Wednesday, June 12, 2013

Teenagers who spend time in the sun are 'significantly' less likely to develop hay fever and eczema

But why?  Maybe less healthy children to start with are kept indoors and out of the sun

Teenagers who spend more time outside in the sun have a lower risk of hay fever and eczema, according to a new study.

Those who spend more than four hours per day exposed to sunlight on summer days benefit from decreased rates of both conditions, Australian scientists found.

‘Higher sun exposure during summer holidays and summer weekends in adolescence was associated with significantly reduced eczema and rye grass positive rhinitis,’ they wrote.

The team found that the benefit of sun exposure persisted after accounting for measured levels of vitamin D, the so-called sunshine vitamin which our body produces from sunlight on our skin, in participants.

This suggests the benefit stems from another mechanism, according to the researchers led by Dr Andrew Kemp at the Royal Children’s Hospital in Melbourne.

The study involved 415 participants, who were recruited at birth and followed until the age of 16.  Their average daily duration of sun exposure in summer months was recorded at eight and 16 years of age.

At 16, researchers also recorded whether they suffered from hay fever, eczema, asthma or showed any signs of sensitisation to allergens.

There was no significant association between sun exposure aged eight and any allergic disease or allergen sensitisation at 16.

But teens who spent more than four hours per summer day in the sun aged 16 had a significantly decreased risk of hay fever and eczema.

Asthma was not related to sun exposure, whether assessed through diagnosis by a doctor or use of asthma medications.

The authors, whose findings are published in the online version of the journal Paediatric Allergy and Immunology, said the reasons for the protective effect of sunlight were not certain.

They said one possibility is that ultraviolet (UV) irradiation can have effects on the immune system that might impact on the development of allergies.

A number of previous studies have shown that UV exposure can suppress the immune system and inflammatory activities.

But this does not explain the effect on hay fever, where the site of inflammation is not directly exposed to UV light.

‘It is possible that cells modulated by UV, following migration from the skin to other organs, might produce effects elsewhere,’ they wrote.

‘It has also been suggested sun exposure by inducing antimicrobial peptides may enhance antibacterial defences. This could benefit diseases such as eczema where bacterial colonisation of the skin is considered to play a significant role.’

They called for further studies in the area to consider both exposure to UV rays and vitamin D before sun exposure is recommended to reduce rates of allergic disease.


Breast screening 'doesn't cut deaths': Study of 40 years of mammograms show 'no evidence' they reduce chance of dying

Screening for breast cancer does not cut the chance of dying from the disease, a study claims.  The examination of 40 years of UK data produced ‘no evidence’ there was a greater fall in death rates in women who underwent mammograms.

In fact, the age group that showed the steepest fall in mortality rates were the under 40s – who are not eligible for the regular X-ray check-ups.

It is the latest study to cast doubts on the effectiveness of screening, with some experts now suggesting that advances in treatment are more likely to account for the better chances of survival.

The research was carried out by scientists from Oxford University’s Department of Public Health, who looked at the Oxford region before and after the introduction of the NHS’s screening programme in 1988.

Comparing the results with England as a whole, they found no evidence that death rates fell greater in screened women.

The greatest drop was among those under 40, where rates decreased by five per cent a year from 2000.

Lead researcher Toqir Mukhtar said although the two million women a year who undergo screening may still benefit because cancer can be detected earlier, the £75million annual cost of the programme should be reviewed.

The findings, published in the Journal of the Royal Society of Medicine, contrast with last year’s Department of Health review, which concluded that screenings cut relative mortality by 20 per cent.

Professor Michael Baum, a sceptic of screening, said: ‘The good news for women is that breast cancer death rates are falling, but it is almost entirely attributable to better treatment rather than screening.’

However, Eluned Hughes, of the charity Breakthrough Breast Cancer, said it was hard to ‘unpick’ the factors that contribute to improving survival rates.

‘It’s important that women have all the information available to them on the pros and cons of screening in order to make an informed choice that’s right for them,’ she said.

Baroness Delyth Morgan, of Breast Cancer Campaign, claimed the Department of Health’s ‘comprehensive’ review proves that screening ‘does save lives’.

And Professor Julietta Patnick, director of the NHS Cancer Screening Programmes, said check-ups play a ‘key role’ in giving women the best chance of receiving successful treatment.

‘All new evidence about the benefits and harms of breast cancer screening is kept under review to ensure that the breast screening programmes are based on the latest available evidence,’ she added.


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