Getting a little past a decade of smoking here. Over the past few months I've started to feel myself wanting to collapse from exhaustion and difficulty breathing every day. Tried many times to quit, and always finding myself coming back to smoking. So while I'm struggling with quitting, I found out what could improve my health during this time. I found out smoking stripped me of my vitamin D intake. I went to the doctors and they confirmed my vitamin D intake was insufficient, but they only prescribed me 1000 UI a day. They were unwilling to prescribe more due to fear of toxicity, but plenty of new studies have shown that you need to take 40,000 UI a day, every day for months in order to get to the toxicity level. 5,000 UI doesn't even scratch that. Sunlight gives you 10,000-20,000 UI a day. So I went with NatureWise. I was feeling better after a few doses, and now I can say my breathing is normal. I have more energy and I don't feel like collapsing while doing daily activities anymore. When they offered me another bottle for free (any customer who buys one are given this offer), I knew I had to sign up for it. The current bottle is inexpensive, and would last me almost a year, so I'll have to see if this second bottle would expire by that time. I'll probably give it another smoker as a gift. It's not just smokers who need at least 5,000 UI a day, but studies show that many women, particularly, and those who lack Vitamin D need this amount in order to overcome bone density loss. They normally only prescribe 1,000 UI at the doctors, like my mother who has Osteoporosis, and takes medication for her acid reflux (which also depletes her of bone density). It isn't enough, and when she was taken to the ER when she was going through a life threatening emergency involving her jaw, they were almost ready to surgically remove it due to a rare condition where patients have both Osteoporosis AND has to take acid re flux medication. The emergency doctor had to prescribe her a higher vitamin D dosage, something the family doctors are not willing to do. Talk to physicians and do your research if you are lacking Vitamin D