Children who live in areas with air traffic pollution are threatened by higher risk of insulin resistance that can lead to diabetes in adults, a new study suggests.
According to the study on 400 participants of 10-year-olds conducted by German researchers, air pollutants are oxidizers that can impact on lipids and proteins in the blood.
To measure the participated kids’ glucose and insulin, they were asked for blood sampling.
The findings have demonstrated “insulin resistance climbed by 17 percent for every 10.6 micrograms per cubic meter increase in ambient nitrogen dioxide and by 19 percent for every 6 micrograms per cubic meter increase in particulate matter.”
Birth weight, body mass index (BMI) and exposure to second-hand smoke at home were also taken into account in the research results, according to the study report published in Diabetologia, the journal of the European Association for the Study of Diabetes.
“Exposure to fine pollution particles that invade the breathing system and get into the heart and blood vessels increases inflammation, which may be linked to insulin resistance,” clarified one of the study authors Joachim Heinrich of the German Research Center for Environmental Health.
Some experts believe that a larger study is required to confirm the possible link between air pollution and insulin resistance.
In the recent study “the measurements of blood insulin levels and estimates of pollution were taken at different times, so the findings should be regarded with caution,” said Jon Ayres, a professor of environmental and respiratory medicine at the University of Birmingham in England.
Being overweight can extend life rather than shorten it, according to a major new study that runs counter to widespread medical assumptions and years of warnings about the fatal implications of our expanding waistlines.
It sounds too good to be true, coming at the end of the season of excess, but after one of the largest reviews of research ever conducted, doctors say that carrying a few extra pounds may actually reduce the risk of premature death. Experts have repeatedly warned that obesity would soon exact a greater toll than smoking and the current generation could be the first to die before their parents.
However, the new study shows that people who are modestly overweight have a 6pc lower rate of premature death from all causes than people of ideal, “healthy” weight, while even those who are mildly obese have no increased risk. Overweight is defined as a body mass index above 25 but below 30. For a man of 5ft 9in, that is between 12 stone 4lb and 14 stone 6lb, or for a woman of 5ft 6in, it is between 11 stone 3lb and 13 stone 4lb. Ideal, healthy weight is defined as a BMI between 18.5 and 25.
Mild obesity (those with a BMI between 30 and 34.9) brings a 5pc lower premature death rate, according to the study. Although this was not statistically significant, it suggests there is no increased risk of premature death attached to that weight range.
The news will seem heaven sent to those contemplating a new year diet, and contradicts the received wisdom that being fat reduces life expectancy. It is the second time that research studies led by Katherine Flegal, a distinguished epidemiologist from the National Centre for Health Statistics at the Centres for Disease Control and Prevention in Maryland, US, have studied the link between obesity and mortality.
In 2007 the same group caused consternation among public health professionals when they published the results of a similar analysis that also showed being fat does not shorten life. Walter Willett, professor of nutrition at Harvard School of Public Health, dismissed the finding as “rubbish”.
Dr Flegal decided to conduct a second, larger, study on the same theme to counter the sceptics. She and her team examined results from 100 studies from around the world, involving three million people and 270,000 deaths.
The results are published in the respected Journal of the American Medical Association, which also published the earlier study. They show only the severely obese, with a body mass index above 35, have a significantly increased mortality, up by 29pc. Otherwise, extra weight appears to be protective. Underweight people, meanwhile, have a 10pc higher rate of premature death than those of normal size, according to earlier research. “There is already a lot of literature showing that overweight is linked with lower mortality,” said Dr Flegal. “It is not an unusual finding. But authors tend to shy away from it. They tend to underplay it or try to explain it away.”
There were warnings today that the research should not be taken to mean that there were no negative health implications associated with being overweight or obese. Tam Fry, spokesman for the UK National Obesity Forum, said: “Katherine Flegal is an extremely good researcher and I would respect her. But I am flabbergasted. The sum total of medical expert opinion cannot have got it so wrong. The consequences of people taking this research and deciding ‘let’s eat and be merry’ will be catastrophic. Mortality [the death rate] is one thing but morbidity [the disease rate] is another. If people read this and decide they are not going to die [from overeating] they may find themselves lifelong dependents on medical treatment for problems affecting the heart, liver, kidney and pancreas – to name only a few.”
Dr Flegal herself stressed that findings are not a licence to eat cream cakes. “We were only looking at mortality – not health. We are absolutely not recommending people overeat. We intended our research to give a little perspective – to counter the view that if you weigh a bit less you will live forever or if you weigh more you are doomed. The relationship between fat and mortality is more complicated than we tend to think.”
Possible explanations for the findings are that fat – adipose tissue – may protect the heart, carrying a few extra pounds may help individuals withstand periods of illness or hospitalisation when they lose appetite, and the distribution of fat on the body is more important than the amount, with extra on the hips being good while extra on the stomach is thought bad.
It may also be that the health risks of being overweight are declining with advances in medicine. Drug treatments to lower blood pressure and cholesterol have contributed to a dramatic fall in heart disease deaths. Fitness, too, may be more important than fatness. People who are overweight, smoke, eat junk food and take no exercise are heading for an early grave.
A voluptuous history: Fat through the ages
Until abundant food and sedentary lives combined to form mass obesity, plumpness was often coveted, flaunted as an indicator of health and wealth.
To stone-age man, the Venus of Willendorf – a voluptuous sculpture with enormous breasts and a bulbous belly – was worthy of celebration. Today, she would probably be put on a weight-loss programme.
Famously, Rubens, the 16th-century Flemish painter, preferred the fuller figure, depicting fleshy, large-bottomed women as the life-giving goddesses of beauty, sexuality and fertility in The Three Graces (1635).
Though portliness could be bad when it demonstrated other vices (cartoonists decided that George IV’s extravagance was most easily shown in his girth), generally, the modern-age dislikes fat. The fashion industry sells its garments on skinny models: in 2009, Kate Moss was estimated to have a BMI of 16.
Yet not all societies, even now, accept this. Samoans, Puerto Ricans and Tanzanians still celebrate largeness and six out of 10 black South Africans are clinically obese. Even in Western societies, there are differences. In a survey by Northwestern University Medical School, Chicago, white women were found to worry about their weight when their BMI hit 25, black women when it nudged 30.
With obesity straining health services, “fat phobia” is on the rise. A third of US doctors thought obese patients weak-willed, sloppy and lazy. This latest study suggest that we may need to take a broader view.
– Jeremy Laurance
Smoking “rots” the brain leading to accelerated mental decline, according to new research.
Tests of memory, planning and overall mental ability were carried out after four and eight years.
The study showed that smoking consistently reduced all three performance measures after four years.
High blood pressure and high risk of stroke were associated with lower scores for memory and overall mental ability after eight years. Being overweight was linked to poor memory.
The findings appear in the journal Age and Ageing.
They indicate that future trials should focus on combinations of risk factors rather than individual causes of mental decline, say the researchers.
Lead scientist Dr Alex Dregan, from King’s College London, said: “Cognitive decline becomes more common with ageing and for an increasing number of people interferes with daily functioning and well-being.
“Some older people can become forgetful, have trouble remembering common words or have problems organising daily tasks more than others.
“We have identified a number of risk factors which could be associated with accelerated cognitive decline, all of which, could be modifiable. This offers valuable knowledge for future prevention and treatment interventions.”
The results indicate that high blood pressure has a gradual effect on the brain over a long period, according to the scientists.
This could explain why short-term trials of blood pressure lowering drugs being used to treat mental decline had failed to show a clear benefit.
Dr Dregan added: “Our research suggests that the most promising approach to delaying or preventing early ageing of the brain is one that acknowledges the multi-causality of cognitive decline.”
Jessica Smith, from the Alzheimer’s Society, said: “We all know smoking, a high blood pressure, high cholesterol levels and a high BMI (body mass index) is bad for our heart. This research adds to the huge amount of evidence that also suggests they can be bad for our head too.
“One in three people over 65 will develop dementia but there are things people can do to reduce their risk. Eating a balanced diet, maintaining a healthy weight, exercising regularly, getting your blood pressure and cholesterol checked and not smoking can all make a difference.”
Dr Simon Ridley, from the charity Alzheimer’s Research UK, said: “Research has repeatedly linked smoking and high blood pressure to a greater risk of cognitive decline and dementia, and this study adds further weight to that evidence. Cognitive decline as we age can develop into dementia, and unravelling the factors that are linked to this decline could be crucial for finding ways to prevent the condition.”