想要瘦身 少吃脂肪是關鍵
摘錄自：天下雜誌 經濟學人電子報 2014/3/28
2014-03-25 Web
only 作者：經濟學人
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| 圖片來源：flickr.com/photos/pthread/ |
最近發表的一篇論文，可能會讓嚴格控管飲食的人十分迷惑。該論文針對總研究對象超過60萬人、共72項研究進行整合分析，也就是將各項研究作為單一資料點，進行整合統計分析。
部分研究與民眾吃什麼、或民眾表示他們吃了什麼有關，部分與民眾血液中的各種脂肪水準有關，部分則與兩者都有關。每項研究都檢視了前述事實與心臟健康的關係。
劍橋大學的喬杜里（Rajiv Chowdhury）團隊發現，其中一種反式脂肪確實與心臟疾病有關，但他們亦強調，他們檢視的研究中，只有5項研究在這方面提出了恰當數據。然而，研究的結果與一般的常見並不相同。
他們沒有找到證據，無法證明心臟疾病與食用飽和脂肪，或是血液飽和脂肪酸水準偏高有關。Omega-3脂肪酸是目前健康飲食的當紅炸子雞，但同樣地，他們也沒有找到omega-3脂肪酸有助對抗心臟疾病的證據。
市面上銷售的omega-3脂肪，大多是以營養補充品的形式裝在膠囊中發售，這讓omega-3脂肪比其他脂肪更易於研究吃與不吃間的差異；因此，喬杜里博士的整合分析是以這類研究為基礎。事實上，目前就有兩項大型的omega-3補充品研究正在進行，但這類試驗難以應用於其他脂肪，因為那些脂肪都是飲食的一部分。許多人不介意定期服用膠囊或不服用膠囊，但想說服他們讓其他人決定數年的飲食，自然難得多，而進行這類實驗就得辦到這點才行。
但這正是心臟疾病的問題之一。大多數人沒有那麼強的意志力，無法堅守他人訂出的食譜，規則再簡單也沒有用。不過，相對簡單、混合各種食材的食譜，再加上適度運動，似乎還是擁有健康生活的最佳之道。喬杜里博士團隊並不是說，吃下多少脂肪與心臟病的風險無關，但他們的研究確實顯示，除了反式脂肪之外，脂肪的種類並不重要。（黃維德譯）
©The Economist
Newspaper Limited 2014
The Economist
Nutrition
Fat chance
By The Economist
From The Economist
Published: March 25, 2014
Mar 22nd 2014 |
From the print edition
How much fat you
eat matters to your health. What sort of fat matters less.
THOSE who
micromanage their diets instead of following Michael Pollan's sensible rule of
thumb—eat food, not too much, mostly plants—may be thrown into confusion by a
paper just published in the Annals of Internal Medicine. It describes a
meta-analysis (a technique which uses entire studies as single data points in
an overarching statistical analysis) of 72 pieces of research involving more
than 600,000 people.
Some of these were
of what those people ate, or said they ate. Some were of the levels of various
fats circulating in their bloodstreams. Some were of both. All had looked for
relations between these facts and a person's subsequent cardiac health. And the
meta-analysis comes to what will, to many, be counterintuitive conclusions.
Rajiv Chowdhury of
Cambridge University and his colleagues found that one bugbear, trans-fats, are
indeed associated with heart disease—though they caution that only five of the
studies they looked at had pertinent data on these. Other common beliefs,
however, were not supported.
They found no
evidence that eating saturated fats or having high levels of circulating
saturated fatty acids (the digested products of such fats) had any effect on
cardiac disease. Nor did they find that omega-3 fatty acids, the current
poster-boys of healthy eating, protect against heart disease.
Omega-3 fats are
widely sold in capsule form as food supplements. This makes them easier than
other fats to incorporate into experiments of the sort that administer
something to one group while denying it to another. In their case, therefore,
Dr Chowdhury's meta-analysis was based on such experiments. Indeed two big, new
trials of omega-3 supplements are going on at the moment. But such trials are
hard to do on other sorts of fat, since these are simply part of people's
diets. Many people do not mind being asked either to pop a capsule regularly,
or to refrain from doing so. It is understandably harder to persuade them to
let someone else decide their entire food consumption for the several years
needed to conduct trials like these.
This sort of
unwillingness is, indeed, one reason heart disease is a problem. Most people do
not have the willpower to stick to a diet, any diet, prescribed by someone
else—even the simple one offered by Mr Pollan, who is the author of "Food
Rules: An Eater's Manual". But eating a reasonably Spartan,
mixed-ingredient diet, along with a regimen of moderate exercise, still seems
the best route to a long and healthy life. Dr Chowdhury and his colleagues are
not suggesting that the amount of fat you eat has no bearing on your risk of
having a heart attack. What their research does suggest is that, trans-fats
aside, the type of fat may not matter.
From the print
edition: Science and technology
©The Economist
Newspaper Limited 2014
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