How many are needed? The answer is at your fingertips ....
The modern take on vitamin d is summarised in the recent New Scientist article referenced below (unfortunately behind a paywall), which recommends more sunlight and much lower supplements.
https://www.scientificamerican.com/article/vitamin-d-hope-and-hype-cosmic-voids-and-preventing-depression/
10-15 minutes a day gives only 1,000 IU of vitamin D in the summer to youths lying down with 25% of white skin exposed,
250 IUs: Summer exposure for elderly with white skins lying down for 10-15 minutes
250 IUs: Summer exposure for those with dark skins, lying down for 10-15 minutes
<250 IUs: Winter exposure for white skin youths who are lying down with 25% of skin exposed
----------------------------------------------------
Howver. normal-weight people actually need at least 4,000 IU, not 1,000 IU
Obese people need at least 8,000 IUs
https://hlahore.substack.com
Hundreds of references are at https://vitamindwiki.com/tiki-index.php?page_id=5047
The modern take on vitamin d is summarised in the recent New Scientist article referenced below (unfortunately behind a paywall), which recommends more sunlight and much lower supplements.
https://www.scientificamerican.com/article/vitamin-d-hope-and-hype-cosmic-voids-and-preventing-depression/
10-15 minutes a day gives only 1,000 IU of vitamin D in the summer to youths lying down with 25% of white skin exposed,
250 IUs: Summer exposure for elderly with white skins lying down for 10-15 minutes
250 IUs: Summer exposure for those with dark skins, lying down for 10-15 minutes
<250 IUs: Winter exposure for white skin youths who are lying down with 25% of skin exposed
----------------------------------------------------
Howver. normal-weight people actually need at least 4,000 IU, not 1,000 IU
Obese people need at least 8,000 IUs
https://hlahore.substack.com
Hundreds of references are at https://vitamindwiki.com/tiki-index.php?page_id=5047