Letter to the Editor Sigrun Chrubasik, University of Freiburg 21 March 2012 With great interest we have read the recent contribution by Willershaus et al. . In contrast to the authors' conclusion, the exploratory study with per protocol analysis shows that consumption of mucronutrients over 3 months did not have any significant effect on oral and general health in dental students prior to exams. Mean SBI at baseline was somewhat lower in the control group and mean LDL somewhat higher in the verum group. Analyses should have considered this as possible confounding. The question remains how many healthy volunteers under stress need to consume the micronutrients that one will achieve a clinical meaningful improvement in oral and general health? What did the authors expect; an increase in total antioxidative capacity? A decrease in oropathogenic bacteria? In light of the fact that micronutrients may increase mortality in the long run rather than being useful for primary and secondary prevention , the conclusion of the study by Willershaus and colleagues  is not justified. An exploratory study that does not consider possible confounders in the analyses cannot provide a definitive conclusion on effectiveness. References 1) Willershausen B, Ross A, Försch M, Willershausen I, Mohaupt P, Callaway A. The influence of micronutrients on oral and general health. Eur J Med Res 2011;16(11):514-8. 2) Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis. JAMA 2007;297(8):842-57. Competing interests I declare I have no competing interests.