Obesity can 'lead to lack of vitamin D'

Obesity can lower vitamin D levels in the body, a study suggests.

The report, in the journal PLOS Medicine, analysed genetic data from 21 studies - a total of 42,000 people.

It found every 10% rise in body mass index (BMI) - used as an indicator of body fat - led to a 4% drop of available vitamin D in the body.

As vitamin D is stored in fatty tissue, the authors suggest the larger storage capacity in obese people may prevent it from circulating in the bloodstream.

BMI it is calculated by taking weight (in kilograms) and dividing it by height (in metres) squared. Those with a BMI of 30 or above are considered obese.

Lead author Dr Elina Hypponen, from the University College London Institute of Child Health, said the study "highlights the importance of monitoring and treating vitamin D deficiency in people who are overweight or obese".

Vitamin D is made in the skin after sun exposure and can be taken in dietary supplements.

Healthy levels are about 50 nanomole per litre - less than 30 nanomole per litre can cause the softening and weakening of bones, leading to rickets in children and osteomalacia in adults.

Prof David Haslam, from the National Obesity Forum, said: "Food intake and genetics all play a part in obesity - but this research is a reminder that physical activity, like walking the dog or going for a run out in the sunshine, shouldn't be forgotten and can help correct both weight and lack of vitamin D."

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Traffic fumes linked to lower birth weight

Pregnant women who live in areas with significant air pollution risk having babies of low birth weight, the largest study to date suggests.

The study, in Environmental Health Perspectives, looked at more than three million births in nine nations.

The effect was small and individuals should not be alarmed, but there was a notable impact on the population as a whole, the researchers said.

Low birth weight babies have a higher risk of health problems and death.

The majority survive but have an increased risk of developing conditions such as diabetes and heart disease as adults.

The International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO), by Prof Tracey Woodruff and colleagues at the University California, San Francisco, focused on airborne particulate matter small enough to penetrate the human respiratory tract.

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While the average effect on each baby is small and so should not alarm individual prospective parents, for the whole population these small risks add up across millions of people”

Dr Tony FletcherLondon School of Hygiene and Tropical Medicine

The findings indicated the relationship between birth weight and pollution was dose related - the higher the exposure, the lower the average birth weight.

Prof Woodruff said: "What's significant is that these are air pollution levels to which practically everyone in the world is commonly exposed."

Prof Kevin McConway, a statistician at the Open University said, based on the findings, if Newcastle were to halve its current particulate air pollution level it would lead to two or three fewer low weight babies out of the total 3,500 or so born in the city each year.

He said: "That sort of reduction might well be worth having, but it's not something that pregnant mothers should lose sleep over, I'd say."

Dr Tony Fletcher, senior lecturer in Environmental Epidemiology at the London School of Hygiene and Tropical Medicine, said: "The study is of excellent quality and the conclusions are clear. While the average effect on each baby is small and so should not alarm individual prospective parents, for the whole population these small risks add up across millions of people."

The Department of Environment, Food and Rural Affairs said even though air quality in the UK is "generally good, more needs to be done, especially in the cities, to reduce the harmful effects of air pollution".

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Swine flu infected

At least 20% of people, including half of schoolchildren, were infected with swine flu during the first year of the pandemic in 2009, according to data from 19 countries.

It is thought the virus killed 200,000 people around the world.

A World Health Organization-led study looked for evidence of the body's immune system fighting the virus.

It showed large numbers of people had been infected, although not all would have developed full-blown flu.

The H1N1 virus first appeared in Mexico in 2009 and rapidly spread around the world.

Anti-bodies

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What is a virus?

• Virus particles - known as virions - are tiny particles responsible for viral infection
• Typically 100 times smaller than human cells
• Viruses present wherever there are cells to infect and are most common biological entities on earth
• Influenza kills a very small proportion of those it infects but viruses such as HIV, polio and smallpox (now eradicated) can be more deadly

• Why are viruses so hard to beat?

An international group of researchers looked at more than 90,000 blood samples before and during the pandemic in countries including India, Australia and the UK.

They looked for antibodies which are produced when the body is infected with H1N1.

By comparing the figures before and during the pandemic, the researchers can determine how many people were infected as the virus spread around the world.

Approximately 24% of people had been infected overall, but half of school-age children showed signs of infection.

One of the researchers, Dr Maria Van Kerkhove from Imperial College London, said fewer than two in every 10,000 people infected died during the pandemic.

"However, those that did die are much younger than in seasonal flu so the years of life lost will be much more," she told the BBC.

"The figures drive home how incredibly infectious the virus is," she said.

Many older people, who typically die during outbreaks of flu, were protected as they had been exposed to the virus decades before.

Prof John Oxford, a virology expert at Queen Mary, University of London, said the figures "make sense".

"It was the busiest virus on the block and it displaced other influenza viruses - it was the only virus in town."

He said a similar pattern would be expected in other countries which were not analysed in the study.

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Long-term aspirin 'blindness

People who regularly take aspirin for many years, such as those with heart problems, are more likely to develop a form of blindness, researchers say.

A study on 2,389 people, in the journal JAMA Internal Medicine, showed aspirin takers had twice the risk of "wet" age-related macular degeneration.

The disease damages the 'sweet spot' in the retina, obscuring details in the centre of a patient's field of vision.

The researchers said there was not yet enough evidence to change aspirin use.

Taking low doses of aspirin every day does reduce the risk of a stroke or heart attack in patients with cardiovascular disease. There are even suggestions itcould prevent cancer.

One in 10 people in the study, conducted at the University of Sydney, were taking aspirin at least once a week. On average the participants were in their mid-60s.

Eye tests were performed after five, 10 and 15 years.

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The evidence is now accumulating about the association of aspirin and wet AMD, however, it is not overwhelming at this point”

Macular Society

By the end of the study, the researchers showed that 9.3% of patients taking aspirin developed wet age-related macular degeneration (AMD) compared with 3.7% of patients who did not take aspirin.

Their report said: "The increased risk of [wet] AMD was detected only after 10 or 15 years, suggesting that cumulative dosing is important.

"Given the widespread use of aspirin, any increased risk of disabling conditions will be significant and affect many people."

Wet AMD is caused by blood vessels growing in the wrong place. They cause swelling and bleeding which damages the retina.

The process can happen very quickly with vision being damaged in days. Age, smoking and a family history are the main risk factors.

High-risk

There are already known risks of aspirin such as causing internal bleeding. The research team suggest the risk of damaging eyesight "may also need to be considered".

They acknowledge that for most patients there is "insufficient evidence" to change how aspirin is prescribed.

However, they suggested using the drug may need to be reappraised in high-risk patients such as those with wet AMD in one eye already.

Prof Jie Jin Wang, an expert in vision research at Sydney University in Australia, said this was something doctors might want to discuss with high-risk patients.

The Macular Society said: "The evidence is now accumulating about the association of aspirin and wet AMD, however, it is not overwhelming at this point.

"For patients at risk of cardio-vascular disease, the health risks of stopping or not prescribing aspirin are much higher than those of developing wet AMD.

"Patients who are taking aspirin because their doctor has prescribed it should not stop taking it without consulting their doctor first."

Matthew Athey, from the RNIB charity, said any concerns should be discussed with a family doctor.

"However, this is interesting research as age-related macular degeneration (AMD) is the leading cause of sight loss in the UK, and this study could contribute to our understanding about why some people may develop 'wet' type macular degeneration.

"Further research is needed to clarify and investigate some of the issues raised in the study, however this association may be valuable for doctors in the future when considering aspirin for their patients."

READMORE:http://www.bbc.co.uk/news/health-21120025