Vegetarian nutrition
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[[Image:Vegetarian diet.jpg|thumb|right|A variety of vegetarian ingredients]]'''Vegetarian [[nutrition]]''' is the set of health-related challenges and advantages of [[Vegetarianism|vegetarian]] diets.
Evidence suggests that vegetarians are generally healthier and live longer than non-vegetarians. They have lower rates of [[coronary heart disease]], [[obesity]], [[hypertension]], [[type 2 diabetes]] and some forms of [[cancer]]. Vegetarian diets tend to be rich in [[carbohydrates]], [[omega-6 fatty acids]], [[dietary fibre]], [[carotenoids]], [[folic acid]], [[vitamin C]], [[vitamin E]], [[potassium]] and [[magnesium]]. They are generally low in [[saturated fat]], [[cholesterol]], and animal protein.
However, vegetarian diets can sometimes be relatively low in [[protein]], [[iron]], [[zinc]], [[Vitamin B12|vitamin B<sub>12</sub>]], [[calcium]] and other nutrients. Nonetheless, well-planned vegetarian and [[vegan]] diets can meet all these nutrient requirements and are appropriate for all stages of the life cycle, including during pregnancy, lactation, infancy, childhood, and adolescence.
==Benefits of a vegetarian diet==
Vegetarian diets are usually rich in [[carbohydrates]], [[omega-6 fatty acids]], [[dietary fibre]], [[carotenoids]], [[folic acid]], [[vitamin C]], [[vitamin E]], [[potassium]] and [[magnesium]].<ref name="ada"/><ref name="key1">Key TJ, Appleby PN, Rosell MS: [http://www.epic-oxford.org/gen_abstract_314.html “Health effects of vegetarian and vegan diets”]. ''Proceedings of the Nutrition Society'', 2006, 65:35-41. Accessed 4 January 2007.</ref> They contain lower levels of [[saturated fat]], [[cholesterol]], and animal protein.<ref name="ada"/>
Evidence suggests that the health of vegetarians compares favourably with that of non-vegetarians.<ref name="appleby2">Appleby PN, Thorogood M, Mann JI, Key TJ: “[http://www.epic-oxford.org/gen_abstract_39.html The Oxford Vegetarian Study: an overview]”. ''American Journal of Clinical Nutrition'', 1999, 70:525S-531S. Accessed 4 January 2007.</ref> British vegetarians have lower [[Mortality rate|death rates]] than non-vegetarians,<ref name="appleby2"/><ref name="key2">Key TJ, Appleby PN, Davey GK, Allen NE, Spencer EA, Travis RC: [http://www.epic-oxford.org/gen_abstract_4.html “Mortality in British vegetarians: review and preliminary results from EPIC-Oxford”]. ''American Journal of Clinical Nutrition'', 2003, 78:533S-538S. Accessed 4 January 2007.</ref> although this may be due to non-dietary lifestyle factors, such as a low prevalence of smoking and the generally high socio-economic status of vegetarians, or to aspects of the diet other than the avoidance of meat and fish.<ref name="appleby">Appleby PN, Key TJ, Thorogood M, Burr ML, Mann J: [http://www.epic-oxford.org/gen_abstract_41.html “Mortality in British vegetarians”]. ''Public Health Nutrition'', 2002, 5:29-36. Accessed 4 January 2007.</ref> Most notably, a vegetarian diet avoids the multitude of negative [[Red_meat#Health_effects|health effects of red meat]].
One review found that mortality from [[coronary heart disease]] was 24% lower in vegetarians than in nonvegetarians.<ref name="key3">Key TJ, Fraser GE, Thorogood M, Appleby PN, Beral V, Reeves G, Burr ML, Chang-Claude J, Frentzel-Beyme R, Kuzma JW, Mann J, McPherson K: [http://www.epic-oxford.org/gen_abstract_38.html “Mortality in vegetarians and nonvegetarians: detailed findings from a collaborative analysis of 5 prospective studies”]. ''American Journal of Clinical Nutrition'', 1999, 70:516S-524S. Accessed 4 January 2007.</ref> Studies of cancer have shown a clear link between large amounts of [[Red_meat#Cancer|red meat and cancer]]. There is evidence that vegetarians tend to have a lower [[body mass index]],<ref name="ada">[http://www.adajournal.org/article/PIIS0002822303002943/fulltext “Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets”]. ''Journal of the American Dietetic Association'', 2003, 06. Accessed 4 January 2007.</ref><ref name="key1"/> lower risk of [[obesity]],<ref name="aha">[[American Heart Association]]: [http://www.americanheart.org/presenter.jhtml?identifier=4777 ''Vegetarian Diets'']. Accessed 4 January 2007.</ref> lower blood [[cholesterol]] levels,<ref name="ada"/><ref name="key1"/> lower [[homocysteine]] levels,<ref name="key1"/>, lower risk of [[hypertension|high blood pressure]],<ref name="ada"/><ref name="aha"/> and lower risk of [[type 2 diabetes]].<ref name="ada"/><ref name="aha"/> One large [[prospective study]] found that non-meat-eaters had only half the risk of meat eaters of requiring an emergency [[appendectomy]].<ref name="appleby2"/>
==Potential nutrient deficiencies==
Poorly planned vegetarian diets can be relatively low in [[protein]], [[iron]], [[zinc]], [[Vitamin B12|vitamin B<sub>12</sub>]], [[calcium]], [[omega-3 fatty acids]], [[retinol]] ([[vitamin A]]), [[vitamin D]], [[riboflavin]] ([[Vitamin B2|vitamin B<sub>2</sub>]]) and [[iodine]].<ref name="ada"/><ref name="key1"/> Vegans may have particularly low intakes of vitamin B<sub>12</sub> and [[calcium]].<ref name="key1"/> Nonetheless, well-balanced vegetarian and vegan diets can meet all these nutrient requirements and are appropriate for all stages of the life cycle, including during [[pregnancy]], [[lactation]], [[infant|infancy]], [[childhood]], and [[adolescence]].<ref name="ada"/>
=== Protein ===
The typical vegetarian gets adequate [[protein]] as long as caloric intake is adequate and a variety of foods is eaten.<ref name=akers>[[Keith Akers|Akers, Keith]]: ''[http://www.vsc.org/protein.htm But How Do You Get Enough Protein?]''. Vegetarian Society of Colorado. Accessed 11 April 2007.</ref>
Vegetarian diets are usually relatively low in protein,<ref name="key1"/> which may be beneficial.<ref>Food Navigator USA: [http://www.foodnavigator-usa.com/news/ng.asp?n=72611-protein-cancer ''Low-protein diets could protect against cancer, says new study'']. 7 December 2006. Accessed 4 January 2007.</ref><ref>[http://www.clinicalevidence.com/ceweb/conditions/dia/0606/0606_I8.jsp Diabetic nephropathy]</ref>
==== Combining proteins ====
{{main|Protein combining}}{{rquote|right|Virtually all plant foods have ''all'' of the essential amino acids; and not only are the amino acids there, they are present in more than enough quantity to meet the needs of normal adults, if you are on a calorically adequate diet.
— [[Keith Akers]]<ref name=akers/>}}
Despite a widespread belief that vegetarians must eat grains and beans within a few hours of each other in order to make a 'complete' protein which contains all 9 "[[essential amino acid]]s", this has never been substantiated by research. The protein-combining theory was brought to popular attention in [[Frances Moore Lappé]]'s 1971 bestseller ''[[Diet for a Small Planet]]''.<ref name=akers/> In later editions of the book, as early as 1981, Lappé withdrew her contention that protein 'combining' is necessary.<ref>[[Frances Moore Lappé|Lappé, Frances Moore]] (1981). ''[[Diet for a Small Planet]]'', p. 162. ISBN 0-345-32120-0</ref>
=== Iron ===
Meat, fish and poultry are the only sources of [[heme]] [[iron]]; [[plant]]s contain only non-heme iron, which is absorbed less efficiently by the human body.<ref name="nahrung"/> However, cereals, eggs, legumes (including peas, beans, chickpeas, [[lentils]] and soy foods) and nuts are significant sources of iron,<ref>Nutrition Australia: ''[http://www.nutritionaustralia.org/Food_Facts/FAQ/vegetarian_new_detailed_faq.asp FAQ on Vegetarian Diets]''. Accessed 11 April 2007.</ref> so a well planned vegetarian diet should not lead to iron deficiency.
A study in the Journal of the American Dietetic Association found that while iron-deficiency [[anemia]] is not more common among vegetarians, "vegetarian children had ... reduced levels of haemoglobin and iron compared to omnivores" due "to the absence of animal iron sources with high utilizability".<ref name="nahrung">Krajcovicova-Kudlackova M, Simoncic R, Bederova A, Grancicova E, Magalova T: “[http://www.adajournal.org/medline/record/MDLN.9399258 Influence of vegetarian and mixed nutrition on selected haematological and biochemical parameters in children].” ''Nahrung'', October 1997, 41:311-314.</ref>
[[Image:Tofu-beijingchina.jpg|thumb|right|[[Tofu]] can be a valuable source of protein, iron, zinc and calcium for vegetarians and vegans]]
=== Zinc ===
Western vegetarians and vegans have not been found to suffer from overt [[zinc]] deficiencies any more than meat-eaters.<ref>Freeland-Graves J. H., Bodzy P. W., Epright M. A.: “Zinc status of vegetarians”. ''Journal of the American Dietetic Association'', 1980, 77:655-661</ref> However, [[phytate]]s in many whole-grains and fiber in many foods may interfere with zinc absorption and marginal zinc intake has poorly understood effects.<ref name="ada"/>
=== Vitamin B<sub>12</sub> ===
[[Vitamin B12|Vitamin B<sub>12</sub>]] deficiency is potentially extremely serious, leading to [[pernicious anemia]], nerve degeneration and irreversible neurological damage.<ref name=b12/> A regular source of vitamin B<sub>12</sub> is particularly important for those over the age of 50 years, and pregnant and lactating women (and for breastfed infants if the mother's diet is not supplemented).<ref name="ada"/>
Evidence suggests that vegetarians and vegans who are not taking vitamin B<sub>12</sub> supplements or B<sub>12</sub>-fortified foods do not consume sufficient servings of B<sub>12</sub> and often have abnormally low blood concentrations of vitamin B<sub>12</sub>.<ref>See, for example, Hokin BD and Butler T: “[http://www.ajcn.org/cgi/content/full/70/3/576S Cyanocobalamin (vitamin B-12) status in Seventh-day Adventist ministers in Australia]” in ''American Journal of Clinical Nutrition'', September 1999, 70:576S-578S; and Krajcovicova-Kudlackova M, Blazicek P, Kopcova J, Bederova A and Babinska K: “[http://content.karger.com/produktedb/produkte.asp?typ=fulltext&file=anm44135 Homocysteine Levels in Vegetarians versus Omnivores]” in ''Annals of Nutrition & Metabolism'', 2000, 44:135-138; and VeganHealth.org: ''[http://www.veganhealth.org/b12/hcy B12 and Chronic Disease: Homocysteine]''. Accessed 26 April 2007.</ref> This is because, unless fortified, plant foods do not contain significant amounts of active [[Vitamin B12|vitamin B<sub>12</sub>]].<ref name="ada"/>
It is essential, therefore, that vegetarians consume adequate amounts of [[dairy product]]s, eggs, [[dietary supplement]]s or foods that have been fortified with B<sub>12</sub> (such as certain [[yeast extract]]s, vegetable [[stock (food)|stock]], [[veggie burger]] mixes, [[textured vegetable protein]], [[soy milk]]s, vegetable and sunflower [[margarine]]s, and [[breakfast cereal]]s).<ref name=b12>The Vegetarian Society. ''[http://www.vegsoc.org/info/b12.html Information Sheet: Vitamin B{{ssub|12}}]''. Accessed 26 April 2007.</ref>
[[nori]](Seaweed) contains B<sub>12</sub> very abundantly. <ref>[http://www.mext.go.jp/b_menu/shingi/gijyutu/gijyutu3/toushin/05031802/002/009.pdf ALGAE] from ''[http://www.mext.go.jp/b_menu/shingi/gijyutu/gijyutu3/toushin/05031802.htm STANDARD TABLES OF FOOD COMPOSITION IN JAPAN Fifth Revised and Enlarged Edition 2005]''</ref> However, plant sources of B<sub>12</sub> (or analogues) have not yet been shown to benefit humans. There is a patent for a cultivation method of a mycelium's enriching vitamin B<sub>12</sub> of the
vegetable. <ref>[http://www.wikipatents.com/ca/2431442.html Seed and plant containing vitamin B12 and method of producing the same ]</ref>
=== Omega-3 fatty acids ===
Vegetarian sources of [[omega-3 fatty acid]]s include [[flax|flaxseeds and flaxseed oil]], [[olive oil]], [[walnut]]s, [[canola]] ([[rapeseed]]) oil, [[avocado]], and [[egg (food)|eggs]].
[[Image:English Walnuts.jpg|thumb|left|[[Walnuts]] are a source of [[omega-3 fatty acid]]s]]Vegetarian sources of omega-3 fatty acids are primarily the short chain variety and likely to have lower concentrations of the particular [[essential fatty acid]]s (EFAs), [[eicosapentaenoic acid]] (EPA) and [[docosahexaenoic acid]] (DHA). The body can synthesize small quantities of EPA and DHA from other omega-3 fatty acids, such as [[alpha-linolenic acid]]s, which are present in vegetarian sources of omega-3 fatty acids. The human body can also convert DHA into EPA. DHA supplements derived from DHA-rich [[alga|microalgae]] are available. Whilst the human body can in theory do this conversion, in practice modern diets and lifestyles reduce the effectiveness of the conversion systems. Roughly ten times more of the short chain omega-3s must be consumed to have the same effect as the long chain form from [[fish oil]].<ref>[http://www.seafish.org/pdf.pl?file=seafish/file/consumerHealthInfo.pdf Revised Seafood Briefing DocOct03<!-- Bot generated title -->]</ref>
While there is no [[scientific consensus]] on the role of omega-3 fatty acids, it is generally believed that they may reduce the risk of coronary [[heart disease]], lower [[triglycerides]], stabilize mood and help prevent [[clinical depression|depression]], help reduce symptoms of [[Attention-deficit hyperactivity disorder|ADD]], reduce joint pain and other [[Rheumatism|rheumatoid]] problems and reduce the risk of [[dementia]] in older age.
=== Vitamin D ===
The human body can [[synthesize]] Vitamin D when [[skin]] is exposed to [[ultraviolet radiation]] from the [[sun]]. Vegans who do not eat foods or pills fortified with synthetic vitamin D and with little exposure to the sun's ultraviolet radiation, e.g. who don't expose their extremities for at least 15-30 minutes per day or those living at [[latitude]]s close to the [[geographical pole|pole]]s, are vulnerable to Vitamin D deficiencies.
Vitamin D acts as a [[hormone]], sending a message to the [[intestine]]s to increase the absorption of [[calcium]] and [[phosphorus]], which produces strong [[bone]]s. Vitamin D also works in concert with a number of other [[vitamin]]s, [[mineral]]s, and hormones to promote bone [[mineralization]]. Research also suggests that vitamin D may help maintain a healthy [[immune system]] and help regulate [[cell growth]] and [[cellular differentiation|differentiation]].
=== Iodine ===
According the British Journal of Nutrition there is a "potential danger of [Iodine] deficiency disorders due to strict forms of vegetarian nutrition, especially when fruits and vegetables grown in soils with low [Iodine] levels are ingested."<ref>Thomas Remer, Annette Neubert and Friedrich Manz: “[http://docstore.ingenta.com/cgi-bin/ds_deliver/1/u/d/ISIS/34393885.1/cabi/bjn/1999/00000081/00000001/art00009/3E55FC91FC3793AE1167931465C2FF219D4F166CC9.html?link=http://www.ingentaconnect.com/error/delivery%3Bjsessionid=1270sjtai37ar.henrietta&format=html Increased risk of iodine deficiency with vegetarian nutrition]”. ''British Journal of Nutrition'', 1999, 81:45-49. Accessed 4 January 2007.</ref> Iodine, however, is usually supplied by [[iodized salt]] and other sources in [[First World|first world countries]].
Additionally, it should be noted that any iodine found in animal products is sourced from plant life (see: [[Iodine| Iodine: Sources]]).
=== Riboflavin ===
According to the American Dietetic Association, “Some studies have shown vegans to have lower intakes of [[riboflavin]], compared with nonvegetarians; however, clinical riboflavin deficiency has not been observed.”<ref name="ada"/>
==References==
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<references/>
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==See also==
* [[Nutrition]]
* [[Vegetarian cuisine]]
* [[Vegetarianism]]
* [[Veganism]]
* [[Vegan cuisine]]
* [[The China Study]]
==Further reading==
* [http://www.mayoclinic.com/invoke.cfm?id=HQ01596 Mayo Clinic's synopsis].
* [http://www.vrg.org Vegetarian Resource Group]
* [http://www.vegparadise.com/protein.html Protein Basics Chart]
* [http://www.epic-oxford.org/gen_vegpapers.html Focus on vegetarians] research from EPIC-Oxford.
* [[The China Study]]: The Most Comprehensive Study of Nutrition Ever Conducted and the Startling Implications for Diet, Weight Loss and Long-Term Health (2005) by: T. Colin Campbell ISBN 1-932100-66-0
*[http://www.earthtimes.org/articles/show/13988.html Becoming a 'Veggie' : The Smart Move]
*[http://www.nal.usda.gov/fnic/pubs/bibs/gen/vegetarian07.pdf Vegetarian Nutrition Resource List - USDA, NAL Food and Nutrition Information Center (PDF|72 KB)]
[[Category:Vegetarianism]]
[[it:Diete vegetariane]]
[[ru:Вегетарианское питание]]
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