the positive effects of exercise on mental health.

Monshouwer and her colleagues surveyed over 7000 Dutch students, ages 11 to 16. The adolescents completed validated surveys aimed at assessing their physical activity, mental health problems, body weight perception, and participation in organized sports. The researchers also gathered data on the adolescents’ age, gender, and socioeconomic status; whether they lived at home with their parents; and whether they lived in an urban area.

The researchers found that adolescents who were physically inactive or who perceived their bodies as either “too fat” or “too thin” were at greater risk for both internalizing problems (e.g., depression, anxiety) and externalizing problems (e.g., aggression, substance abuse). Adolescents who participated in organized sports, on the other hand, were at lower risk for mental health problems.

Confirming both the self-image hypothesis and the social interaction hypothesis, adolescents’ body weight perception (i.e., “too heavy,” “good,” or “too thin”) and sports club membership each partially accounted for the relationship between physical activity and mental health, even after taking adolescents’ backgrounds into account.

These results suggest that certain psychosocial factors – body image and social interaction – may help to explain at least part of the connection between physical activity and mental health. The researchers acknowledge, however, that other factors, such as the physiological effects of exercise, are probably also at work.

“We think that these findings are important for policymakers and anyone who works in healthcare or prevention. Our findings indicate that physical activity may be one effective tool for the prevention of mental health problems in adolescence,” says Monshouwer.

Monshouwer and her colleagues hope that future studies will be able to examine similar questions while following participants over time. Such longitudinal studies could help researchers to understand how physical activity type and context might influence the relationship between exercise and mental health.

Eating fish may reduce the risk of heart attack, but watch out for mercury

Eating fish may reduce the risk of heart attack, but it is important to steer clear from the type of fish that contains the most amounts of mercury, according to experts from Umeå University in Sweden.

The researchers have worked together with teams from Finland and other countries in order to assess whether the advantages of heathy fatty acids outweigh the risks of mercury proportion.

Previous research has said that individuals who consume fish have a decreased risk of heart disease, compared to those who eat none or very little. However, certain types of fish carry pollutants from the environment, which can be detrimental to the health of humans.

Methyl mercury, which can be found in many types of fish, may actually raise the risk of cardiovascular disease. Therefore, consuming fish with a lot of mercury, or with ample amounts of pollutants, can severely increase the risk of heart problems. However, if people are too health conscious of fish, they increase their risk of the disease because they are not receiving the benefits of healthy fish.

A recent study said that tuna, which has high levels of mercury, should be given to children less often.

The current research, which will be published in the October 2012 issue of American Journal of Clinical Nutrition (AJCN), was carried out with the intention of finding a middle point between not eating any fish and eating too much, or types that are unhealthy.

The authors analyzed why heart attack risk is linked to the amount of mercury and omega-3 fats in the body due to fish consumption. They did so by measuring hair and blood samples of volunteers who had been involved in other trials in eastern Finland and northern Sweden. The blood samples of the Swedes were taken from the Medical Biobank in Umeå. Researchers compared blood from the patients who had suffered a heart attack after their check-up appointments and those who remained in good health with no heart attacks.

They found that while mercury content increased the chance of heart attack, omega-3 fatty acids decreased the risk. The researchers noted that higher risk of heart attack due to mercury consumption was only prevalent when there was a large amount of pollutants found in the body. If there was a high level of omega-3 fatty acids, the risk was low.

The findings suggest that it is important and beneficial to reach an equilibrium between healthy and unhealthy content found in fish. In this particular study, the environmental pollutant used was mercury. However, in regards to organic pollutants, such as dioxin and PCD, the results are the same. The authors note, though, that there has been no trial done thus far concerning these substances.

According to the Swedish National Food Agency, 2-3 servings of fish should be consumed per week. However, Swedes tend to eat predatory fish, which have a high amount of mercury and should not be eaten on a regular basis. In addition, a study conducted by the National Food Agency revealed that 7 out of 10 people in Sweden do not eat enough fish.

A 2011 study said that people who eat fish on a regular basis have lower blood glucose concentrations, and a lower risk of cardiovascular disease and type 2 diabetes. The researchers conclude that it is safe, as well as beneficial, to eat fish, but staying away from fish with high levels of pollutants is important in avoiding health problems.

Eunuchs outlive other men

Castrated men living in Korea centuries ago outlived other men by a significant margin. The findings, reported in the September 25 issue of Current Biology, a Cell Press publication, suggest that male sex hormones are responsible for shortening the lives of men, the researchers say.

The evidence comes after careful study of genealogy records of noble members of the Imperial court of the Korean Chosun dynasty (AD 1392-1910).

"This discovery adds an important clue for understanding why there is a difference in the expected life span between men and women," said Kyung-Jin Min of Inha University.

The castrated boys in Korea lost their reproductive organs in accidents—usually after being bitten by dogs—or underwent castration purposefully to gain early access to the palace. Eunuchs were allowed to marry and had families by adopting castrated boys or normal girls.

People in those days kept careful genealogy records as proof that they were of the noble class. By poring over those records, Min and colleague Cheol-Koo Lee of Korea University found that eunuchs lived 14 to 19 years longer than other men did. Amongst the 81 eunuchs they studied, three lived to the ripe old age of 100 or more, a feat of longevity that remains relatively rare even in developed countries today.

The incidence of centenarians among Korean eunuchs is at least 130 times greater than it is in the developed countries, Lee notes, and that can't be explained simply by the benefits of life in the palace, either. Most eunuchs spent as much time outside the palace as they did inside it. And, in fact, kings and male members of the royal family had the shortest lives of all, typically surviving only to their mid-forties.

The findings may offer some clues to life extension and, in the meantime, men might take heed, Min and Lee quip. "For better health and longevity, stay away from stresses and learn what you can from women."

Vitamin D deficiency increases risk of heart disease

New research from the University of Copenhagen and Copenhagen University Hospital shows that low levels of vitamin D are associated with a markedly higher risk of heart attack and early death. The study involved more than 10,000 Danes and has been published in the well-reputed American journal Arteriosclerosis, Thrombosis and Vascular Biology.

Vitamin D deficiency has traditionally been linked with poor bone health. However, the results from several population studies indicate that a low level of this important vitamin may also be linked to a higher risk of ischemic heart disease, a designation that covers heart attack, coronary arteriosclerosis and angina. Other studies show that vitamin D deficiency may increase blood pressure, and it is well known that high blood pressure increases the risk of heart attack.

"We have now examined the association between a low level of vitamin D and ischemic heart disease and death in the largest study to date. We observed that low levels of vitamin D compared to optimal levels are linked to 40% higher risk of ischemic heart disease, 64% higher risk of heart attack, 57% higher risk of early death, and to no less than 81% higher risk of death from heart disease," says Dr. Peter Brøndum-Jacobsen, Clinical Biochemical Department, Copenhagen University Hospital.

The scientists have compared the 5% lowest levels of vitamin D (less than 15 nanomol vitamin per litre serum) with the 50% highest levels (more than 50 nanomol vitamin per litre serum). In Denmark, it is currently recommended to have a vitamin D status of at least 50 nanomol vitamin per litre serum.

The higher risks are visible, even after adjustment for several factors that can influence the level of vitamin D and the risk of disease and death. This is one of the methods scientists use to avoid bias.

Blood samples from more than 10,000 Danes
The population study that forms the basis for this scientific investigation is the Copenhagen City Heart Study, where levels of vitamin D were measured in blood samples from 1981-1983. Participants were then followed in the nationwide Danish registries up to the present.

"With this type of population study, we are unable to say anything definitive about a possible causal relationship. But we can ascertain that there is a strong statistical correlation between a low level of vitamin D and high risk of heart disease and early death. The explanation may be that a low level of vitamin D directly leads to heart disease and death. However, it is also possible that vitamin deficiency is a marker for poor health generally," says Børge Nordestgaard, clinical professor at the Faculty of Health and Medical Sciences, University of Copenhagen and senior physician at Copenhagen University Hospital.

Long-term goal is prevention
The scientists are now working to determine whether the connection between a low level of vitamin D and the risk of heart disease is a genuine causal relationship.

If this is the case, it will potentially have a massive influence on the health of the world population. Heart disease is the most common cause of adult death in the world according to the World Health Organization (WHO), which estimates that at least 17 million people die every year from heart disease.

"The cheapest and easiest way to get enough vitamin D is to let the sun shine on your skin at regular intervals. There is plenty of evidence that sunshine is good, but it is also important to avoid getting sunburned, which increases the risk of skin cancer. Diet with a good supply of vitamin D is also good, but it has not been proven that vitamin D as a dietary supplement prevents heart disease and death," says Børge Nordestgaard.

Diet high in total antioxidants associated with lower risk of heart attack

Coronary heart disease is a major cause of death in women. A new study has found that a diet rich in antioxidants, mainly from fruits and vegetables, can significantly reduce the risk of myocardial infarction. The study is published in the October issue of The American Journal of Medicine.

"Our study was the first to look at the effect of all dietary antioxidants in relation to myocardial infarction," says lead investigator Alicja Wolk, DrMedSci, Division of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden. "Total antioxidant capacity measures in a single value all antioxidants present in diet and the synergistic effects between them."

The study followed 32,561 Swedish women aged 49-83 from September 1997 through December 2007. The women completed a food-frequency questionnaire in which they were asked how often, on average, they consumed each type of food or beverage during the last year. The investigators calculated estimates of total antioxidant capacity from a database that measures the oxygen radical absorption capacity (ORAC) of the most common foods in the United States (no equivalent database of Swedish foods exists). The women were categorized into five groups of total antioxidant capacity of diet.

During the study, 1,114 women suffered a myocardial infarction. Women in the group with the highest total antioxidant capacity had a 20% lower risk, and they consumed almost 7 servings per day of fruit and vegetables, which was nearly 3 times more than the women with the least antioxidant capacity, who on average consumed 2.4 servings.

Dr. Wolk notes that trials testing high doses of antioxidant supplements have failed to see any benefit on coronary heart disease and, in fact, in one study higher all-cause mortality was reported. "In contrast to supplements of single antioxidants, the dietary total antioxidant capacity reflects all present antioxidants, including thousands of compounds, all of them in doses present in our usual diet, and even takes into account their synergistic effects," she explains.

In a commentary accompanying the article, Pamela Powers Hannley, MPH, Managing Editor of The American Journal of Medicine, observes that with the industrialization of our food supply, Americans began to consume more total calories and more calories from processed food high in fat and sugar. As a result, obesity rates began to climb steadily. "Although weight-loss diets abound in the US, the few which emphasize increasing intake of fruits and vegetables actually may be on the right track," she says. "Yet only 14% of American adults and 9.5% of adolescents eat five or more servings of fruits or vegetables a day."

Yogurt Fights High Blood Pressure

Adding more yogurt to your diet without increasing the number of calories you eat may help lower your risk of high blood pressure, according to new research presented at the American Heart Association's High Blood Pressure Research 2012 Scientific Sessions.

A recent study found long-term yogurt-eaters were less likely to develop high blood pressure and on average had lower systolic blood pressure than those who didn't eat yogurt. Systolic blood pressure is the top number in a blood pressure reading. It measures the force of blood against the walls of your arteries when your heart is beating.

During the 15 year study, researchers followed more than 2,000 volunteers who did not have high blood pressure at the start of the study. Yogurt consumption was measured by questionnaires filled out by the volunteers at three intervals over the study period. Study participants were 31 percent less likely to develop high blood pressure if at least 2 percent of their daily calories came from yogurt, which would be like eating at least one six-ounce cup of low-fat yogurt every three days. In addition, their systolic blood pressure increased less than that of people who didn't eat yogurt.

Exercise too much and you won't lose weight!

The amount of weight loss induced by exercise is often disappointing. A diet-induced negative energy balance triggers compensatory mechanisms, e.g., lower metabolic rate and increased appetite. However, knowledge about potential compensatory mechanisms triggered by increased aerobic exercise is limited. A randomized controlled trial was performed in healthy, sedentary, moderately overweight young men to examine the effects of increasing doses of aerobic exercise on body composition, accumulated energy balance, and the degree of compensation.

A moderate dose of exercise induced a markedly greater weight loss, than a higher dose.

No statistically significant changes were found in energy intake or nonexercise physical activity that could explain the different compensatory responses associated with 30 vs. 60 min of daily aerobic exercise. In conclusion, a similar body fat loss was obtained regardless of exercise dose.

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