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Springy -> RE: mamice vegetarijanke (31.8.2009 22:52:06)
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IZVIRNO SPOROČILO: Felicita
@ Springy: pa poglejmo kak strokoven članek:
Four GLV were found to have approximately 40% bioavailable iron, while the others were in the range of 6-30%.
(Journal of the Science of Food and Agriculture, naslov članka: In vitro bioavailability of calcium and iron from selected green leafy vegetables)
Although plant foods tend to be rich sources of trace elements such as copper, manganese, and iron, animal products provide most of the zinc in US diets (1), and meat, poultry, and fish provide some iron in the highly bioavailable heme form. The bioavailability of dietary iron and zinc can be reduced considerably by the phytic acid and possibly other constituents of some plant foods.
(American Journal of Clinical Nutrition, cel članek na voljo: http://www.ajcn.org/cgi/content/full/78/3/633S)
pa lej, lahk se greva do ju3 iskanje argumentov za in proti. kot pravm, I give up.
Nihče ne osporava boljše absorbcije hem železa, s temi svojimi "citati" si samo dokazala nekaj, kar že vemo in temu ne nasprotujemo, to je jasno in tega nihče ne osporava. Dejstvo pa je, da absorbcija železa na daljši rok ne vpliva na kazalnike železa v krvi. In to je dokazano izdatno v znanstveni literaturi:
Nonheme-iron absorption, fecal ferritin excretion, and blood indexes of iron status in women consuming controlled lactoovovegetarian diets for 8 wk, American Journal of Clinical Nutrition, Vol. 69
Janet R. Hunt, Zamzam K. Roughead
"Background: The characteristics of vegetarian diets suggest that these diets would have lower dietary iron bioavailability than nonvegetarian diets, but there is no evidence of iron deficiency in vegetarians....Most studies of vegetarians in Western societies have not found poorer iron status in vegetarians than in omnivores on the basis of measurements of hemoglobin, hematocrit, serum iron, iron binding capacity, or transferrin saturation..."
"Conclusions: .... an insensitivity of blood iron indexes, including serum ferritin, to substantial differences in dietary iron absorption for 8 wk."
Primerjava med dvemi tipi prehrane žensk, s kontroliranimi, kalorijsko usklajenimi jedilniki, eden vsebuje meso, drugi je vegetarijanski. Raziskava ugotavlja, da kjub precejšni razliki v absorbiciji železa v obeh dietah po 8 tednih ta razlika nima nobenega vpliva na kazalce količine železa v krvi, kar je v POPOLNEM NASPROTJU s trditvijo, da vegetarijancem primanjkuje železa oz. da je pri vegetarijanski prehrani težko dobiti dovolj železa.
Tudi v uvodu raziskovalci ugotavljajo, da večina sorodnih primerjav v zahodnih državah med vegetarijanci in mesojedimi prav tako ni ugotovila slabšega stanja železa pri vegetarijancih.
Tu lahko pripomnim, da je bila v raziskavi izbrana nemesna dieta z izjemno velikim deležem inhibitorjev absorbcije (3x vecja količina fitatov, 2,5x večja količina vlaknin) ter brez povečane količine vitamina C, ki absorbcijo izboljšuje (torej kar se da pesimistična izbira za vegetarijanski jedilnik). Kljub temu razlik v statusu železa ni bilo.
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Iron status of vegetarians, American Journal of Clinical Nutrition, Vol 59
WJ. Craig
"An appropriately planned well-balanced vegetarian diet is compatible with an adequate iron status. Although the iron stores of vegetarians may be reduced, the incidence of iron-deficiency anemia in vegetarians is not significantly different from that in omnivores."
Tudi ta raziskava ugotavlja, da ni bistvenih razlik v slabokrvnosti med osebami, ki se prehranjujejo z vegetarijansko ali mesno prehrano. Ugotavlja, da so lahko zaloge serumskega železa brez mesa v krvi nekoliko manjše, vendar še vedno v mejah normale. Naj tu poudarim, da nižja vrednost serumskega železa ni z nobeno meni znano raziskavo povezana s kakršnim koli zdravstvenim tveganjem, obstaja pa precej raziskav, ki povezujejo povečano vrednost tega železa z povečanim tveganjem nekaterih oblik raka in srčnih obolenj.
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Physical fitness and vegetarian diets: is there a relation?, American Journal of Clinical Nutrition, Vol. 70
David C. Nieman
"The available evidence supports neither a beneficial nor a detrimental effect of a vegetarian diet on physical performance capacity, especially when carbohydrate intake is controlled for. Concerns have been raised that an emphasis on plant foods to enhance carbohydrate intake and optimize body glycogen stores may lead to increases in dietary fiber and phytic acid intake to concentrations that reduce the bioavailability of several nutrients, including zinc, iron, and some other trace minerals. There is no convincing evidence, however, that vegetarian athletes suffer impaired nutrient status from the interactive effect of their heavy exertion and plant-food based dietary practices to the extent that performance, health, or both are impaired. Although there has been some concern about protein intake for vegetarian athletes, data indicate that all essential and nonessential amino acids can be supplied by plant food sources alone as long as a variety of foods is consumed and the energy intake is adequate. There has been some concern that vegetarian female athletes are at increased risk for oligoamenorrhea, but evidence suggests that low energy intake, not dietary quality, is the major cause. In conclusion, a vegetarian diet per se is not associated with improved aerobic endurance performance. Although some concerns have been raised about the nutrient status of vegetarian athletes, a varied and well-planned vegetarian diet is compatible with successful athletic endeavor."
Tu ni kaj dodati, raziskava lepo pokaže, da tudi pri športnikih, ki ne jedo mesa ni pomanjkanja železa in drugih mineralov.
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Dietary intake and nutritional status of young vegans and omnivores in Sweden, American Journal of Clinical Nutrition, Vol. 70
Christel L. Larsson, Gunnar K. Johansson
"Results: ...There was no significant difference in the prevalence of low iron status among vegans (20%) and omnivores (23%). "
Raziskava je ugotavljala prehranske navade prostoživečih veganov (ki ne jedno ne mesa, mleka, jajc) ter vsejedov. Skupini sta bili usklajeni po starosti, spolu in telesni višini. Ugotavlja vnos cele vrste mikro in makrohranil, delež "junk food" v prehrani, energijsko vrednost itd. Glede statusa železa podobno kot ostale študije tudi ta ugotavlja, da ni znatnih razlik v pomanjkanju serumskega železa med vegani in tistimi, ki jedo meso.
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Adaptation of iron absorption in men consuming diets with high or low iron bioavailability, American Journal of Clinical Nutrition, Vol. 71
Janet R. Hunt and Zamzam K. Roughead
"Short-term measurements of iron absorption are substantially influenced by dietary bioavailability of iron, yet bioavailability negligibly affects serum ferritin in longer, controlled trials."
Dve skupini moških sta v kontroliranih pogojih uživali dve različni dieti v trajanju 12 tednov. Prva dieta je bila bogata z rdečim mesom in hem železom, druga je bila brez rdečega mesa z zelo malo hem železa. Po dvanajstih tednih se je absorbcija nehem železa zelo povečala pri skupini z malo hem zeleza in zelo zmanjšala v skupini z veliko hem zeleza. Skupna absorbcija železa je bila veliko večja v skupini z več hem železa, vendar tudi pri tej raziskavi ni bilo nobenih razlik v indikatorjih železa v krvi (feritin, hemoglobin) med obema skupinama.
Raziskava ugotavlja, da lahko kratkoročni testi, ki merijo absorbcijo železa ob enem samem obroku, pretirano ocenijo pomembnost absorbcije železa iz hrane. Nadalje ugotavlja, da je nivo absorbcije oz. tip železa (hem, nehem) čez daljše obdobje manj pomemben, saj regulacijski mehanizmi telesa uravnavajo zaloge železa na optimalnem nivoju.
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How important is dietary iron bioavailability?, American Journal of Clinical Nutrition, Vol. 73
Janet R. Hunt
Članek, kjer avtorica razpravlja o razlikah med absorbcijami železa, izmerjenimi v enem samem obroku in meritvah absorbcije preko daljših obdobij. Razlika v absorbciji je precejšnja, regulacijski sistem v telesu pa deluje v smeri ohranjanja serumskega železa, ki ostaja dokaj konstantno ne glede na tip diete.
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Dietary intake and iron status of Australian vegetarian women, American Journal of Clinical Nutrition, Vol. 70
Madeleine J. Ball, Melinda A. Bartlett
"Despite the possible overall health benefits of a vegetarian diet, there is concern that some vegetarians and infrequent meat eaters, particularly females, may have inadequate iron status because of low or no heme-iron intakes.
Results: ....similar numbers of vegetarians (18%) and omnivores (13%) had serum ferritin concentrations <12 µg/L, which is a value often used as an indicator of low iron stores. Hemoglobin concentrations were not significantly different."
Raziskava primerja prostoziveče vsejede ženske z vegetarijankami. Najprej ugotavlja, da ima velika večina žensk iz obeh skupin vnos železa manjši kot je priporočena dnevna doza. Podobno kot druge raziskave ugotavlja, da je količina serumskega feritina višja pri skupini, ki je meso, vendar je tudi v vegetarijanski skupini feritin v mejah normale. Tudi ta raziskava ugotovi, da ni bistvene razlike med skupinama v količini oseb z premajhno količino feritina, prav tako ni razlik v količini hemoglobina med obema skupinama.
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Bioavailability of iron, zinc, and other trace minerals from vegetarian diets, American Journal of Clinical Nutrition, Vol. 78
Janet R Hunt
"The iron and zinc from vegetarian diets are generally less bioavailable than from nonvegetarian diets because of reduced meat intake as well as the tendency to consume more phytic acid and other plant-based inhibitors of iron and zinc absorption. However, in Western countries with varied and abundant food supplies, it is not clear that this reduced bioavailability has any functional consequences. Although vegetarians tend to have lower iron stores than omnivores, they appear to have no greater incidence of iron deficiency anemia."
Še en članek, ki enako kot vse gornje raziskave ugotavlja, da tip železa v hrani bistveno ne vpliva na pomanjkanje železa v telesu ter da pojavnost slabokrvnosti zaradi pomanjkanja železa ni nič bolj pogosta pri vegetarijancih kot pri mesojedih.
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The iron and zinc status of long-term vegetarian women, American Journal of Clinical Nutrition, Vol 34
BM Anderson, RS Gibson, JH Sabry
"The iron and zinc status of long-term Seventh-Day Adventist vegetarian women appeared adequate despite their low intake of readily absorbed iron and zinc from flesh foods and their high intake of total dietary fiber and phytate."
Še ena raziskava, ki tako kot vse ostale ugotavlja, da imajo vegetarijanske ženske zadostne količine železa in cinka, kjub temu da ne uživajo.
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Torej, vse gornje raziskave so enotne in spodbijajo trditve o pomanjkanju oz. problemu železa pri vegetarijanski prehrani. Da tu razblinimo kakšne arogantne dvome o strokovnosti, oz. insinuacije da so "citirane samo določene raziskave", citiram ugotovitve prej omenjenih dietetičnih organizacij glede železa, ki je v popolnem soglasju z mojim stališčem in ugotovitvami gornjih raziskav:
"Incidence of iron deficiency anaemia among vegetarians and vegans are similar to non-vegetarians therefore vegans and vegetarians are not at greater risk from this condition. Vegetarians and vegans have lower iron stores compared to non-vegetarians however their serum ferritin levels are usually within the normal healthy range"
In seveda, če meniš, da se 75.000 strokovnjakov o prehrani moti ... saj veš, piši jim, pa jih poduči o njihovi zmoti. Pa plis, še meni kopijo maila. [image]http://www.ringaraja.net/forum/smileys/smiley1.gif[/image]
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