The following post, plus the Comments that follow it, are copied and pasted from the Dr Rath Foundation's Newsletter.
Arab-American women living in southeast Detroit whose conservative dress limits their exposure to sun should be taking a vitamin D supplement to boost their dangerously low serum levels, according to a study published by Henry Ford Hospital researchers. Researchers found that all 87 women involved in a small study showed vitamin D levels averaging 8.5 ng/mL (nanograms per milliliter) for those who wore western dress to 4 ng/mL for those who wore the hijab, modest dress with a headscarf. A healthy vitamin D level is 30 ng/mL or higher.
Read article at physorg.com
Comment: There is good evidence that not only dress code but also many other factors such as age, sex, contraceptive use, race, geographical location, regular blood donation, medicinal drug use, genetic mutations and biochemical individuality can affect a person's nutrient needs and/or status, sometimes dramatically so.