The article presented info on the use of vitamin D in hair loss, a recent area of research that has started coming up in the past few years. Hair replacement surgery and the use of Rogaine or Propecia has been the standard of care for some time now, but these treatments are not fully effective, and come with side effects or hefty price tags. Vitamin D may prove to be an important ally in reversing baldness, but the research is still very preliminary.
What has been shown is this - the vitamin D receptor has a role to play in determining whether a hair follicle is active or dormant, and that interfering with the activity of the receptor, either positively or negatively, can either stimulate or decrease hair growth. Additionally, vitamin D can promote follicle growth in the lab in conjunction with traditional treatment, suggesting that it may have an important role to play as an adjunct to treatment.
However, though this is all very intriguing, there isn't a lot of clinical information to go on yet. We don't know if people with healthy vitamin D levels have less baldness and we don't know if taking vitamin D supplements helps prevent or reverse baldness. Having read the article, I did a literature search, and found that, actually, very little research has been done into vitamin D and hair loss, and that most focuses on less common forms of baldness.
The most common form of chronic baldness is androgenic baldness, also called male pattern baldness, which is believed to be caused by an excess of DHT, a metabolite of testosterone. Propecia and some natural treatments are aimed at reducing the conversion of testosterone to DHT, thus preventing male pattern baldness. However, other causes of baldness include dietary deficiencies, hypothyroidism, chemotherapy, and severe stress - these causes are reversible, and can be resolved using treatments meant to target these specific causes. The point is that hair loss can be attributed to a wide variety of vastly disparate causes, and so a unified treatment is going to be difficult to devise. While vitamin D has shown some interesting results in the lab, its only clinical evidence relates to less common types of baldness, and I've not found any information about that all important holy grail of baldness, male pattern baldness. Future research may show that vitamin D may be effective in this condition, but at the moment we're best to rely on better understood, more common treatments.
Of course, vitamin D can be effective in a variety of conditions, and optimal vitamin D levels help to prevent a variety of conditions, and so health-conscious Americans should continue to work to achieve and maintain optimal vitamin D levels, but for now, consuming large amounts of vitamin D supplements with the hope of regrowing hair is ill-advised.