(Part 23 of 25 in series, M. Eades' Blog)
Most of the US and Europe are too far north to get enough sun exposure to generate the production of adequate vitamin D during a large part of the year. And, second, most parents are so fearful of sunburn that they slather their kids with sunscreen if and when they let these children play outside during the part of the year they can make adequate vitamin D. Since a sunscreen with an SPF of only 8 reduces the synthesis of vitamin D by 95 percent, think of how little vitamin D children with sunscreens of SPF 30 or 45 are making. Zero.
~ Michael Eades from, http://www.proteinpower.com/drmike/supplements/sunshine-superman/
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