研究：吃糖過多會引發抑鬱

According to new research, too much sugar doesn't just lead to weight gain, but also depression, anxiety and stress.

糖吃起來或許很甜——但是它對身體的影響卻與甜相去甚遠。新研究表明，過量的糖分不僅導致體重的增長，也會導致抑鬱、焦慮和壓力。

Eating a diet high in fructose as a teenager makes depression and anxiety worse, scientists found.

科學家發現，青少年攝入高糖分食物會加重抑鬱和焦慮情緒。

It also alters how the brain response to stress, they said.

他們說，過高的糖攝入也會改變大腦對壓力的應對方式。

Fructose is a sugar found naturally in fruits and vegetables but is also added to processed foods and drinks - from biscuits to ice cream.

水果和蔬菜中富含天然果糖，但加工食品和飲品中，比如餅乾和冰淇淋，都會添加果糖。

Scientists have found fructose appears to be linked to serious modern epidemics such as cancers, heart disease, hypertension, kidney damage, type 2 diabetes and even dementia.

他們發現果糖似乎與癌症、心臟病、高血壓、腎功能損傷、2型糖尿病甚至是老年癡呆症有關。

But now researchers say it also stimulates pathways in the brain that affect how it responds to stress, which have important effects for behaviour.

然而，目前研究人員稱果糖對大腦中的神經通路也有刺激作用。這些神經通路會影響大腦對壓力的應對，從而對人的行爲具有重大影響。

It can worsen the symptoms related to depression and anxiety, they said.

研究人員說果糖會加重與抑鬱和焦慮相關的症狀。

These effects are particularly concerning during the teenage years, when a person’s stress response develops.

青春期正是壓力應對能力發展階段，這些危害對青少年的影響尤爲令人擔心。

If the body’s stress response becomes too sensitive, teenagers risk growing up susceptible to high levels of stress.

如果機體對於壓力的反應過於敏感，青少年面臨着成年後面對高壓更爲脆弱的風險。

Prolonged exposure to stress can raise blood pressure, suppress the immune system, increase the risk of heart attack and stroke, contribute to infertility, and speed up the aging process.

長期處於壓力狀態會導致血壓升高、免疫力下降，增加心臟病和中風風險，導致不孕不育，加速衰老過程。

As part of the study, lead author Constance Harrell of Emory University in Atlanta, US, and her team gave teenage and adult rats either a standard diet, or one high in fructose.

作爲研究的一部分，調查報告的主要撰寫人、美國亞特蘭大埃默裏大學（Emory University）的康斯坦斯•哈勒爾（Constance Harrell）和她的團隊給小鼠和成年鼠餵食了普通食物或是高果糖食物。

After 10 weeks, they exposed the rats to stress, forcing them to swim or putting them in an elevated maze.

十週後，他們對老鼠施加壓力，迫使他們游泳或是將它們置於高架迷宮中。

The teenage rats fed the high-fructose had a different stress hormone response to the test, including producing more of the stress hormone cortisol than the adult rats.

餵食高果糖的小鼠對測試表現出不同的壓力激素反應，包括比成年鼠產生更多的壓力激素皮質醇。

They showed depressed and anxious behaviour in response to the tests.

在測試反應中，他們表現出抑鬱和焦慮行爲。

Scientists found that a genetic pathway in the brain that plays a key role in regulating the way it responds to stress was also altered as a result of the diet.

大腦中的遺傳神經迴路在調節大腦對壓力的應對方式中扮演重要角色。科學家發現遺傳神經迴路也會因飲食而改變。

The findings indicate that eating a diet high in fructose throughout the teenage years may exacerbate depressive behaviours, researchers said.

研究者稱，調查結果表明整個青少年時期都吃富含高果糖的飲食會加劇抑鬱行爲。

They may also affect the way the body and brain responds to stress, they added.

他們補充說，這些高果糖飲食可能也會影響機體和大腦對壓力的應對方式。

‘Our results offer new insights into the ways in which diet can alter brain health and may lead to important implications for adolescent nutrition and development,' Ms Harrell concluded.

“我們的研究結果對飲食會改變大腦健康以及可能對青少年營養與成長埋下重大隱患提出了新的見解。”哈勒爾女士說。

HOW THE BODY REACTS TO FRUCTOSE

機體是怎樣對果糖做出反應的？

Although it is a simple sugar, glucose, rather than fructose is the body’s preferred energy source.

雖然葡萄糖只是一種單糖，但是身體最佳的能源卻是葡萄糖而非果糖。

Excess fructose in the body is turned into fat, which can lodge in the liver, leading to non-alcoholic fatty liver disease.

身體中過量的果糖會轉化爲脂肪，積累在肝臟中，最終導致非酒精性脂肪肝。

Fructose puts an extra load on the liver, which in turn, prompts a range of problems, including raised levels of fat in the bloodstream.

果糖會對肝臟造成額外負擔，相應的也就導致了血脂升高等一系列問題。

The sugar can also lead to insulin resistance- where the body stops detecting insulin levels in the blood - and so produces even more insulin.

糖類也會導致胰島素抵抗——這時機體停止檢測血液中胰島素含量——因而會分泌更多胰島素。

Insulin resistance is one of the key feature of metabolic syndrome, which could lead to type 2 diabetes, obesity and heart disease.

胰島素抵抗是代謝症候羣的主要特徵之一，它會導致2型糖尿病、肥胖和心臟病。

High levels of insulin in the blood also blocks the action of 'hunger hormone' leptin, which tells the brain when fat cells have enough energy.

“飢餓激素”——瘦素，能幫助大腦識別脂肪細胞何時能量充足。血液中高濃度的胰島素同樣會阻礙瘦素作用的發揮。

So high levels of insulin lead to leptin resistance and therefore obesity.

因此，高濃度胰島素會導致瘦素抵抗，肥胖也隨之而來。