Ver.1.0 (140809-18:00)

・これは、2014年7月20日にジャーナリスト向けに発行したサイエンス・アラートです。

・記事の引用は自由ですが、末尾の注意書きもご覧下さい。

＜SMC発サイエンス・アラート＞ 

喘息と子供の成長の関係についての２つの論文に対する海外専門家コメント

喘息予防のステロイド吸入と子供の成長の関係について、Cochraneデータベースに論文が掲載されたことに対して3名の研究者からコメントがありました。

Prof Jon 教授 

Professor of Environmental & Respiratory Medicine at the Institute of Occupational and Environmental Medicine, University of Birmingham
バーミンガム大学　　職業環境医学研究所　環境と呼吸医学講座

今回の研究は、ステロイド吸入が子どもの成長を抑制しうることを示しています。しかし、ステロイドは蓄積するわけではなく、その影響は小さいものです。命に関わるような喘息をコントロールするには、悪影響よりも効果の方が大きいといえます。ただし、ステロイドの種類と量については、慎重に考慮されるべきでしょう。

【コメント原文】

"These studies confirm what many have suspected, that inhaled steroids can suppress growth in children.  However, the effect seems to be small and non-cumulative and many may consider this a risk worth taking compared to the alternative which is poorly controlled, and therefore potentially life threatening, asthma. 

 

“The authors call for more research to quantify the effect more clearly but such studies will need to be large and consider a range of inhaled steroid types and doses.  In addition, care will need to be taken to assess dietary aspects of the children involved, something which has not been considered at all in previous studies where growth retardation was not the primary outcome."

Glenis Scadding 博士

Consultant Physician in Allergy & Rhinology at the Royal National Throat, Nose and Ear Hospital
耳鼻病院　アレルギー＆鼻講座　内科医

喘息で命を落とさないためにも、親はコルチコステロイド予防薬（ステロイドの一種）の使用を止めるべきではありません。ただし、過度の依存をなくすために、アレルゲンを特定する、アレルギー薬などの非ステロイド性の薬を検討するといったことで、ステロイド薬の使用量を減らす努力をすることは重要でしょう。

【コメント原文】

"It is vital that parents do not stop giving their children asthma inhaled corticosteroid preventer medication, which reduces the death rate from asthma which still kills some thousands of sufferers each year. 

 

“A risk factor for death is failure to take such medications with over-reliance on reliever treatments such as beta agonists.  What is needed is an attempt to keep the dose as low as possible by avoidance of factors, some allergic, which trigger asthma in each child, plus consideration of other preventer approaches, including treating rhinitis, use of non-steroid medications and immunotherapy. The low number of doctors trained in Allergy in the UK makes the approach to finding allergen triggers difficult."

Samantha Walker 氏

PDirector of Research and Policy at Asthma Research UK
喘息研究所　理事

日常的にステロイド吸入を行えば、制御不能な喘息発作や発作による死亡を減らすことができます。患者や家族は副作用を恐れてきましたが、今回の研究はわずかな影響しかないことを示したといえます。

【コメント原文】

“Half a centimetre in growth is a small price to pay for medicine which may save your child’s life. Uncontrolled asthma can substantially increase the likelihood of asthma attacks, hospitalisation and even death and we know that inhaled steroids, taken regularly, significantly reduce the likelihood of these events happening. For a long time now people with asthma have told us they fear the side effects of taking asthma medicines but the good news is this evidence shows only a relatively minor impact from inhaled corticosteroids. No parent should therefore stop their children taking these lifesaving medicines”.

 

‘Inhaled corticosteroids in children with persistent asthma: effects on growth’ by L Zhang et al. and ‘Inhaled corticosteroids in children with persistent asthma: dose-response effects on growth’ by AI Pruteanu et al will be published in Cochrane Database of Systematic Reviews 2014 at 00.01 Hours (BST), Thursday, July 17, 2014

有機作物と従来の作物との栄養素の違いについての論文に対する海外専門家コメント

7月15日にBritish Journal of Nutritionに掲載された、有機作物と従来の農法で作った作物に含まれる栄養素の差についての論文に対して、4名の研究者からコメントがありました。

Catherine Collins　氏

Principal Dietitian at St George’s Hospital NHS Trust
セントジョージア病院　栄養士長

有機農法と従来農法のどちらが良いかという議論は10年以上続いていますが、問題は両者をどのように比較するのかという点です。たとえば、土壌、保管、作物、輸送時間などの条件を変えれば異なる結果になってしまうでしょう。有機作物の酸化防止剤のクロロゲン酸の含有量は、従来農法とくらべると高い時も低い時もあります。したがって、「果物や野菜を付け合わせではなく、独立した一品となるだけの量の一皿を食べれば健康によい」といったことが、有機農法と従来農法の差でもたらされるとはいえません。

【コメント原文】

“Is organic food better for you than non-organic? That’s a question hotly debated for decades, and this large review of the evidence will be widely supported by the pro-organic lobby as evidence of a bigger ‘Health Halo’ with the organic cousins of the fruit and vegetable family compared to their non-organic equivalent.

 

“One of the key problems facing researchers in this field over the years is how to compare, well, apples and pears. Do you buy them at the supermarket and measure the difference in plant substances found in each type of produce at ‘point-of-sale? (so-called ‘basket studies’). Or do you choose two farms close to each other, one to grow organic and one to grow non-organic produce, and compare the two as picked? This removes the natural variation in soil richness as an influence of plant content. Or should you rely on formal experiments with sample crops? All these methods are valid but each generate very different answers depending on soil type, use of permitted plant additives to each type of produce, storage methods and time from farm to fork.

 

“That’s why in this large review the results show such a wide range of values for different plant substances. For example, the antioxidant chlorogenic acid was sometimes lower and sometimes higher in organic foods when compared to non-organic varieties. So what to do? As a dietitian I’d suggest forget the big ‘O’ title, and just enjoy your morning coffee or a juicy peach as a between meal snack as a rich source of this particular antioxidant, without the worry of how it was grown.

 

“The key plant substances that appeared higher in organic fruits and vegetables were some of the plant antioxidants. Polyphenol antioxidants such as flavanones and flavonols were higher in organic produce than non-organic versions, as were antioxidant anthocyanins. When you compare the price and availability of the organic version of foods rich in these antioxidants, paying double for organic didn’t provide you with double the antioxidant benefits – but it does reduce the amount of money left to spend on the rest of your diet.

 

“It’s also worth remembering that all of the massive national, European and international studies showing the significant health benefits of eating at least 5 portions of fruit and vegetables daily have never made a distinction between organic and non-organic varieties. When it comes to health insurance all fruits and vegetables count.  Bottom line?  Just eat more.”

Richard Mithen 教授

Leader of the Food and Health Programme at the Institute of Food Research (IFR)
食物研究所　食料健康プログラムリーダー

どのような農法でも、作物中のフェノール類（抗酸化物質の一種）の合成量を高めることはできます。ただし、フェノール類が多いからといって、健康や環境に良いとはいえません。消費者が、従来作物よりも高い価格の有機作物を買うことで（その購入量を減らせるとしても）、栄養素の増加分と相殺できるのかどうかは疑わしいでしょう。

【コメント原文】

“This paper provides some evidence that under organic agronomic regimes, there may be an increase in the concentration of certain phenolic compounds in some fruits and vegetables.  The paper also reports a decrease in protein, nitrates and fibre in the organically grown crops, which may be undesirable, and which are maybe unsurprisingly not referred to by the authors in their advocacy of organically grown produce.

 

“The increase in phenolic compounds may not be entirely unexpected due to the greater pest and pathogen damage that crops under organic systems are exposed to which can results in the induction of these toxic defence compounds.  Moreover, one can enhance the levels of phenolic compounds in crops through many different ‘organic’ or ‘conventional’ agronomic systems, or indeed through plant breeding and genetic modification, but this does not necessarily mean that the modes of production and the increases in these compounds are beneficial to health or the environment.

 

“Of greater significance is that there is no evidence provided that the relatively modest differences in the levels of some of these compounds would have any consequences (good or bad) on public health.  The references to ‘antioxidants’ and ‘antioxidant activity’, and various ‘antioxidant’ assays would suggest a poor knowledge of the current understanding within the nutrition community of how fruit and vegetables may maintain and improve health.

 

“The additional cost of organic vegetables to the consumer and the likely reduced consumption would easily offset any marginal increase in nutritional properties, even if they did occur, which I doubt.  To improve public health we need to encourage people to eat more fruit and vegetables, regardless of how they are produced.”

Tom Sanders 教授

Head of Diabetes and Nutritional Sciences Division, School of Medicine, King's College London
キングカレッジロンドン　糖尿病と栄養学講座長

この論文では、作物に含まれる抗酸化物質が必須栄養素の一部であるとみなしていますが、それは誤りです。世界がん研究基金は、果物や野菜の消費量とがんリスクの低下には相関関係があるとしていますが、その理由がフェノールを含む抗酸化物質にあるかどうかは不明だと強調しています。また、この論文は、有機作物でニトロセルロースと亜硝酸塩が減ることが健康に良いと主張していますが、最近の研究の多くはこれとは反対の結果になっています。

【コメント原文】

“This article is misleading because it refers to antioxidants in plants as if they were a class of essential nutrients, which they are not.

 

The compounds referred to are mainly plant phenolics and are produced in higher quantities when plants are environmentally stressed. Plant phenolics have both toxic as well as potential beneficial effects. Some vitamins have anti-oxidant properties such as vitamin E, vitamin C and beta-carotene but the differences between organic and conventional produce are trivial.

 

The article misleadingly suggest health benefits result from a high consumption of antioxidants particularly cancer protection.  While the World Cancer Research Foundation in its systematic reviews concluded there is a relationship between fruit and vegetable consumption and a lower risk of cancer, they did state that there was insufficient evidence to make any claim for antioxidants and plant phenolics.

 

“Polyphenols also have an adverse effect on metal absorption and are considered as anti-nutrients. For example their antioxidant properties inhibit iron and zinc absorption.

 

“The article also claims that the lower levels of nitrate and nitritein organic vegetables would be beneficial to health. However, this is opposite to more recent research, including some carried out at the University of Newcastle, which shows that nitrate in vegetables in fact lowers blood pressure because it is converted to the vasodilator nitric oxide (1).

 

“The article shows differences in cadmium concentrations in cereals but not in fruit and vegetables. Cadmium levels are dependent on the soil in which the plant is grown and haVE nothing to do with organic certification. There are naturally occurring areas (1,2) in the UK where cadmium levels of are high (e.g. Shipham in Somerset) and home-grown/organic food grown in these areas would therefore be high in cadmium.  Cadmium can be high in soils derived from spoil from former lead, zinc and tin mines. Generally, shellfish are regarded as far more important source of cadmium in the diet, especially if fished from areas where sediment is naturally high in Cadmium (ie. South Coast) or from smelting.

 

“In terms of macronutrients (i.e. protein, carbohydrate, fat) ­ the organic products contained less protein. Other nutrient differences were trivial and well inside the normal range of variation that occurs with different varieties, soil types and variations in weather.

 

“This study provides no evidence to change my views that there are no meaningful nutritional differences between conventional produced and organic crops.”

Refs:

1. Lidder S, Webb AJ. Vascular effects of dietary nitrate (as found in greenleafy vegetables and beetroot) via the nitrate-nitrite-nitric oxide pathway. Br JClin Pharmacol. 2013

Mar;75(3):677-96

2. Davies BE, Bailinger RC. Heavy metals in soils in north Somerset, England,with special reference to contamination from base metal mining in the Mendips Environ Geochem Health. 1990 Dec;12(4):291-300

3. Morgan H, Smart GA, Sherlock JC. The Shipham report. An investigation into cadmium contamination and its implications for human health. Intakes of metal.

Sci Total Environ. 1988 Aug 15;75(1):71-100.

Alan Dangour　博士

Reader in Food and Nutrition for Global Health at the London School of Hygiene & Tropical Medicine
Hygiene & Tropical Medicineロンドン校　世界的健康の食物栄養講座長

この論文の著者らは、過去20年間にわたって発表された膨大な論文を基に、有機農法と従来農法による栄養素成分の差を明らかにすることを目的としていました。しかし、20年の間に蓄積データの質が変わったにもかかわらず、良いものも悪いものも混ぜて解析したことが問題です。このような解析結果は信頼できないといわざるを得ません。

【コメント原文】

“Systematic reviews are powerful tools that are increasingly being used to help to resolve areas of controversy in science.  By bringing together all of the available evidence, critically assessing its quality, and synthesising the findings in a standardised and pre-specified manner, systematic reviews substantially reduce bias and enhance the reliability of the ‘answer’.

 

“The authors of this new systematic review that primarily aims to identify differences in nutrient content between organically and conventionally produced foods have brought together a large number of studies published over a 20 year period.  The quality of the available data varies greatly and it is therefore very surprising that, in their analysis, the authors decided to include all the data that they found, irrespective of their quality.  In fact the study authors themselves note that there are significant concerns with the consistency and reliability of some of their findings.  Mixing good quality data with bad quality data in this way is highly problematic and significantly weakens confidence in the findings of the current analysis.  It is a shame that greater care was not taken in trying to ensure that the analyses were based only on reliable and scientifically robust data from satisfactory quality studies.

 

“Furthermore, the public health significance of the reported findings have been worryingly overstated.  There is no good evidence to suggest that slightly greater antioxidant or polyphenolic intake in the human diet has important public health benefits, and there is no robust evidence to support the claim that consumption of greater amounts of these compounds reduces the risk of chronic diseases such as cardiovascular disease and cancer in human populations.

 

“All natural products vary in their composition for a wide variety of reasons.  This paper provides no convincing evidence to refute our earlier finding1, fully supported by a recent US-led systematic review2, that there are no important differences in nutrient content between organically and conventionally produced foods.”
  
Refs:
(1) Dangour AD, Dodhia SK, Hayter A et al. (2009) Nutritional quality of organic foods: a systematic review. American Journal of Clinical Medicine, 90, 680-685.
(2) Smith-Spangler C, Brandeau ML, Hunter GE et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review.  Annals of Internal Medicine, 157, 348-366.

 

* ‘Higher antioxidant concentrations and less cadmium and pesticide residues in organically grown crops: a systematic literature review and meta-analyses’ by Carlo Leifert et al. will be published in the British Journal of Nutrition at 00:01 UK time Tuesday 15th July 2014

記事のご利用にあたって

マスメディア、ウェブを問わず、科学の問題を社会で議論するために継続して
メディアを利用して活動されているジャーナリストの方、本情報をぜひご利用下さい。
「サイエンス・アラート」「ホット・トピック」のコンセプトに関してはコチラをご覧下さい。

記事の更新や各種SMCからのお知らせをメール配信しています。

サイエンス・メディア・センターでは、このような情報をメールで直接お送りいたします。ご希望の方は、下記リンクからご登録ください。（登録は手動のため、反映に時間がかかります。また、上記下線条件に鑑み、広義の「ジャーナリスト」と考えられない方は、登録をお断りすることもありますが御了承下さい。ただし、今回の緊急時に際しては、このようにサイトでも全ての情報を公開していきます）【メディア関係者データベースへの登録】 http://smc-japan.org/?page_id=588

記事について

○ 私的／商業利用を問わず、記事の引用（二次利用）は自由です。ただし「ジャーナリストが社会に論を問うための情報ソース」であることを尊重してください（アフィリエイト目的の、記事丸ごとの転載などはお控え下さい）。

○ 二次利用の際にクレジットを入れて頂ける場合（任意）は、下記のいずれかの形式でお願いします：
・一般社団法人サイエンス・メディア・センター　・（社）サイエンス・メディア・センター
・（社）SMC　　・SMC-Japan.org

○ この情報は適宜訂正・更新を行います。ウェブで情報を掲載・利用する場合は、読者が最新情報を確認できるようにリンクをお願いします。

お問い合わせ先

○この記事についての問い合わせは「御意見・お問い合わせ」のフォーム、あるいは下記連絡先からお寄せ下さい：
一般社団法人 サイエンス・メディア・センター（日本）　Tel/Fax: 03-3202-2514