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发表于 2008-1-21 01:18 PM
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高级错误
个别实验可能有错, 那么《中国居民膳食指南(2007)》的结果是如何总结出来的呢?奉劝大众常吃肉食,等于否定饮食多样化,忽视素食合理性,这是经过什么样的研究获得的?。有人天生就是素食者,按照这样的膳食指南岂不是必需接受治疗?!熊猫800万年以前是肉食动物,可是现在吃竹子,试图改成肉食在理论上也是可能的。成都熊猫动物中心试图给熊猫配制其它饲料,但终因严重腹泻而失败。
食物相生相克是中医食疗的内容,可能有一些不正确的地方,但也不能就此否定相生相克这个现象本身。现代医学中也发现大量的相生相克现象(附录一)。
...。
用高级错误取代低级错误,同样有损健康。
饮食中的维生素C不会有危险,但额外补充维生素C的危险性是存在的。首先是过量维生素C会引起中毒。其次,即使常量维生素C也不一定对身体一定有好处。附录二来自本人在丁香园的帖子“运动训练的中医代谢组学研究”(http://www.dxy.cn/bbs/post/view? ... amp;tpg=1&age=0)
附录一 [讨论] 相生相克
http://www.tiyuol.com/thread-4607-1-1.html
附录二 大量服用抗氧化剂导致死亡率增加
2007年2月28日出版的国际权威医学杂志《美国医学会杂志》(JAMA)发表了一项由多国研究人员共同完成的研究(Bjelakovic et al 2007)(见附件)。其中,丹麦哥本哈根大学医院的一个小组是该研究主要单位。
这项发表于国际权威医学杂志的大型研究显示,服用维生素E死亡率增加4%,服用茁胡萝卜素死亡率增加7%,服用维生素A死亡率增加16%,没有证据表明维生素C能延年益寿。
本人评论:如果因为维生素不足导致功能下降,可以适当补充维生素恢复内稳态。如果于维生素适当的内稳态,再进一步补充大量的维生素,只能造成机体远离内稳态,自然有Bjelakovic 等人(2007)指出的结果。
对于运动员,Atalay等人(2006)也指出抗氧化剂的补充必须慎重。根据内稳态理论本人认为,除非氧化应激引起了严重的病理情况,运动员的抗氧化能力必须依靠运动训练本身来解决。
参考文献
Atalay M, Lappalainen J, Sen CK. 2006. Dietary antioxidants for the athlete. Curr Sports Med Rep. 2006 Jun;5(4):182-6. Physical exercise induces oxidative stress and tissue damage. Although a basal level of reactive oxygen species (ROS) is required to drive redox signaling and numerous physiologic processes, excess ROS during exercise may have adverse implications on health and performance. Antioxidant nutrients may be helpful in that regard. Caution should be exercised against excess antioxidant supplements, however. This article presents a digest for sports practitioners. The following three recommendations are made: 1) it is important to determine the individual antioxidant need of each athlete performing a specific sport; 2) multinutrient preparations, as opposed to megadoses of any single form of nutrient, seem to be a more prudent path to choose; and 3) for outcomes of antioxidant supplementation, performance should not be the only criteria. Overall well being of the athlete, faster recovery, and minimization of injury time could all be affected by antioxidant therapy.
Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. 2007. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis. JAMA. 2007 Feb 28;297Musical Note:842-57.CONTEXT: Antioxidant supplements are used for prevention of several diseases. OBJECTIVE: To assess the effect of antioxidant supplements on mortality in randomized primary and secondary prevention trials. DATA SOURCES AND TRIAL SELECTION: We searched electronic databases and bibliographies published by October 2005. All randomized trials involving adults comparing beta carotene, vitamin A, vitamin C (ascorbic acid), vitamin E, and selenium either singly or combined vs placebo or vs no intervention were included in our analysis. Randomization, blinding, and follow-up were considered markers of bias in the included trials. The effect of antioxidant supplements on all-cause mortality was analyzed with random-effects meta-analyses and reported as relative risk (RR) with 95% confidence intervals (CIs). Meta-regression was used to assess the effect of covariates across the trials. DATA EXTRACTION: We included 68 randomized trials with 232 606 participants (385 publications). DATA SYNTHESIS: When all low- and high-bias risk trials of antioxidant supplements were pooled together there was no significant effect on mortality (RR, 1.02; 95% CI, 0.98-1.06). Multivariate meta-regression analyses showed that low-bias risk trials (RR, 1.16; 95% CI, 1.05-1.29) and selenium (RR, 0.998; 95% CI, 0.997-0.9995) were significantly associated with mortality. In 47 low-bias trials with 180 938 participants, the antioxidant supplements significantly increased mortality (RR, 1.05; 95% CI, 1.02-1.08). In low-bias risk trials, after exclusion of selenium trials, beta carotene (RR, 1.07; 95% CI, 1.02-1.11), vitamin A (RR, 1.16; 95% CI, 1.10-1.24), and vitamin E (RR, 1.04; 95% CI, 1.01-1.07), singly or combined, significantly increased mortality. Vitamin C and selenium had no significant effect on mortality. CONCLUSIONS: Treatment with beta carotene, vitamin A, and vitamin E may increase mortality. The potential roles of vitamin C and selenium on mortality need further study.
对网址 “维生素致死论”遭国内外专家质疑“(http://www.heb.chinanews.com.cn/news/kjqy/2007-03-12/17526.shtml)质疑的评论:
*“’试验人群‘是病人并不科学“
“试验人群”是否病人并不是问题的关键,关键是这些病人并不是因为维生素缺乏引起的。换句话说,这些病人虽然有癌症或心脏病等病但在维生素方面处于内稳态。
在维生素是否处于内稳态这个方面外国人与中国人没有什么不同,因此,Bjelakovic 等人(2007)的研究结果当然适合中国人。
[ 本帖最后由 刘承宜 于 2008-1-21 01:42 PM 编辑 ] |
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