DO NOT BUY IT

I did, and will be asking for a refund

Here are just a few of the huge number of problems

(not bothering to provide links to the correct material on the VitaminDWiki)
Author considers 20 ng/ml be to good
Time in the sun 5-20 minutes twice a week on face, arms, and legs
No comment about more needed by elderly, dark skinned
Food: does not distinguish farmed from wild salmon
Considers D2 to be acceptable Mushrooms are great
No apparent mention of co-factors
Pregnancy – seems to need more than 400 IU
Vitamin D supplements (at 400 IU) did not relieve arthritis pain
Vitamin D supplements (at 400 IU) did not prevent breast cancer
Vitamin D supplements (at 400 IU) did not prevent colon cancer
Vitamin D supplements (at 400 IU) DID prevent skin cancer – but study was too small
Vitamin D supplements (at 3000 IU average) did not stop COPD
Systematic reviews found no evidence that Cognition helped by vitamin D – again far too low
Vitamin D supplements (at 800 IU) did not stop depression
Vitamin D supplements (at 800 IU) did not stop falls by the elderly
Vitamin D supplements (at 400 IU) did not reduce risk of heart problems
Vitamin D2 (did not state how much) given annually did not help the heart
Vitamin D supplements (at 400 IU) did not reduce risk of bone fractures
Bottom line: middle ground take 800 to 1,000 IU per day

Note about the author:

He is not listed as even a co-author in a single vitamin D article in PubMed

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