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

糖吃起来或许很甜——但是它对身体的影响却与甜相去甚远。新研究表明，过量的糖分不仅导致体重的增长，也会导致抑郁、焦虑和压力。

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

科学家发现，青少年摄入高糖分食物会加重抑郁和焦虑情绪。

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

他们说，过高的糖摄入也会改变大脑对压力的应对方式。

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，但加工食品和饮品中，比如饼干和冰淇淋，都会添加果糖。

Scientists have found fructose appears to be linked to serious modern epidemics¹ such as cancers, heart disease, hypertension, kidney damage, type 2 diabetes² and even dementia.

他们发现果糖似乎与癌症、心脏病、高血压、肾功能损伤、2型糖尿病甚至是老年痴呆症有关。

But now researchers say it also stimulates³ pathways in the brain that affect how it responds to stress, which have important effects for behaviour.

然而，目前研究人员称果糖对大脑中的神经通路也有刺激作用。这些神经通路会影响大脑对压力的应对，从而对人的行为具有重大影响。

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

研究人员说果糖会加重与抑郁和焦虑相关的症状。

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

青春期正是压力应对能力发展阶段，这些危害对青少年的影响尤为令人担心。

If the body’s stress response becomes too sensitive, teenagers risk growing up susceptible⁴ to high levels of stress.

如果机体对于压力的反应过于敏感，青少年面临着成年后面对高压更为脆弱的风险。

Prolonged exposure to stress can raise blood pressure, suppress the immune system, increase the risk of heart attack and stroke, contribute to infertility⁵, and speed up the aging process.

长期处于压力状态会导致血压升高、免疫力下降，增加心脏病和中风风险，导致不孕不育，加速衰老过程。

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.

作为研究的一部分，调查报告的主要撰写人、美国亚特兰大埃默里大学（Emory University）的康斯坦斯•哈勒尔（Constance Harrell）和她的团队给小鼠和成年鼠喂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 maze⁶.

十周后，他们对老鼠施加压力，迫使他们游泳或是将它们置于高架迷宫中。

The teenage rats fed the high-fructose had a different stress hormone⁷ response to the test, including producing more of the stress hormone cortisol than the adult rats.

喂食高果糖的小鼠对测试表现出不同的压力激素反应，包括比成年鼠产生更多的压力激素皮质醇。

They showed depressed⁸ and anxious behaviour in response to the tests.

在测试反应中，他们表现出抑郁和焦虑行为。

Scientists found that a genetic⁹ 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.

大脑中的遗传神经回路在调节大脑对压力的应对方式中扮演重要角色。科学家发现遗传神经回路也会因饮食而改变。

The findings indicate that eating a diet high in fructose throughout the teenage years may exacerbate¹⁰ depressive behaviours, researchers said.

研究者称，调查结果表明整个青少年时期都吃富含高果糖的饮食会加剧抑郁行为。

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

他们补充说，这些高果糖饮食可能也会影响机体和大脑对压力的应对方式。

‘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.

“我们的研究结果对饮食会改变大脑健康以及可能对青少年营养与成长埋下重大隐患提出了新的见解。”哈勒尔女士说。

HOW THE BODY REACTS TO FRUCTOSE

机体是怎样对果糖做出反应的？

Although it is a simple sugar, glucose¹¹, rather than fructose is the body’s preferred energy source.

虽然葡萄糖只是一种单糖，但是身体最佳的能源却是葡萄糖而非果糖。

Excess fructose in the body is turned into fat, which can lodge¹² in the liver, leading to non-alcoholic fatty liver disease.

身体中过量的果糖会转化为脂肪，积累在肝脏中，最终导致非酒精性脂肪肝。

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

果糖会对肝脏造成额外负担，相应的也就导致了血脂升高等一系列问题。

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

糖类也会导致胰岛素抵抗——这时机体停止检测血液中胰岛素含量——因而会分泌更多胰岛素。

Insulin resistance is one of the key feature of metabolic¹³ syndrome¹⁴, which could lead to type 2 diabetes, obesity¹⁵ and heart disease.

胰岛素抵抗是代谢症候群的主要特征之一，它会导致2型糖尿病、肥胖和心脏病。

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.

“饥饿激素”——瘦素，能帮助大脑识别脂肪细胞何时能量充足。血液中高浓度的胰岛素同样会阻碍瘦素作用的发挥。

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

因此，高浓度胰岛素会导致瘦素抵抗，肥胖也随之而来。