Thursday, March 24, 2011

Warmer Weather May Be Linked to Worsened Heart Health

Marvellous the speculations that the hearts of a group of elderly Bostonians can inspire! If this were serious science, the authors below would go to places where it really is hot for their data -- but it's no great mystery why they don't. I grew up in such a hot place (tropical Far North Queensland in Australia) and I can assure everyone that we don't die of heart attacks in our youth there. And there have been some very good lifespans among my older relatives. I even have a living nonagenarian aunt. Generations of my family have lived there and we would certainly know if we were living in an unhealthy place.

Note that the population in Far North Queensland originates mainly from the British Isles so public health measures (clean water etc.) are similar to those found throughout the developed world. We are a rather good control group for assessing the effects of warm climate per se

Rising temperatures and pollution levels may act together to worsen heart health, a new study suggests.

The results show high temperatures in the summer months in a U.S. city are associated with a decrease in heart-rate variability, or how regular the time between heartbeats is, which acts as a measure of how well the heart is working. Previous studies have linked low heart-rate variability to an increased risk of death following a heart attack.

Temperature was more likely to affect cardiovascular function when ozone levels were high, the researchers say.

The findings are particularly concerning in light of the changes global warming is predicted to bring.

"Given that global warming is likely to increase both heat waves and ozone formation, such an interaction may be important for public health," said study researcher Cizao Ren, of the Harvard School of Public Health. (While ozone in the upper atmosphere protects Earth from the sun's harmful ultraviolet radiation, in the lower atmosphere it's a primary component of smog and acts as a lung irritant.)

The study involved 694 elderly men (average age 73 years) who lived in Boston. Participants had their heart-rate variability measured at least once between November 2000 and December 2008. The researchers also analyzed temperature and air pollution data from the surrounding area up to 20 days prior to the participants' examinations.

The researchers found an association between temperature and heart-rate variability in the warm season, but not the colder months. One reason for this may be that people tend to stay indoors in the winter months, where the temperature is often controlled with heating.

Previous studies have found higher temperatures can increase the risk of death from cardiovascular disease, and this effect is exacerbated by air pollution. But the new study suggests what might be happening on a biological level to cause problems.

Air temperature and ozone may influence the way the automatic nervous system functions. The automatic nervous system is a part of the central nervous system that helps the body adapt to its environment, according to the American Heart Association. It regulates body functions, including the heart's electrical activity and airflow into the lungs. Heart-rate variability is an indicator of automatic nervous system function, Ren said.

Air pollution may cause problems with reflexes in the airways to the lungs. In addition, higher temperatures may make the body more sensitive to toxins, such as ozone.

The researchers note the study involved elderly men in one part of the United States, and the findings may not be representative of the population as a whole.

The study was published in the March 8 issue of the American Journal of Epidemiology.


Obsessive 'healthy' eaters risking their lives with eating disorder orthorexia

Food faddists are hurting people -- with their various false gospels

Extreme diets and fitness regimes are putting one in ten women at risk of malnutrition and even death, experts have warned. The obsessive behaviour, which has been given the name orthorexia nervosa, is an eating disorder that has only recently been identified. It also affects one in 20 men.

Sufferers typically cut out entire food groups – often in the mistaken belief they are unhealthy or their bodies are intolerant to them – thereby depriving themselves of essential nutrition and vitamins. At the same time many over-exercise, leaving themselves weak or even emaciated.

Orthorexia has become increasingly common among women in their 30s. Many start off following celebrity fad diets such as the maple syrup detox diet, used by Naomi Campbell and Beyonce.

Cheryl Cole has championed the blood group diet, whose supporters believe different blood groups affect the body’s ability to break down certain foods.

Experts warned sticking to rigid rules was not just putting health at risk but can put a strain on relationships as people avoid eating at friends’ houses or restaurants.

The key difference between orthorexia and other common eating disorders such as anorexia nervosa or bulimia is that sufferers do not necessarily set out to lose weight but end up doing so because of a misguided belief that they are leading healthier lifestyles. Those most at risk are teenagers who are under pressure from unrealistic role models and exposed to advertisements for healthy eating and diets.

The National Centre for Eating Disorders said it had received 6,000 calls about orthorexia over the past year. It has not collated figures previously but said this represented a ‘concerning rise’ in the number of inquiries.

NCFED psychologist Deanne Jade’s estimate that one in ten women is affected by the disorder is based on her own findings over a career lasting 30 years. No official figures have been collated yet as it is only in recent years that orthorexia has been identified as a health concern. She said: ‘Orthorexia is a hidden disorder which is disguised by the healthy eating tag. ‘I am recognising it in more people year on year... in the community generally and among the people who come to see me.

‘Often people who take an interest in being healthy become overwhelmed by the conflicting information. People start cutting out food groups, like meat, and become convinced they are “intolerant” to other food groups, like wheat and dairy, so they cut those out too. ‘It is rising among young people because they are impressionable to what they read in magazines and what they see on TV.’

The term ‘orthorexia’ was coined in 1997 by Californian doctor Steven Bratman, who combined the Greek ‘orthos’, meaning ‘correct or right’, with ‘orexis’ – appetite.

Removing dairy products from the diet can lead to a deficiency in calcium, which is needed for strong bones and teeth as well as the proper function of muscles and the nervous system.

Avoiding meat deprives the body of an important source of protein and iron. Protein contains amino acids, the body’s building blocks, which help cells to grow and repair. Lack of iron causes anaemia, lack of energy, breathlessness and poor concentration.

Glenys Jones, of the Medical Research Council’s Human Nutrition Research Centre, said concerns about certain foods were fuelling the problem. ‘If there is anything negative about a food they will cut it out forever,’ she added. ‘I saw a person who cut out broccoli because she had seen an article saying she could get a disease from it.’


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