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吃素食在营养健康上会有很多优势，但也有很多挑战。

有证据表明，素食者一般更加健康和长寿。素食者患冠心病，肥胖症，高血压，II型糖尿病和某些癌症的比例较低。素食往往富含碳水化合物，Ω-6脂肪酸，膳食纤维，胡萝卜素，叶酸，维生素C，维生素E，钾和镁。素食中饱和脂肪，胆固醇及动物性蛋白质的含量普遍较低^[1]。

不过，素食饮食有时可能会相对缺乏的蛋白质，铁，锌，维生素B₁₂，钙和其他营养物质^[2]。尽管如此，精心设计的素食和全素食菜谱能够满足所有这些营养需求，可以适应人生命中的各个阶段，包括怀孕期，哺乳期，婴儿期，儿童期和青春期。

素食的益处

素食通常富含碳水化合物，Ω-6脂肪酸，膳食纤维，胡萝卜素，叶酸，维生素C，维生素E，钾和镁。但素食中饱和和脂肪，胆固醇及动物蛋白质的含量较低。

有证据表明，素食者的健康程度与非素食者相比毫不逊色^[3]。在英国，素食者比非素食者死亡率更低，虽然这可能是由于膳食之外的因素，如素食者中吸烟者较少或者一般具有较高社会经济地位，或者由于食谱中除了避免肉类和鱼类意外其他方面的因素。最值得注意的是，素食避免了对健康有众多负面影响的红肉^[4]。

调查发现，素食者比非素食者由冠心病引起的死亡率低24%。癌症研究表明，大量的红肉和癌症之间有着明显的联系。有证据表明，素食者往往体重指数(BMI)较低^[5]，肥胖症和高血胆固醇风险较小，同型半胱氨酸水平较低，而且患高血压和II型糖尿病的风险较小。还有一个大型的前瞻性研究发现，非肉食者比肉食者需要紧急阑尾切除术的几率低了一半。

潜在的营养不足

不善计划素食食谱可以会缺乏蛋白质，铁，锌，维生素B₁₂，钙，Ω-3脂肪酸，维生素A，维生素D，核黄素（维生素B2）和碘。全素食者更有可能缺乏维生素B₁₂和钙。尽管如此，均衡的素食和全素食食谱能满足所有这些营养需求，并适应人生命中的各个阶段，包括怀孕期，哺乳期，婴儿期，童年期和青春期^[6]^[7]。

蛋白质

只要卡路里摄入量足够，饮食种类丰富，一般的素食能够获得足够所需的蛋白质^[8]。素食中蛋白质含量一般较低，这有可能是有益的^[9]^[10]^[11]^[12]^[13]^[14]^[15]。

蛋白质的合成

“几乎所有的植物性食品中都包含所有的必需氨基酸；不仅是包含，而且含量足够满足正常的成年人，如果您的饮食中包含足够的卡路里的话。”
——基思.阿科尔斯

尽管人们普遍认为，素食者必须在不超过几个小时内食用谷类和豆类，才能“合成”包含全部九种“必需氨基酸 ”的蛋白质，然而这种说法还从来没有被研究证实过。由于弗朗西斯.穆尔.拉佩1971年的畅销书《一个小星球的饮食》(Diet for a Small Planet)，蛋白质相合成理论受到广泛关注。在此书1981年以后的版本中，拉佩删除了蛋白质“合成”必要性的争论^[16]。

铁

肉类，鱼类和家禽是血红素铁的唯一来源，植物中只包含非血红素铁，其人体吸收效果相对较差^[17]^[18]^[19]^[20]。但是，谷类，蛋，豆类（包括豌豆，大豆，鹰嘴豆，小扁豆及豆豉）和坚果都是铁的重要来源，因此精心策划的素食不会引起缺铁^[21]。

刊登在美国饮食协会会刊上的一项研究发现，虽然缺铁性贫血在素食者中并不是更加常见，由于“缺乏高吸收率动物铁的来源”，“素食儿童...与非素食者相比，血红蛋白和铁的水平较低”。

锌

西方的素食和全素食者中没有发现比肉食者更多的锌缺乏症^[22]。但是，许多全谷类中的植酸和许多食品中的和纤维可能会干扰锌的吸收，而对锌摄入量过少的影响研究还十分有限。

维生素B₁₂

缺乏维生素B₁₂的后果可能极其严重，导致恶性贫血，神经变性和不可逆的神经损害。定期摄入维生素B₁₂对年龄超过五十的人，孕妇和哺乳期妇女（包括母乳喂养的婴儿，如果母亲的饮食中不充足的话）是格外重要的。

有证据表明，不食用维生素B₁₂补充剂或B₁₂强化食品的素食者和全素食者，其B₁₂摄入量不足，而且往往血液中维生素B₁₂浓度过低^[23]^[24]^[25]。这是因为，除非人工添加，植物性食品中不包含足够有效的维生素B₁₂。

因此，对素食者来说，一定要摄入有足够的乳制品，鸡蛋，营养补充剂或人工维生素B₁₂强化食品（包括某些酵母提取物，大豆，牛奶，蔬菜和葵花黄油，以及和谷类早餐等）^[26]。

紫菜（海藻）中包含大量的维生素B₁₂。但植物来源的维生素B₁₂（或类似物）尚不能被人类利用^[27]。有一项栽培法的专利，能够通过菌丝体丰富蔬菜中的维生素B₁₂^[28]。

Ω-3脂肪酸

Ω-3脂肪酸的素食来源包括亚麻籽和亚麻籽油，橄榄油，核桃，油菜油，鳄梨和鸡蛋。

素食来源的Ω-3脂肪酸主要是短链类的，并可能其中两种必需脂肪酸（EFA）的浓度较低，即二十碳五烯酸（EPA）和二十二碳六烯酸（DHA）。人体可以通过其他Ω-3脂肪酸，如α-亚麻酸（包含在素食Ω-3脂肪酸中）合成少量的EPA和DHA。人体还可以将DHA转换成EPA。可以买到提取自富含DHA的藻类的DHA补充剂。人体虽然可以在理论上完成这种转换，然而在实践中，现代饮食和生活方式减少了转换系统的有效性^[29]。为了达到与来自鱼油的长链 Ω-3同样的效果，必须摄入近十倍以上的短链Ω-3。

虽然Ω-3脂肪酸的作用还没有科学上的共识，一般认为，它能够减少冠心病风险，降低三酸甘油脂，稳定的情绪和预防抑郁症，有助于减轻多动症症状，减轻关节痛和其他类风湿的问题，还能减少老年人患痴呆症的危险^[30]。

维生素D

当皮肤暴露于太阳紫外线辐射中时，人体可以合成维生素D。全素食者如果既不吃添加合成维生素D的食品或药丸，又很少暴露于太阳紫外线辐射中（例如，每天四肢接触阳光时间少于15-30分钟，或者居住在高纬度地区），那就容易缺乏维生素D。

维生素D作为激素，发送信号到肠道，增加对钙和磷的吸收，以产生强壮的骨骼。维生素D也与若干其他维生素，矿物质及雌激素合作，促进骨骼矿化。研究还表明，维生素D可能有助于保持一个健康的免疫系统，并帮助调节细胞的生长和分化。

碘

根据不列颠营养杂志，“在严格的素食饮食中存在潜在的碘缺乏症的危险，尤其是当水果和蔬菜生长在低碘土壤中时^[31]。”不过，在许多国家中，通常可以从加碘食盐和其他来源中获得碘。此外，应该指出的是，动物体内的任何碘都是来源于植物的。

核黄素（维生素B2）

根据美国饮食协会，“一些研究表明，全素食者维生素B2摄入量与非素食者相比较低；不过，临床上并没有发现核黄素缺乏症。”

参考资料

^ Black, Maureen. Effects of vitamin B12 and folate deficiency on brain development in children. US National Library of Medicine National Institutes of Health. June 2008, 29 (2 Suppl): S126–31. PMC 3137939 . PMID 18709887.
^ Incidence of osteoporosis in vegetarians and omnivores (PDF). Ajcn.org. [2017-09-04]. （原始内容存档 (PDF)于2010-10-02）.
^ Appleby, Paul N; Thorogood, Margaret; Mann, Jim I; Key, Timothy JA. The Oxford Vegetarian Study: An overview. The American Journal of Clinical Nutrition. 1999, 70 (3 Suppl): 525S–531S [2017-03-10]. PMID 10479226. （原始内容存档于2015-01-18）.
^ Appleby, Paul N; Key, Timothy J; Thorogood, Margaret; Burr, Michael L; Mann, Jim. Mortality in British vegetarians. Public Health Nutrition. 2007, 5 (1): 29–36. PMID 12001975. doi:10.1079/PHN2001248.
^ American Dietetic, Association; Dietitians Of, Canada. Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets. Journal of the American Dietetic Association. 2003, 103 (6): 748–65. PMID 12778049. doi:10.1053/jada.2003.50142.
^ Loma Linda University Vegetarian Food Pyramid 互联网档案馆的存檔，存档日期2011-07-28.
^ Messina, Virginia; Melina, Vesanto; Mangels, Ann Reed. A new food guide for North American vegetarians. Canadian Journal of Dietetic Practice and Research: A Publication of Dietitians of Canada = Revue Canadienne De La Pratique Et De La Recherche En Dietetique: Une Publication Des Dietetistes Du Canada. 2003-01-01, 64 (2): 82–86. ISSN 1486-3847. PMID 12826029. doi:10.3148/64.2.2003.82. （原始内容存档于2007-03-01）.
^ Akers, Keith: But How Do You Get Enough Protein? 互联网档案馆的存檔，存档日期2010-10-28.. Compassionate Spirit. Retrieved 25 June 2010.^{[不可靠的醫學來源？]}
^ Fontana, L; Klein, S; Holloszy, J. O. Long-term low-protein, low-calorie diet and endurance exercise modulate metabolic factors associated with cancer risk. The American Journal of Clinical Nutrition. 2006, 84 (6): 1456–62. PMID 17158430. 简明摘要 – Nutra Ingredients (December 7, 2006).
^ Diabetic nephropathy. Clinicalevidence.com. [2017-09-04]. （原始内容存档于2020-01-28）（英语）.
^ Feskanich, D; Willett, W C; Stampfer, M J; Colditz, G A. Milk, dietary calcium, and bone fractures in women: A 12-year prospective study. American Journal of Public Health. 1997, 87 (6): 992–7. PMC 1380936 . PMID 9224182. doi:10.2105/AJPH.87.6.992.
^ Feskanich, D; Willett, W. C.; Colditz, G. A. Calcium, vitamin D, milk consumption, and hip fractures: A prospective study among postmenopausal women. The American Journal of Clinical Nutrition. 2003, 77 (2): 504–11. PMID 12540414.
^ Cumming, R. G.; Klineberg, R. J. Case-control study of risk factors for hip fractures in the elderly. American Journal of Epidemiology. 1994, 139 (5): 493–503. PMID 8154473.
^ Grandison, Richard C.; Piper, Matthew D. W.; Partridge, Linda. Amino-acid imbalance explains extension of lifespan by dietary restriction in Drosophila. Nature. 2009, 462 (7276): 1061–4 [2017-03-10]. Bibcode:2009Natur.462.1061G. PMC 2798000 . PMID 19956092. doi:10.1038/nature08619. （原始内容存档于2015-01-10）. 简明摘要 – The Telegraph (December 3, 2009).
^ Craig, Winston J.; Pinyan, Laura. Nutrients of Concern in Vegetarian Diets. Sabate, Joan (编). Vegetarian Nutrition. CRC Press. 2001: 299–332 [2017-03-10]. ISBN 978-1-4200-3683-1. （原始内容存档于2019-09-03）.
^ Lappé, Frances Moore. Diet for a Small Planet. 1981: 162. ISBN 0-345-32120-0.
^ Larsson, C. L.; Johansson, G. K. Dietary intake and nutritional status of young vegans and omnivores in Sweden. The American Journal of Clinical Nutrition. 2002, 76 (1): 100–6 [2017-03-10]. PMID 12081822. （原始内容存档于2016-08-08）.
^ Messina MJ, Messina VL. The Dietitian's Guide to Vegetarian Diets: Issues and Applications. Gaithersburg, MD: Aspen Publishers; 1996.^{[页码请求]}
^ Craig, W. J. Iron status of vegetarians. The American Journal of Clinical Nutrition. 1994, 59 (5 Suppl): 1233S–1237S. PMID 8172127.
^ Ball, M. J.; Bartlett, M. A. Dietary intake and iron status of Australian vegetarian women. The American Journal of Clinical Nutrition. 1999, 70 (3): 353–8. PMID 10479197.
^ Krajcovicová-Kudlácková, M; Simoncic, R; Béderová, A; Grancicová, E; Magálová, T. Influence of vegetarian and mixed nutrition on selected haematological and biochemical parameters in children. Die Nahrung. 1997, 41 (5): 311–4. PMID 9399258. doi:10.1002/food.19970410513.
^ Freeland-Graves, J. H.; Bodzy, P. W.; Eppright, M. A. Zinc status of vegetarians. Journal of the American Dietetic Association. 1980, 77 (6): 655–61. PMID 7440860.
^ Hokin, B. D.; Butler, T. Cyanocobalamin (vitamin B-12) status in Seventh-day Adventist ministers in Australia. The American Journal of Clinical Nutrition. 1999, 70 (3 Suppl): 576S–578S [2017-03-10]. PMID 10479234. （原始内容存档于2016-07-31）.
^ Krajčovičová-Kudláčková, M.; Blažíček, P.; Kopčová, J.; Béderová, A.; Babinská, K. Homocysteine Levels in Vegetarians versus Omnivores. Annals of Nutrition and Metabolism. 2000, 44 (3): 135–8. PMID 11053901. doi:10.1159/000012827.
^ VeganHealth.org: B12 and Chronic Disease: Homocysteine （页面存档备份，存于互联网档案馆）. Retrieved 26 April 2007.
^ The Vegetarian Society. Information Sheet: Vitamin B Template:Ssub 互联网档案馆的存檔，存档日期2008-08-22.. Retrieved 26 April 2007.
^ Mozafar, A. Enrichment of some B-vitamins in plants with application of organic fertilizers. Plant and Soil. 1994, 167 (2): 305–311. doi:10.1007/BF00007957.
^ Seed and plant containing vitamin B12 and method of producing the same. [2017-03-10]. （原始内容存档于2012-02-25）.
^ Sanders, Thomas A.B. DHA status of vegetarians. Prostaglandins, Leukotrienes and Essential Fatty Acids. 2009, 81 (2–3): 137–141. PMID 19500961. doi:10.1016/[j.plefa.2009.05.013.
^ Mezzano, Diego; Kosiel, Karin; Martínez, Carlos; Cuevas, Ada; Panes, Olga; Aranda, Eduardo; Strobel, Pablo; Pérez, Druso D; Pereira, Jaime; et al. Cardiovascular Risk Factors in Vegetarians: Normalization of Hyperhomocysteinemia with Vitamin B₁₂ and Reduction of Platelet Aggregation with n-3 Fatty Acids. Thrombosis Research. 2000, 100 (3): 153–60. PMID 11108902. doi:10.1016/S0049-3848(00)00313-3.
^ Remer, Thomas; Neubert, Annette; Manz, Friedrich. Increased risk of iodine deficiency with vegetarian nutrition. British Journal of Nutrition. 2007, 81 (1): 45–9. PMID 10341675. doi:10.1017/S0007114599000136.

[1] Black, Maureen. Effects of vitamin B12 and folate deficiency on brain development in children. US National Library of Medicine National Institutes of Health. June 2008, 29 (2 Suppl): S126–31. PMC 3137939 . PMID 18709887.

[2] Incidence of osteoporosis in vegetarians and omnivores (PDF). Ajcn.org. [2017-09-04]. （原始内容存档 (PDF)于2010-10-02）.

[appleby2-3] Appleby, Paul N; Thorogood, Margaret; Mann, Jim I; Key, Timothy JA. The Oxford Vegetarian Study: An overview. The American Journal of Clinical Nutrition. 1999, 70 (3 Suppl): 525S–531S [2017-03-10]. PMID 10479226. （原始内容存档于2015-01-18）.

[appleby-4] Appleby, Paul N; Key, Timothy J; Thorogood, Margaret; Burr, Michael L; Mann, Jim. Mortality in British vegetarians. Public Health Nutrition. 2007, 5 (1): 29–36. PMID 12001975. doi:10.1079/PHN2001248.

[ada-5] American Dietetic, Association; Dietitians Of, Canada. Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets. Journal of the American Dietetic Association. 2003, 103 (6): 748–65. PMID 12778049. doi:10.1053/jada.2003.50142.

[6] Loma Linda University Vegetarian Food Pyramid 互联网档案馆的存檔，存档日期2011-07-28.

[7] Messina, Virginia; Melina, Vesanto; Mangels, Ann Reed. A new food guide for North American vegetarians. Canadian Journal of Dietetic Practice and Research: A Publication of Dietitians of Canada = Revue Canadienne De La Pratique Et De La Recherche En Dietetique: Une Publication Des Dietetistes Du Canada. 2003-01-01, 64 (2): 82–86. ISSN 1486-3847. PMID 12826029. doi:10.3148/64.2.2003.82. （原始内容存档于2007-03-01）.

[akers-8] Akers, Keith: But How Do You Get Enough Protein? 互联网档案馆的存檔，存档日期2010-10-28.. Compassionate Spirit. Retrieved 25 June 2010.^{[不可靠的醫學來源？]}

[9] Fontana, L; Klein, S; Holloszy, J. O. Long-term low-protein, low-calorie diet and endurance exercise modulate metabolic factors associated with cancer risk. The American Journal of Clinical Nutrition. 2006, 84 (6): 1456–62. PMID 17158430. 简明摘要 – Nutra Ingredients (December 7, 2006).

[10] Diabetic nephropathy. Clinicalevidence.com. [2017-09-04]. （原始内容存档于2020-01-28）（英语）.

[11] Feskanich, D; Willett, W C; Stampfer, M J; Colditz, G A. Milk, dietary calcium, and bone fractures in women: A 12-year prospective study. American Journal of Public Health. 1997, 87 (6): 992–7. PMC 1380936 . PMID 9224182. doi:10.2105/AJPH.87.6.992.

[12] Feskanich, D; Willett, W. C.; Colditz, G. A. Calcium, vitamin D, milk consumption, and hip fractures: A prospective study among postmenopausal women. The American Journal of Clinical Nutrition. 2003, 77 (2): 504–11. PMID 12540414.

[13] Cumming, R. G.; Klineberg, R. J. Case-control study of risk factors for hip fractures in the elderly. American Journal of Epidemiology. 1994, 139 (5): 493–503. PMID 8154473.

[14] Grandison, Richard C.; Piper, Matthew D. W.; Partridge, Linda. Amino-acid imbalance explains extension of lifespan by dietary restriction in Drosophila. Nature. 2009, 462 (7276): 1061–4 [2017-03-10]. Bibcode:2009Natur.462.1061G. PMC 2798000 . PMID 19956092. doi:10.1038/nature08619. （原始内容存档于2015-01-10）. 简明摘要 – The Telegraph (December 3, 2009).

[15] Craig, Winston J.; Pinyan, Laura. Nutrients of Concern in Vegetarian Diets. Sabate, Joan (编). Vegetarian Nutrition. CRC Press. 2001: 299–332 [2017-03-10]. ISBN 978-1-4200-3683-1. （原始内容存档于2019-09-03）.

[16] Lappé, Frances Moore. Diet for a Small Planet. 1981: 162. ISBN 0-345-32120-0.

[17] Larsson, C. L.; Johansson, G. K. Dietary intake and nutritional status of young vegans and omnivores in Sweden. The American Journal of Clinical Nutrition. 2002, 76 (1): 100–6 [2017-03-10]. PMID 12081822. （原始内容存档于2016-08-08）.

[18] Messina MJ, Messina VL. The Dietitian's Guide to Vegetarian Diets: Issues and Applications. Gaithersburg, MD: Aspen Publishers; 1996.^{[页码请求]}

[19] Craig, W. J. Iron status of vegetarians. The American Journal of Clinical Nutrition. 1994, 59 (5 Suppl): 1233S–1237S. PMID 8172127.

[20] Ball, M. J.; Bartlett, M. A. Dietary intake and iron status of Australian vegetarian women. The American Journal of Clinical Nutrition. 1999, 70 (3): 353–8. PMID 10479197.

[nahrung-21] Krajcovicová-Kudlácková, M; Simoncic, R; Béderová, A; Grancicová, E; Magálová, T. Influence of vegetarian and mixed nutrition on selected haematological and biochemical parameters in children. Die Nahrung. 1997, 41 (5): 311–4. PMID 9399258. doi:10.1002/food.19970410513.

[22] Freeland-Graves, J. H.; Bodzy, P. W.; Eppright, M. A. Zinc status of vegetarians. Journal of the American Dietetic Association. 1980, 77 (6): 655–61. PMID 7440860.

[23] Hokin, B. D.; Butler, T. Cyanocobalamin (vitamin B-12) status in Seventh-day Adventist ministers in Australia. The American Journal of Clinical Nutrition. 1999, 70 (3 Suppl): 576S–578S [2017-03-10]. PMID 10479234. （原始内容存档于2016-07-31）.

[24] Krajčovičová-Kudláčková, M.; Blažíček, P.; Kopčová, J.; Béderová, A.; Babinská, K. Homocysteine Levels in Vegetarians versus Omnivores. Annals of Nutrition and Metabolism. 2000, 44 (3): 135–8. PMID 11053901. doi:10.1159/000012827.

[25] VeganHealth.org: B12 and Chronic Disease: Homocysteine （页面存档备份，存于互联网档案馆）. Retrieved 26 April 2007.

[b12-26] The Vegetarian Society. Information Sheet: Vitamin B Template:Ssub 互联网档案馆的存檔，存档日期2008-08-22.. Retrieved 26 April 2007.

[27] Mozafar, A. Enrichment of some B-vitamins in plants with application of organic fertilizers. Plant and Soil. 1994, 167 (2): 305–311. doi:10.1007/BF00007957.

[28] Seed and plant containing vitamin B12 and method of producing the same. [2017-03-10]. （原始内容存档于2012-02-25）.

[dha-29] Sanders, Thomas A.B. DHA status of vegetarians. Prostaglandins, Leukotrienes and Essential Fatty Acids. 2009, 81 (2–3): 137–141. PMID 19500961. doi:10.1016/[j.plefa.2009.05.013.

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