伊萊恩·K.豪利 張爽

Whether for philosophical or health reasons， some people are opting to stop consuming animals and are adopting a vegan diet. This approach to eating eschews all animal products， including meat， fish， milk， eggs and even honey.

Making the switch can be a challenge for people who are accustomed to incorporating dairy and meat in their diet， but it could offer some health benefits. It might even change your body in certain ways.

But how it might change depends on what you were eating before， says Dena Champion， a registered dietitian at the Ohio State University Wexner Medical Center in Columbus.

“The term ‘vegan’ as it pertains to diet only means that one does not eat any animal products. It doesn’t inherently equal healthy， but it can be a healthy diet，” especially if you’re coming from a less healthful way of eating， she explains.

“If you’re already eating a diet heavy in plants with minimal animal products， you may see very few changes，” Champion says. But， “if you go from eating a diet heavy in animal meat and dairy and change to a diet consisting of high amounts of fruits， vegetables and whole grains，” you may see changes in several areas.

Reduced body weight

“Eliminating any major food group， in this case animal proteins， can cause a calorie deficit，” says Kailey Proctor， an oncology dietitian with the Center for Cancer Prevention and Treatment at St. Joseph Hospital in Orange County， California.

Many Americans consume a diet that’s heavy in processed， high-fat meats， which also tend to be high in calories and saturated fat. Removing those animal proteins can mean a reduction in calories， Proctor explains.

Instead of high-fat and calorie-dense proteins like bacon and beef， vegans get their protein from plant-based sources such as： Tofu. Tempeh1. Beans. Soy milk. Legumes.

“This can lead to weight loss， and considering that two-thirds of Americans are overweight or obese， this can have a positive impact on body composition2 and health markers，” such as blood pressure and triglyceride （a type of fat） levels in the blood， Proctor says.

Improved heart and vascular health

“Diets high in fruits， vegetables and whole grains can lower triglycerides and cholesterol thereby reducing the risk of heart disease，” Procter says. Plant-based protein sources such as tofu and tempeh have no cholesterol3—cholesterol is a fatty substance that only comes from animal products. It can build up in the vascular system， leading to blockages that could trigger heart attacks or strokes. Eliminating animal products removes cholesterol from the diet， which could reduce your risk of heart disease.

What’s more， a vegan diet tends to be lower in sodium than some other types of diets because most fruits and vegetables are low in sodium. Because sodium can increase blood pressure levels， lowering your consumption of salt and sodium may also contribute to better heart and vascular health.

Improved blood sugar control

Because being overweight or obese is a major risk factor for developing diabetes， losing weight can lower that risk. One study published in the journal Nutrients in 2018， for example， followed overweight people with no history of diabetes after they switched to a vegan diet for 16 weeks. Those people saw improvements in insulin4 sensitivity and better function of the pancreatic5 cells responsible for producing and releasing insulin. This led to improvements in blood sugar levels.

Reduced joint pain

Fruits and vegetables contain certain compounds called phytonutrients6 that have an anti-inflammatory effect on cells. Also called antioxidants7， these compounds can help reduce the joint pain， swelling and tenderness associated with arthritis and other chronic conditions of the joints.

In addition， if you’re overweight， losing weight can help reduce stress on achy joints in the lower body. The hips， knees and ankles bear the weight of the whole body， so weighing less means less pressure—in some cases， a lot less pressure—on the arthritic joint.

Improved bowel health

Because a healthy vegan diet emphasizes consumption of high-fiber foods like fruit， vegetables and whole grains， that can lead to better gut health and regularity.

High-fiber， whole grain foods contain prebiotics， which are natural， non-digestible compounds that help support the growth of helpful bacteria in the gut—i.e.， you need prebiotics to form probiotics， which are those beneficial bacteria.

When you’re consuming prebiotics and probiotics in adequate amounts， that can help regulate gut health， which science is increasingly learning can contribute to overall good health. High fiber foods also add bulk to the stool， which can make for better regularity and improved gastrointestinal8 health.

Reduced cancer risk

There’s also the potential to reduce your risk of developing cancer， Proctor says. “Vegan diets， when planned correctly， are also very high in fruits， vegetables and whole grains. These plant-based foods have been shown to reduce the risk of cancer due to their high antioxidant and phytonutrient content.”

Covering your nutritional bases

It’s important to make sure you’re getting adequate amounts of certain nutrients that may be more difficult to get when following a strict vegan diet， Proctor says.

“The term ‘vegan’ doesn’t exactly mean healthy，” Proctor cautions. “You can have a vegan cookie，” for example， “but at the end of the day， it’s still a cookie.”

As with any other type of diet， the emphasis should always be on consuming whole， fresh foods as much as possible. Read labels on any prepared or processed foods so you know what you’re eating.

And Champion recommends transitioning to a vegan lifestyle slowly. “It can feel really overwhelming to go from eating animal products at every meal to eliminating them all overnight. Allow yourself time to find recipes and make a plan.”

Proctor also recommends “combining protein sources to make complete sources of protein.” For example， combining rice and beans， or peanut butter and jelly on wheat bread can provide the full complement of amino acids your body needs to keep muscles strong.

Similarly， look to support adequate protein intake by adding soy foods including tofu， tempeh， edamame， soy milk and soy nuts.

You also need to be sure you’re getting enough vitamin B12， which can be problematic for people who follow a vegan diet because vitamin B12 “is only found in animal proteins，” Proctor explains. “Vitamin B12 plays a role in red blood cell production， synthesis of DNA and RNA as well as keeping our nervous system healthy.”

出于哲學(xué)或是健康原因，有些人打算不再吃肉食，而改吃純素食。這一飲食方式戒絕所有的動物制品，包括肉類、魚類、牛奶、雞蛋，甚至蜂蜜。

對吃慣了奶制品和肉類的人來說，改吃純素食是一種挑戰(zhàn)，但是，吃純素食對健康有一定益處，甚至能在某些方面改變你的身體。

不過，身體如何改變?nèi)Q于之前的飲食習(xí)慣，俄亥俄州立大學(xué)韋克斯納醫(yī)學(xué)中心注冊營養(yǎng)師德娜·錢皮恩表示。該大學(xué)位于哥倫布市。

“當(dāng)‘純素食’指飲食習(xí)慣時，只意味著不吃任何動物制品。素食本身與有益健康并不等同，但它可以成為一種健康的日常飲食”，尤其是在之前的飲食習(xí)慣不太健康的情況下，她解釋道。

“如果日常飲食已經(jīng)是以植物為主，只吃極少的動物制品，那么改吃純素食帶來的變化可能很小?！卞X皮恩說。不過，“如果是由平時主要吃肉類、奶制品，改為吃大量水果、蔬菜和全谷物”，那你的身體也許會在若干方面發(fā)生變化。

體重減輕

加利福尼亞州奧蘭治縣圣約瑟醫(yī)院癌癥防治中心的腫瘤學(xué)營養(yǎng)師凱莉·普羅克特說：“減少任何一大類食物的攝入量都會導(dǎo)致熱量不足，這里說的是減少動物蛋白?！?/p>

很多美國人平時吃大量加工肉制品，這些肉制品脂肪含量高，熱量和飽和脂肪含量也很高。普羅克特解釋道，減少這些動物蛋白的攝入可能意味著熱量的減少。

純素食者攝入的蛋白質(zhì)來自植物性食物，例如豆腐、豆豉、豆子、豆奶、豆類植物，而不是培根、牛肉這類食物中的高脂肪、高熱量蛋白質(zhì)。

普羅克特表示：“這能使體重減輕?？紤]到有三分之二的美國人超重或肥胖，吃純素食對體成分和健康指標(biāo)都有積極影響。”指標(biāo)包括血壓和血液中甘油三酸酯（一種脂肪）的水平。

心血管健康改善

普羅克特說：“以水果、蔬菜和全谷類為主的日常飲食能夠降低甘油三酸酯和膽固醇水平，從而降低患心臟病的風(fēng)險?！蹦懝檀际且环N只存在于動物制品中的脂肪物質(zhì)，會在血管系統(tǒng)中堆積，引起血管堵塞，從而導(dǎo)致心臟病發(fā)作或中風(fēng)。像豆腐、豆豉這樣富含植物蛋白的食物中不含膽固醇。不吃動物制品可以避免在日常飲食中攝入膽固醇，從而降低患心臟病的風(fēng)險。

此外，由于大多數(shù)水果和蔬菜的鈉含量不高，純素食的鈉攝入量比其他飲食習(xí)慣更低。鈉會使血壓升高，所以少吃鹽和鈉也更加有益于心血管健康。

血糖控制改善

由于引發(fā)糖尿病的一大危險因素是超重或肥胖，所以減肥能夠降低患糖尿病的風(fēng)險。例如，2018年《營養(yǎng)學(xué)》雜志上發(fā)表了一篇研究論文：在無糖尿病史的超重人群改吃純素食后，研究人員對他們進行了為期16周的跟蹤調(diào)查。研究發(fā)現(xiàn)，這群人的胰島素敏感性上升，負責(zé)生產(chǎn)和釋放胰島素的胰腺細胞功能加強，血糖水平從而得到了改善。

關(guān)節(jié)痛緩解

水果和蔬菜中含有某些叫作植物營養(yǎng)素的化合物，能夠?qū)辜毎l(fā)炎。這些化合物又叫抗氧化物，能夠幫助減輕關(guān)節(jié)炎和其他慢性關(guān)節(jié)病引起的關(guān)節(jié)疼痛、腫脹和壓痛。

除此之外，如果超重，減肥能夠幫助隱隱作痛的下肢關(guān)節(jié)減輕受力。臀部、膝蓋和腳踝承受著整個身體的重量，體重減輕則意味著受力減輕，有時候能夠為患炎癥的關(guān)節(jié)減輕很大受力。

腸道健康改善

由于健康的純素食飲食強調(diào)吃水果、蔬菜和全谷類等高纖維食物，因而能夠幫助改善腸道健康，增強腸道規(guī)律性。

高纖維、全谷類食物中含有益生元，它是一種不可消化的天然化合物，能夠促進腸道中有益細菌的生長。也就是說，你需要益生元來產(chǎn)生益生菌，即那些有益細菌。

攝入的益生元和益生菌達到足夠數(shù)量時，它們就能幫助調(diào)節(jié)腸道健康。越來越多的科學(xué)研究發(fā)現(xiàn)，這有益于整個機體的健康。高纖維食物還能增加糞便體積，從而促進規(guī)律排便，改善胃腸健康。

癌癥風(fēng)險降低

普羅克特說，吃純素食還有可能降低患癌的風(fēng)險。“在搭配合理的純素食飲食中，水果、蔬菜和全谷類的占比也很高。經(jīng)證實，這些植物性食物由于富含抗氧化物和植物營養(yǎng)素，能夠降低患癌的風(fēng)險。”

保證營養(yǎng)均衡

普羅克特表示，確保攝入充足的特定營養(yǎng)素非常重要，這對嚴格的純素食者來說也許更難做到。

“‘純素食’一詞與益于健康并不等同?！逼樟_克特提醒，比如“你可以吃一塊全素餅干，但歸根結(jié)底它仍然只是一塊餅干”。

就像其他任何一種飲食習(xí)慣一樣，應(yīng)該始終注意盡可能吃天然、新鮮的食物。對于經(jīng)過制作或加工的食物，要閱讀其標(biāo)貼，知道自己吃的是什么。

同時，錢皮恩建議，純素食生活方式的轉(zhuǎn)變要慢慢進行?！皬拿坎统詣游镏破返酵蝗灰豢诓怀詴屓朔浅２贿m應(yīng)。要給自己時間尋找菜譜，制訂方案。”

普羅克特還建議“把含蛋白質(zhì)食物混在一起吃，從而保證各類蛋白質(zhì)攝入全面”。例如，大米和豆子一起吃，或者花生醬和果醬抹在全麥面包上一起吃，這能夠為身體全面補充氨基酸，保持肌肉強壯。

同樣，可注意添加豆腐、豆豉、毛豆、豆奶和烘焙黃豆等豆類食物，來保證充足的蛋白質(zhì)攝入。

你還需要確保自己攝入了充足的維生素B12。這對純素食者來說可能是個問題，因為維生素B12“只存在于動物蛋白中”，普羅克特解釋說，“維生素B12對于紅細胞的生成、DNA和RNA的合成，以及保持神經(jīng)系統(tǒng)健康都具有重要意義?！?/p>

（譯者為“《英語世界》杯”翻譯大賽獲獎?wù)撸?/p>

1 tempeh（用酒霉菌使之發(fā)酵后食用的）印尼豆豉。? 2 body composition食品科學(xué)技術(shù)名詞，指人體總重量中，不同身體成分的構(gòu)成比例。

3 cholesterol膽固醇。

4 insulin胰島素。? 5 pancreatic胰的。? 6 phytonutrient植物營養(yǎng)素（一些植物中含有的有助于身體健康和預(yù)防疾病的物質(zhì)）。? 7 antioxidant抗氧化物質(zhì)。

8 gastrointestinal胃腸的。

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