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zoom RSS 葉酸は先天性心疾患を予防する/カナダ

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 パンに葉酸添加を義務づけたことで、先天性心疾患のリスクが低下したとのカナダからの報告
 1998年に小麦粉とパスタに対する添加が始まり、ケベック州の新生児の先天性心臓疾患の発症率が低下した。欧州での強化導入を要求している。
 しかし反対論があり、他のビタミンBが不足していると高齢者に害をもたらす可能性がある。極端な場合、神経系の不可逆障害を引きおこす可能性がある。また、大腸ガンその他のある種のガンのリスクを増大させる可能性がある。
 2007年に、英国監視グループとFSA食品基準局はパンまたは小麦粉の葉酸強化を推奨することに合意した。その後専門家のワーキンググループが葉酸の効果を試験してきた。
 葉酸はレバーや緑色葉物野菜に多く含まれるビタミンBの一つである。妊婦や妊娠を計画している女性は葉酸摂取が推奨され、先天性神経管障害のリスクを軽減できる。
 最新の研究では、新生児の先天性心臓障害のリスクを減らす可能性がある。強化開始以来、年に6%の割合で重症の先天性心疾患が減少した。神経管障害では9%だった。
 潜在的に危険なビタミンB12欠乏症が、葉酸の高用量摂取によりマスクされてしまう危険性がある。
 強化による利点がリスクを上回るかどうかを十分吟味する必要があり、証拠がまだ不充分である。
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光沢を失う葉酸/二分脊椎 大腸がん
http://kurie.at.webry.info/200905/article_18.html
葉酸添加に対する警告
http://kurie.at.webry.info/200710/article_71.html
妊婦の「葉酸」摂取進まず/先天障害リスク
http://kurie.at.webry.info/200708/article_24.html
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Page last updated at 23:50 GMT, Tuesday, 12 May 2009 00:50 UK
Folic acid protects baby hearts
http://news.bbc.co.uk/2/hi/health/8045212.stm

画像Bread
Flour can be fortified with folic acid

Mandatory fortification of bread with folic acid would slash the risk of babies being born with a heart problem, experience from Canada shows.

Rates of severe congenital heart defects among newborns in Quebec fell significantly after the move to fortify flour and pasta began in 1998.

The British Medical Journal online study lends support to calls for introducing fortification to Europe.

But others argue against this, saying it would inevitably harm some people.

The fear is that adding folic acid to products like bread could harm some elderly people if they are deficient in other B vitamins.

Personally, I do not think mandatory fortification is the way forward. It is like using a sledge hammer to crack a nut
Dr Sian Astley, a scientist for the Institute of Food Research

In extreme cases, this can cause irreversible damage to the nervous system.

There is also concern that it may also increase the risk of certain cancers, including bowel cancer, in some people.

In 2007 the UK's watchdog, the Food Standards Agency, agreed with expert recommendations to fortify bread or flour with folic acid.

Since then, at the request of the Chief Medical Officer, an expert working group on folate has been considering the results of recent trials looking at the effect of folic acid on the risk of some types of cancer.

The group is expected to report back to Sir Liam Donaldson this summer.

Risk reduction

Folic acid is a synthetic form of folate, a B vitamin found in a wide variety of foods including liver and green leafy vegetables.

Pregnant women and those trying to conceive are already advised to take folic acid supplements to reduce the risk that their baby will have a "neural tube" birth defect like spina bifida.

But uptake is not ideal, particularly because some pregnancies are unplanned and can go unnoticed for some weeks.

The latest work suggests folic acid also cuts the risk of baby heart defects.

In the seven years after fortification was introduced there was a 6% drop per year in the birth prevalence of severe heart defects.

This compares with a 9% drop in neural tube defects.

Writing in the BMJ, lead author Professor Louise Pilote of McGill University in Montreal, said: "Given that severe congenital heart defects require complex surgical interventions in infancy and are associated with high infant mortality rates, even a small reduction in the overall risk will significantly reduce the costs associated with the medical care of these patients and the psychological burden on patients and their families."

Weighing the risks

The British Heart Foundation said the risks and benefits of fortification must be carefully weighed.

A spokeswoman said: "This Canadian study shows that when folic acid was added to flour and pasta the number of babies born with certain severe heart conditions was reduced.

"While the decrease in babies born with heart conditions during this time is statistically significant, many children were still born with congenital heart disease.

"This must be taken into account when considering the benefits of routinely introducing folic acid to flour and pasta in the UK.

"Especially because routine introduction could pose a risk to some elderly people as potentially dangerous vitamin B12 deficiency can be masked by high intake of folic acid."

Alternative suggested

Dr Sian Astley, a scientist for the Institute of Food Research, said: "Personally, I do not think mandatory fortification is the way forward. It is like using a sledge hammer to crack a nut.

"It would reduce ill health in children but there are cautionary issues.

"An alternative would be to fortify only certain foods and clearly label them so consumers can make the choice. Co-fortification with other B vitamins would be another sensible option."

She said the IFR believes there is still insufficient evidence to make a decision about whether the benefits of fortification would outweigh the risks.

---------------------------------------------------
Published 12 May 2009, doi:10.1136/bmj.b1673
Cite this as: BMJ 2009;338:b1673
Research
Prevalence of severe congenital heart disease after folic acid fortification of grain products: time trend analysis in Quebec, Canada

Raluca Ionescu-Ittu, PhD candidate1, Ariane J Marelli, associate professor of medicine, director2,3, Andrew S Mackie, assistant professor of paediatrics4, Louise Pilote, professor of medicine, director2,5

1 Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Canada, 2 McGill University, Montreal, Canada, 3 McGill Adult Unit for Congenital Heart Disease Excellence (MAUDE), McGill University Health Centre, Montreal, Canada, 4 University of Alberta, Division of Cardiology, Stollery Children’s Hospital, Edmonton, Canada, 5 Division of General Internal Medicine, McGill University Health Centre, Montreal, Canada

Correspondence to: L Pilote, Royal Victoria Hospital, V Building, 687 Pine Avenue West, Room V2.17, Montreal, QC, Canada H3A 1A1 louise.pilote@mcgill.ca
Objective To investigate whether the 1998 government policy for mandatory fortification of flour and pasta products with folate was followed by a reduction in the prevalence of severe congenital heart defects.

Design Time trend analysis.

Setting Province of Quebec, Canada.

Participants Infants born in 1990-2005 identified with severe congenital heart defects (tetralogy of Fallot, endocardial cushion defects, univentricular hearts, truncus arteriosus, or transposition complexes) in Quebec administrative databases.

Methods Data analysed in two time periods (before and after fortification). Birth prevalence measured annually as infants (live and stillbirths) with severe congenital heart defects per 1000 births in Quebec. Changes in the birth prevalence from the period before to the period after fortification were estimated with Poisson regression.

Results Among the 1 324 440 births in Quebec in 1990-2005 there were 2083 infants born with severe congenital heart defects, corresponding to an average birth prevalence of 1.57/1000 births. Time trend analysis showed no change in the birth prevalence of severe birth defects in the nine years before fortification (rate ratio 1.01, 95% confidence interval 0.99 to 1.03), while in the seven years after fortification there was a significant 6% decrease per year (0.94, 0.90 to 0.97).

Conclusions Public health measures to increase folic acid intake were followed by a decrease in the birth prevalence of severe congenital heart defects. These findings support the hypothesis that folic acid has a preventive effect on heart defects.

(c) Ionescu et al 2009
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
http://creativecommons.org/licenses/by-nc/2.0/

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