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科學技術
Slim pickings
重拾苗條
Evidence that the problem of obesity starts in the womb
有證據證明肥胖始于子宮
IN THE late 1980s David Barker, a British doctor, suggested that what a woman eats when she is pregnant shapes her child's physiology for life.
上世紀80年代末，英國醫生大衛巴克爾說婦女懷孕期間飲食會塑造孩子未來的生理機能。
He called the idea fetal programming.
他稱之為胎兒計劃。
Such programming would allow an individual to make optimum use of available nutrients, on the assumption that his own diet will be similar to his mother's.
這一計劃讓每個人以最佳方式利用營養，他假定自己的飲食和母親的相似。
If it was not similar, though, there could be problems.
如果不相似，就有問題了。
Dr Barker speculated that fetal programming—in mesalliance with the spread of fatty, sugary foods over recent decades—might explain the epidemic of obesity, heart disease and late-onset diabetes that plagues many rich countries.
巴克爾推測胎兒計劃與偏遠地區普遍的高脂肪，含糖飲食的有關系。這也許就解釋了肥胖，心臟病以及折磨很多富裕國家的糖尿病。
It is a neat theory, but hard to prove.
這是很明確的結論，但卻很難證明。
On October 29th, though, Sir Peter Gluckman, an endocrinologist and evolutionary biologist at the University of Auckland, in New Zealand, presented evidence to support it at a conference organised in Lausanne by Nestlé, a Swiss food company.
但在10月29日，新西蘭奧克蘭大學內分泌和進化生物學學家彼得格拉克曼，在瑞士洛桑雀巢食品公司一個會議上提供了證據。
Dr Gluckman carried out his study in Jamaica, in collaboration with Terrence Forrester, of the University of the West Indies.
格拉克曼博士在牙買加進行了試驗，并且與西印度大學特倫斯福倫斯特合作。
He picked Jamaica because malnutrition is endemic there.
他選擇牙買加是因為營養不良是那里的地方病。
That allows the theory of fetal programming to be tested by finding out whether those who experienced malnutrition in the womb respond differently to food than those who were properly fed.
這樣一來，胎兒計劃就能通過研究母體內營養不良與營養充足是否影響孩子的食物選擇來證明。
Dr Gluckman and Dr Forrester began their study by looking at people who had survived childhood malnutrition.
格拉克曼和福倫斯特從研究兒童營養不良的幸存者開始。
Symptoms normally manifest themselves in one of two ways, known as marasmus and kwashiorkor.
常常表現為一種或兩種癥狀，身體衰弱癥和夸希奧科病。
Children with marasmus are simply emaciated.
衰弱癥的孩子只是瘦而已。
One significant difference between the two syndromes is that children with marasmus are twice as likely to survive malnutrition as those with kwashiorkor.
夸希奧科病的孩子下腹則膨脹得像電視上那些饑荒浮腫的人。
Dr Gluckman and Dr Forrester looked at 240 people aged between 25 and 40 who had survived one syndrome or the other as children, and found a systematic difference between them.
格拉克曼和福倫斯特博士觀察了240個患有綜合癥的25到40歲之間成人和兒童，發現了二者有規律性的差別。
The marasmus survivors tended to have had low birthweights.
身體衰弱癥的患者出生體重偏輕，
The kwashiorkor group had normal birthweights. Low birthweight is an indication of a malnourished mother.
夸希奧科病的人群出生體重正常。出生體重輕就表示母親營養不良。
Dr Gluckman and Dr Forrester thus hypothesise that the capacity for a marasmus-style response to malnutrition, with its higher survival rate, is programmed into fetuses by maternal malnourishment.
兩位博士據此假設身體虛弱消瘦體質是因為營養不良，消瘦體質存活率很高，計入母親營養不良所致。
Fetuses carried by well-nourished mothers do not, as it were, anticipate the risk of malnutrition, and thus respond to it less well.
福倫斯特博士研究營養充足的母親則不像營養不良的母親那么易導致孩子營養不良，孩子也就不容易得消瘦癥了。
That suggests fetal programming is a real phenomenon.
這些研究證明胎兒計劃確實存在。
But can it help explain obesity, diabetes and so on?
但它能否解釋肥胖，糖尿病等病癥呢？
To investigate this, the two researchers then offered their volunteers foods that were either high in protein and low in fat, or low in protein and high in fat—but which, crucially, tasted the same, so that they did not know what they were eating.
為了研究這個問題，兩位博士又給志愿者食用高蛋白低脂肪或者低蛋白高脂肪的食物，關鍵的是味道一樣，志愿者就不知道自己吃的是什么了。
They found that those who had survived marasmus ate differently from those who had survived kwashiorkor.
他們發現得過消瘦癥的人與得過夸希奧科病的人吃的不一樣。
The bodies of marasmus survivors seemed to demand more protein in their food.
前者的食物似乎需要更多蛋白質。
When offered a diet low in protein and high in fat, they consumed more of it.
如果給他們低蛋白高脂肪的食物，他們就會吃得更多。
That kept their protein intake constant, but meant they were eating 500 calories a day more than a normal maintenance diet.
以此保證蛋白質的攝入量，同時就意味著他們每天比正常人多攝入500卡路里的食物。
Kwashiorkor survivors did not overeat in this way.
得過夸希奧科病的人就不會這樣暴飲暴食。
This, then, may be the key that unlocks the puzzle.
以上就是解開謎團的關鍵。
Diets of the past would tend to have been lean.
過去的飲食太不平衡了如果時間決定一切，
Anticipating scarcity by overeating in times of plenty would be no bad thing if times of scarcity were a real risk.
短期的飲食過量導致的營養缺乏并不會有嚴重后果。
Bodies that expected food to be plentiful, by contrast, should ration themselves to avoid the consequences of chronic overeating.
與此相反，對于想吃大量食物的人，則應該約束自己避開長期性飲食過量。
An inability to do that is the price paid for protection from famine by those predisposed to marasmus.
做而易患消瘦癥的婦女因為窮又買不起蛋白質足的食物，就沒法讓自己營養充足了。
This study thus makes a prediction: as diets become high in sugar and fat in places where malnutrition was once common, those who suffered marasmus as children will become overweight more rapidly than those who suffered kwashiorkor.
這項研究預測：在高脂肪高糖類的地區營養不足很常見，那些得消瘦癥的人，比如兒童，就會比夸希奧科病患者更快肥胖起來。
If that turns out to be the case, it will be evidence that Dr Barker was right. What is not yet clear is whether the children of today's overfed westerners will experience programming in the opposite direction, and have their appetites restricted.
如果真實情況就是這樣，就證明巴克爾教授結論正確。對營養過剩的西方人來說，小孩在母親肚子里的時候是不是與非洲孩子情況相反，平時是不是注意了飲食限制，目前則尚不清楚。
