any vitamind D product is chemical... i ask you this... how can you mass produce sunlight? that is vitamid D-only source... so why are docs prescribing it> or anything else.. rally look into any vitamin products. some of them when analysed had none of the above. and you wondered why it doesnt work> interestingly the docs dont want them to work and why their so fake.. pharma knows best... yest ye forget?? (sarcasm)