I'm part of a long-term vitamin D3 study. It's been going on for well over 10 years. Participant D3 blood levels are tested twice a year. The study group of participants with the highest D3 range have 85% fewer fractures than the general population and 60% fewer fractures than participants in the lowest D3 range which is about 32-35.

Vitamin D3 cannot be produced from sun exposure in Boston from November thru March...the last day of any possible sun generated D3 in Boston was November 11. There are calendars for this. In fact a lot of weather reports now include a D3 generation index.

I wouldn't believe anything a general practitioner, oncologist, or D.O. said about D3. I've found they are generally 6-10 years behind in knowledge of D3 research.

I've been studying D3 for over 25 years. Most vitamin D3 experts...real experts...keep their D3 levels over 100. In fact, I have personally spoken to two, Drs. Holick and Hollis, and heard of others that keep theirs in the 120-135 range.

I've seen and heard of D3 miracles related to all kinds of ills/diseases. My family members have experienced quite a few of them.

Oh, and getting enough vitamin D isn't as simple as taking a D3 supplement alone. For optimal results, cofactors such as magnesium, calcium, and vitamin k2 in sufficient amounts are also required. Calcium without k2 is useless.; k2 directs calcium to bone and not tissue. Not enough calcium will cause D3 to leach calcium from your existing bone structure leading to factures and osteoporosis.

My advice is to do your own research via pubmed.

You do you. I'll stick with D3.