Understanding Soy Safety
豆制品的安全性
作者:Konstanin Yakimchuk
译者:周军
Soy products contain compounds called phytoestrogens, which provide a wealth of health benefits—and a few potential risks。
豆制品中的植物雌激素是一种对人体十分有益的物质,但同时又存在一些潜在的风险。
The growing popularity of soy products in U.S。 and European diets has raised considerable controversy。 While the soy-rich diets of Asia generate documented health benefits, questions persist about the safety of soy in some products, especially infant formula。
美国和欧洲饮食中豆制品的日益普及引起了很大争议。尽管亚洲富含大豆的饮食对健康有益,但一些产品,尤其是婴儿配方奶粉中大豆的安全性仍存在疑问。
To make sense of this debate, it helps to understand the nature of dietary compounds called phytoestrogens—plant-based compounds whose chemical structure resembles estrogens, the female sex hormones of mammals。 Also called isoflavones, phytoestrogens are most prevalent in soybeans and red clover。
为了寻找答案,我们需要了解什么是植物雌激素(Phytoestrogens),它的化学结构类似于雌激素——哺乳动物雌性激素。该激素也称为异黄酮(Isoflavones),在大豆和红三叶草中最为普遍。
Phytoestrogens have been linked to better heart health and reduced risk of breast and prostate cancers。 They can help with osteoporosis and menopausal symptoms and may possibly improve cognitive functions。 For all these benefits, however, the question of whether we should consume more soy-based products or add soy supplements to our diets has not been fully resolved。
植物雌激素有利于心脏健康,并能降低乳腺癌和前列腺癌的罹患风险。可以缓解骨质疏松和更年期症状的作用,还能提高认知能力。而饮食中是否需要更多的豆制品或豆类补品的问题还有待研究。
Let’s walk through the fundamentals of the phytoestrogens at the root of the soy-safety debate。
豆制品安全争议的根源在于植物雌激素的作用原理,我们就从这里入手。
Phytoestrogens in Asian Versus Western Diets
亚洲与西方饮食中的植物雌激素
Soy food, the main source of phytoestrogens, is common in Asian diets but rare in Western cuisine。 Why does consumption vary so much? Different agricultural traditions and dietary preferences are potential answers。
豆制品是植物雌激素的主要来源,在亚洲饮食中很常见,但在西方饮食中却很少。为什么饮食差异如此之大呢?这是由于不同的农业传统和饮食偏好造成的。
People following a traditional Asian diet eat about 15–50 milligrams of isoflavones daily, much more than in the U.S。 and Europe, where less than 2 mg daily is typical (Eisenbrand 2007)。 Asian cuisine uses primarily the first generation of soy products, such as tofu, soybeans and soymilk, while soy-based meat alternatives prevail in the Western diet。
亚洲人每天摄入约15~20毫克的异黄酮,而美国人和欧洲人的日均摄入量则少于2毫克(Eisenbrand 2007),远远低于亚洲人。亚洲饮食以初级加工豆制品为主,如豆腐、大豆和豆浆,而西方则以豆制素肉为主。
The processing of soy products varies in Asian cultures: Unfermented soy products, such as soymilk and tofu, are popular in China, while fermented natto and miso are more common in Japan。 Soy sauce prepared by fermentation is also prominent in Asian cuisines。
在亚洲,不同的文化传统拥有不同的豆制品加工方法:在中国,未发酵的豆制品最为普遍,如豆腐和豆浆;而日本则流行发酵后的纳豆和味噌。发酵而制的酱油在亚洲饮食中也很常见。
In addition to soy, several other plant species grown in the U.S。 are rich in phytoestrogens。 Groundnut, or potato bean—an essential staple in diets of Eastern Native Americans and later the Pilgrims—has the highest content of isoflavones among these species (Zaheer & Humayoun Akhtar 2017)。
除大豆外,美国的其他几种植物也富含植物雌激素。落花生,或马铃薯豆,是东部美洲原住民和后来清教徒必不可少的主食——这些食物中异黄酮的含量最高(Zaheer & Humayoun Akhtar 2017)。
(Editor’s note: The name “groundnut” is used for various plants with edible parts。 The scientific name for potato bean is Apois americana。 )。
(编者注:“落花生”这个名称是指各种带有可食用部分的植物。马铃薯豆的学名是Apois americana。)
Effects on Inflammation and Metabolic Diseases
对炎症和代谢疾病的影响
Experimental data show that phytoestrogens—including genistein, one of the main soy isoflavones—may be useful for treating inflammation, one of the basic mechanisms of metabolic syndrome, athero—sclerosis, arthritis, obesity and diabetes (Yu et al。 2016)。 In particular, phytoestrogens function as antioxidants and may be superior to vitamins C and E (Sierens et al。 2001)。 Just two servings of soy foods can increase blood flow in heart vessels and improve the health of heart muscle。 Phytoestrogens also widen blood vessels, reduce blood pressure, decrease blood cholesterol levels and prevent atherosclerosis in blood vessels (Rietjens, Louisse & Beekmann 2017)。 Note, however, that these plant hormones can suppress the human immune system, which could pose risks (Masilamani, Wei & Sampson 2012)。
实验表明,植物雌激素,包括金雀异黄酮(Genistein,一种主要的大豆异黄酮),可用于治疗炎症。而炎症是代谢疾病、动脉粥样硬化、关节炎、肥胖症和糖尿病的基本机制之一(Yu et al.2016)。特别是其拥有的抗氧化的作用,可能比维生素C和维生素E更好 (Yu et al。 2016)。进食两餐的豆制食物就可以增加心脏血管血流量,促进心肌健康。植物雌激素还可以扩张血管,降低血压,降低血胆固醇并预防动脉粥样硬化(Rietjens, Louisse & Beekmann 2017)。但需要注意的是,这种植物激素会抑制人体免疫系统,造成一定的风险(Masilamani, Wei & Sampson 2012)。
Diabetic patients can benefit from consuming plant estrogens。 Studies performed in the U.S。 and Asia have found an inverse association between consumption of a large variety of soy products and risk of type 2 diabetes (Li et al。 2018)。 Genistein normalizes glucose parameters in peripheral blood, indicating that this isoflavone may increase insulin levels。
植物雌激素对糖尿病患者有益。美国和亚洲的研究发现,食用大量豆制品与患Ⅱ型糖尿病的风险呈负相关(Li et al。 2018)。金雀异黄酮能使外周血液的葡萄糖指标正常化,这说明该异黄酮可能增加胰岛素水平。
Plant Estrogens for Postmenopausal Women
植物雌激素对绝经后女性的影响
Researchers have found that supplementing diets with 30 mg of genistein daily can suppress osteoporosis in postmenopausal women。 That dosage mirrors the regular intake of isoflavones in the traditional Eastern diet。 Moreover, several studies suggest that isoflavones may reduce hot flashes and other postmenopausal symptoms (Messina 2014)。
研究发现,每天补充30毫克金雀异黄酮可以预防绝经后骨质疏松症。该剂量恰为传统东方饮食中异黄酮的常规摄入量。另外,一些研究表明,异黄酮还可能会减轻热潮红和其他绝经后症状(Messina 2014)。
Societies with high consumption of soy foods or isoflavones also see a lower prevalence of breast cancer and other hormone-regulated cancers (Rietjens, Louisse & Beekmann 2017)。 Epidemiologists have noted a reduction in postmenopausal breast cancer even in women consuming moderate amounts of soy (Anderson et al。 2013)。 Phytoestrogen consumption before menopause has also been linked with protection against breast cancer (Lee et al。 2009)。 In clinical studies, patients diagnosed with breast tumors who proceeded with soy intake had a lower rate of recurrence than patients without soy in their diet。 Further, soy food intake has been found to strengthen existing anti-tumor therapies, such as tamoxifen or aromatase inhibitors (Kang et al。 2010)。 Phytoestrogens provide better protection if they are consumed during the teen years or earlier in childhood (Badger et al。 2002; Korde et al。 2009), and there’s some suggestion that consuming soy formula may have a preventive effect against breast tumors (Boucher et al。 2008), though more research is needed。
摄入豆制品和异黄酮较多的人,乳腺癌和一些激素调节型癌症的发病几率较低(Rietjens, Louisse & Beekmann 2017)。有关专家已注意到,摄入适当的豆制品能有效的降低女性绝经后乳腺癌的患病率(Anderson et al。 2013)。女性在绝经前摄入植物雌激素也能有预防乳腺癌的作用(Lee et al.2009)。在乳腺癌患者中,常食用豆制品的患者比不食用豆制品的患者复发病率更低。此外,食用豆制品能有效地加强抗肿瘤疗法,如他莫昔芬(Tamoxifen)和芳香酶抑制剂(Aromatase Inhibitors)(Kang et al,2010)。若在青少年期或儿童期摄入植物雌激素,则有更好的预防效果(Badger et al.2002; Korde et al.2009),还有人提出食用豆奶粉也可能对乳腺癌有预防作用(Boucher et al。 2008),但这需要进一步的研究。
The accumulated data raise the question of whether phytoestrogens could be used for prevention and supplementary therapy of hormone-regulated malignancies。 However, some studies have reported an increase in abnormal growth of breast tissue after short-term intake of isoflavones (Rice & Whitehead 2006)。 Thus, the benefits of soy in women’s diets must be weighed against its potential risks。
有人提出,植物雌激素是否可用于激素调节恶性肿瘤的预防和补充治疗的问题。然而,一些研究表明短期摄入异黄酮后乳房组织异常生长增加(Rice&Whitehead 2006)。因此,必须权衡大豆在女性饮食中的益处与其潜在风险。
Phytoestrogens for Skin Health
植物雌激素对皮肤健康的影响
Phytoestrogens can also influence the health of the skin。 For instance, acne results when overproduction of testosterone activates the sebaceous glands。 Since isoflavones decrease testosterone’s effects, teenagers worrying about acne might consider adding soy foods to their diet。
植物雌激素也会影响皮肤健康。例如,当睾酮过量激活了皮脂腺时就会产生痤疮。但异黄酮具有降低睾酮的作用,所以青少年可在他们的饮食中加入豆制食品预防痤疮。
Natural aging of facial skin reduces elasticity and moisture, leading to wrinkles。 Consuming isoflavones can reduce these age-mediated skin changes。 One study found that daily consumption of 40 mg of aglycone, a phytoestrogen, improved wrinkles and skin plasticity in middle-aged women (Izumi et al。 2007)。 And equol, a phytoestrogen in white cabbage, was shown to decrease facial wrinkles when taken as a dietary supplement (Oyama et al。 2012)。
面部皮肤的老化会降低其弹性和水分,产生皱纹。异黄酮还具有预防皮肤自然老化的作用。研究发现,每天食用40毫克糖苷配基(Aglycone一种植物雌激素),可减少中年女性的皱纹,增强其皮肤可塑性(Izumi et al。 2007)。白菜中的雌马酚(Equol)也是植物雌激素,亦具有减少面部皱纹的作用(Oyama et al。 2012)。
The gamut of potential anti-aging actions of phytoestrogens on the skin includes antioxidative effects, stimulation of collagen and elastin, growth of blood vessels, and increased skin repair and regeneration (Irrera et al。 2017)。 Furthermore, androgen-dependent baldness may potentially be prevented or at least slowed by isoflavones (McElwee et al。 2003)。
植物雌激素有帮助皮肤抗衰老的作用,其中包括抗氧化、促进胶原蛋白和弹性蛋白的生成、促进血管生长以及加强皮肤的修复和再生(Irrera et al。 2017)。此外,异黄酮有预防或缓解雄激素性脱发的作用。
Phytoestrogens and Men’s Health
植物雌激素与男性健康
Phytoestrogens also improve men’s health in several ways。 Consider the impact on prostate cancer, the second-leading cause of cancer deaths in U.S。 men。 Notably, Asian populations with a high intake of soy are less affected by prostate cancer。 Moreover, multiple studies in Asia, the U.S。 and Europe have found that regular consumption of soy products decreases the risk of prostate cancer (Applegate et al。 2018)。 Intake of isoflavones extracted from red clover has been linked to prostate cancer cell death by the process known as apoptosis (Reiter, Gerster & Jungbauer 2011)。
植物雌激素也能从多个方面促进男性健康。前列腺癌是美国男性癌症死亡的第二大原因。值得注意的是,多食用豆制品的亚洲人受前列腺癌的影响较小。亚洲、美国和欧洲的研究发现,经常食用大豆制品可降低患前列腺癌的风险(Applegate et al。 2018)。从红三叶草中提取异黄酮的摄入与前列腺癌细胞的死亡有关,这个过程称为凋亡(Reiter, Gerster & Jungbauer 2011)。
Cognitive and Mental Health Effects
植物雌激素对认知和心理健康的影响
Phytoestrogens often seem to mimic the physiological health effects of estrogens。 Just as estrogens are known to improve cognitive functions in women, phytoestrogens have been shown to assist healthy aging by retaining cognitive performance。 Daily food supplementation with 200 mg of resveratrol, a phytoestrogen in grapes and peanuts, improved memory, reasoning and problem-solving in postmenopausal women, according to Australian researchers (Thaung Zaw, Howe & Wong 2017)。
植物雌激素对生理健康的影响与雌激素类似。雌激素可改善女性的认知功能,与之类似,植物雌激素也可通过保持认知能力促进老年健康。澳大利亚有研究表明,每日通过葡萄和花生等食物补充200毫克的白藜芦醇(Resveratrol,一种植物雌激素),能有效提高绝经后女性的记忆力、推理和解决问题的能力(Thaung Zaw, Howe & Wong 2017)。
Equol, the isoflavone in white cabbage, significantly improves cognitive capacities in elderly individuals (Igase et al。 2017)。 Scientists believe that phytoestrogens stimulate cognitive performance by elevating blood flow in the brain (Evans, Howe & Wong 2017)。
白菜中的异黄酮—雌马酚,能显著提高老年人的认知力(Igase et al。 2017)。科学家认为,植物雌激素是通过促进大脑血液循环来提高认知能力的(Evans, Howe & Wong 2017)。
Depression may be another therapeutic target for dietary estrogens。 Interestingly, the risk of developing depression is higher in women than in men, which implicates sexual hormones in this process。 With regard to menopause, depression is a rather early feature, occurring even sooner than hot flashes。 Phytoestrogens may be able to mend the symptoms of depression, since the chemical structure of soy-derived isoflavones is quite similar to the structure of synthetic drugs used to treat depressive disorders。
食物中的植物雌激素或能治疗抑郁症。有趣的是,女性患抑郁症的风险高于男性,这可以体现性激素在其中的作用。抑郁症是更年期较早的症状,甚至比热潮红更早发生。大豆中的异黄酮与用于治疗抑郁症的合成药物的化学结构非常相似,所以植物雌激素可能对抑郁症有治疗作用。
To evaluate the potential benefits of plant estrogens, clinicians from the Americas, Asia and Europe have performed more than 20 clinical trials in which patients with depression received different doses of isoflavone supplements。 Overall, many of those studies have shown a significant decline in depressive symptoms。 Moreover, isoflavones build on the effects of antidepressants by improving the emotional state of patients。
为了证明植物雌激素对抑郁症的作用,美国、亚洲和欧洲的医生进行了20多项临床试验。抑郁症患者接受了不同剂量的异黄酮,大多数研究结果表明抑郁症得到了抑制。此外,异黄酮还能通过改善患者的情绪来起到抗抑郁药的作用。
Is Soy Safe for Children?
儿童食用豆制品安全吗?
Is it natural and healthy to feed soymilk to infants? Pediatricians worry that the estrogenic activity of phytoestrogens may affect child development。 Infant formula containing soy was introduced in the U.S。 in 1909。 At that time, soy formula was suggested as a substitute for children who could not tolerate cow’s milk。 Nowadays, normal infant formula can be replaced by soy-based formula in cases of allergies, inability to digest milk or when parents want to avoid feeding animal milk to their children。
给婴儿喂豆浆是否自然又健康?儿科医生担心植物雌激素的激素活性可能会影响儿童的生长发育。1909年美国引入了含有大豆配方的婴儿奶粉。当时,大豆配方奶粉是乳糖不耐受儿童的替代食物。如今,在过敏、乳糖不耐受或父母不希望给孩子喂食动物奶的情况下,可以用大豆奶粉代替普通婴儿配方奶粉。
Soy formula is rich in isoflavones, with about 40 mg of plant estrogens per liter。 In contrast, isoflavone concentration in human breast milk is only about 5 micrograms per liter (Setchell et al。 1998)。 Infants who regularly drink soy formula are consuming approximately 10 times more isoflavones than adults on a high-soy diet (Badger et al。 2002; Mortensen et al。 2009)。
大豆奶粉含有丰富的异黄酮,每升含有约40毫克植物雌激素。相比之下,母乳中的异黄酮浓度仅为约5微克每升(Setchell et al。 1998)。经常饮用大豆奶粉的婴儿摄入的异黄酮量大约是成人的10倍(Badger et al.2002; Mortensen et al.2009)。
Though no particular health disturbances have been documented in infants consuming soymilk, according to the National Institute of Environmental Health Sciences (NIEHS 2018), toddlers may be more susceptible to estrogens than grownups are。 Pediatricians are mainly concerned about the potential effects of phytoestrogens on cognitive and sexual development, immunity, and endocrine organs。 However, numerous epidemiological studies have found no significant evidence of developmental, reproductive or endocrine disorders associated with soy formula intake (Vandenplas et al。 2014)。
根据美国国家环境健康科学研究所(NIEHS 2018)的报告,在使用豆奶的婴儿中没有发现特别的健康问题,但婴儿可能比成年人更容易受到雌激素的影响。儿科医生主要关注植物雌激素对认知、性发育、免疫和内分泌器官的潜在影响。然而,许多流行病学研究并未发现摄入大豆奶粉对发育、生殖或内分泌有不良影响。
Epidemiological studies have not confirmed a hypothesis about early puberty in children fed with soy formula。 Studies on neurological development generated similar results: Teenagers showed no differences in behavior, learning capacities or emotional status whether they were fed soy formula or breastfed when they were infants。
流行病学研究尚未证明喂养大豆奶粉与儿童性早熟有关。神经系统发育的研究也产生了类似的结果:无论是喂养豆奶粉还是母乳,青少年在行为、学习能力或情绪状态方面并没有差异。
Precautions: Clouds on the Horizon
预防:未雨绸缪
No matter how promising some recent studies may sound, scientists admonish dietitians and medical doctors not to recklessly prescribe isoflavone supplementation。 The potential effects of plant hormones on male and female reproductive systems are not fully understood (Bennetau-Pelissero 2016)。 Excessive soy intake may cause an imbalance in the menstrual cycle, and several studies have associated decreased sperm count and erectile dysfunction with high intake of soy products。
无论最近关于植物雌激素的研究有多么欣欣向荣,科学家们还是建议营养师和医生不要肆无忌惮地开异黄酮处方。目前,植物激素对人生殖系统的潜在影响尚不完全清楚(Bennetau-Pelissero 2016)。大豆摄入过量可能导致月经失调。还有研究表明,大豆产品摄入量过高会导致精子数量减少和勃起功能障碍。
Furthermore, phytoestrogens may also influence other endocrine systems—inhibiting the effects of thyroid hormones, in particular。 Soy protein is also one of the main triggers of food allergies。
此外,植物雌激素还会影响其他内分泌系统——尤其是抑制甲状腺激素作用。大豆蛋白也是食物过敏的主要诱因之一。
What’s Next for Phytoestrogens
植物雌激素的未来
Many scientists agree that the data on health benefits of soy-derived isoflavones suggest potential preventive and therapeutic applications。 However, what’s the next step?
许多科学家认为,大豆异黄酮有益健康的数据表明了其潜在的预防和治疗作用。但是,下一步是什么?
One obvious path would be to determine which populations might best profit from isoflavone supplementation。 For instance, communities with a high frequency of lactose intolerance could be target groups for including soy-derived products in the regular diet。 Detailed knowledge of the family history of specific disorders might influence decisions on whether to recommend soy formula in every case。 And with regard to soy food production, new processing methods might be required to create foods with a higher phytoestrogen content。
首先,应确定大豆异黄酮对哪些人群最有益处。例如,乳糖不耐受患者应该在其常规饮食中加入豆制品。在食用豆奶粉之前,应该了解家族病史。另外,可能需要更好的加工方法来制造具有更高植物雌激素含量的产品。
One more thing to remember: Despite all the healthy optimism in the scientific community, phytoestrogens should be valued and used with caution。 More studies are needed before we can solve the puzzle of phytoestrogens。
切记:尽管科学界对植物雌激素持乐观态度,但我们应该谨慎使用它。关于植物雌激素的诸多问题,还需要进一步研究。
WHAT IS A PHYTOESTROGEN?
什么是植物雌激素?
Phytoestrogens are chemical compounds common in soy-based foods。 Their chemical structure is similar to that of estrogen, the mammalian sex hormone。
植物雌激素是豆类食品中常见的化合物,它们的化学结构类似于雌激素(哺乳动物性激素)。
Phytoestrogens have been linked to a host of health benefits。 Among them:
- reduced risk of breast and prostate cancer
- easing of osteoporosis and menopausal symptoms
- improved cognitive function
- healthier skin with fewer wrinkles
植物雌激素对健康有很多益处:
•降低患乳腺癌和前列腺癌的风险
•缓解骨质疏松症和更年期症状
•改善认知能力
•使皮肤更健康,皱纹更少
Risks of phytoestrogens include the following:
- potential declines of immune function
- infertility and erectile dysfunction in men
植物雌激素的不良影响:
•潜在的免疫功能下降
•男性不育和勃起功能障碍
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