futile

Guallar et al. (2013) analizan investigaciones sobre el uso de suplementos de vitaminas y minerales para: 1) prevenir o evitar el avance de enfermedades crónicas; o para, 2) mejorar la salud de personas sanas sin deficiencias nutricionales.

Most supplements do not prevent chronic disease or death, their use is not justified, and they should be avoided. This message is especially true for the general population with no clear evidence of micronutrient deficiencies.
With respect to multivitamins, the studies published in this issue and previous trials indicate no substantial health benefit. This evidence, combined with biological considerations, suggests that any effect, either beneficial or harmful, is probably small. As we learned from voluminous trial data on vitamin E, however, clinical trials are not well-suited to identify very small effects, and future trials of multivitamins for chronic disease prevention in well-nourished populations are likely to be futile.
Beta-carotene, vitamin E, and possibly high doses of vitamin A supplements are harmful. Other antioxidants, folic acid and B vitamins, and multivitamin and mineral supplements are ineffective for preventing mortality or morbidity due to major chronic diseases.

Torito! La conclusión sigue siendo la misma: cuando no existe deficiencia, su uso es inútil y en altas dósis algunas son peligrosas.

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Guallar, Eliseo; Saverio Stranges; Cynthia Mulrow; Lawrence J. Appel and Edgar R. Miller_III. 2013. Enough is enough: Stop wasting money on vitamin and mineral supplements. Annals of Internal Medicine, 159(12): 850-851 doi:10.7326/0003-4819-159-12-201312170-00011.

vía:
la ciencia y sus demonios: Basta ya de malgastar el dinero en vitaminas y suplementos minerales // Link