Limitations of the study of sunscreen which make it inconclusive −
1. They only measured blood levels during summer. They would have declined in winter, and were not actually that terrific in either group even at the end of summer, though not at the levels of frank deficiency. Differences would have widened over winter and with ongoing use/non-use of sunscreen over time, as vitamin D is stored in body fat.
2. The study was small and short term and thus major effects could show up as N.S. E.g the 50% greater increase in the placebo group of over 70s was not found “statistically significant”. The confidence intervals were very wide so the result should be seen as inconclusive and tending towards sunscreen reducing D levels rather than definitively showing no major effect over time.
Limitations of the study of sunscreen which make it inconclusive −
1. They only measured blood levels during summer. They would have declined in winter, and were not actually that terrific in either group even at the end of summer, though not at the levels of frank deficiency. Differences would have widened over winter and with ongoing use/non-use of sunscreen over time, as vitamin D is stored in body fat.
2. The study was small and short term and thus major effects could show up as N.S. E.g the 50% greater increase in the placebo group of over 70s was not found “statistically significant”. The confidence intervals were very wide so the result should be seen as inconclusive and tending towards sunscreen reducing D levels rather than definitively showing no major effect over time.