"The epidemic of obesity has added to the epidemic of vitamin D deficiency. Because vitamin D is fat-soluble, excess body fat will pull vitamin D out of circulation, thus contributing to lower levels."
Source:
https://www.drmcdougall.com/misc/2015nl ... tamind.htm"Mary [McDougall] is not an unusual example of well-sunned people failing this commonly prescribed test. Similar results were found during a study of active young people living in Hawaii with an average sun exposure of 29 hours a week. Even with all that vitamin D-promoting solar radiation, 51 percent of the group failed to meet sufficiency levels of 30 ng/mL.6 The highest reported level was 62 ng/mL and several people had values below 20 ng/mL. Another study of 495 women with an average age of 74 years, living in Hawaii, a geographical area with high environmental UV irradiance, found 44 percent of subjects had vitamin D values of less than 30 ng/mL, but none were below 10 ng/mL; and there was little evidence of seasonal variation of vitamin D levels.7"
"Based on recent reviews, adequate, I believe, is 20 ng/mL or greater (see below)..."
Source:
https://www.drmcdougall.com/misc/2011nl/mar/vitd.htm