Although rare, deficiency in biotin can cause hair thinning and hair loss. You could be at risk of a deficiency if you develop unexplained hair loss, it's been revealed. Why Vitamin B12 is Essential for Hair Growth (and to Delay Good food sources include liver, whole grains, eggs, and vegetables. Vitamin deficiency hair loss . Getting too little vitamin is one cause of hair loss, according to a 2010 study published in the journal of oncology practice.while researchers don't say why exactly vitamin d deficiency is associated with thinning hair, vitamin d supplementation can help correct the problem. Vitamin d plays an important role in stimulating your hair follicles. Vitamin d supplements could help if a vitamin d deficiency is the cause of your hair loss. Vitamin d is the most common culprit of hair loss when it comes to vitamin deficiency. A vitamin d deficiency may cause numerous problems, including hair loss. Folic acid deficiency can lead to hair loss because...