Yes, low vitamin B12 levels can trigger excessive shedding and thinning by starving hair follicles of oxygen and nutrients needed for growth.
Vitamin B12 is one of the few vitamins responsible for the production of red blood cells that oxygenate scalp follicles—lack of it leads to the weakening of follicles, hence, to telogen effluvium (diffuse shedding). In the case of long-term hair loss, research reveals that as many as 35% of women may be suffering from a lack of B12, which is usually accompanied by symptoms of fatigue and anemia.
Since B12 is derived primarily from animal foods, the groups of people such as vegans, elderly, and people with digestive problems should be most concerned about their B12 supply.
Get a blood test—deficiency is indicated when the level is below 200 pg/mL. Most people relieve the problem by means of supplementation (1-2 mg daily) or injections within 3-6 months. They should also take the condition seriously and consider adding eggs, meat, dairy, or fortified cereals to their diet. It is advisable to check iron and folate levels as well, since deficiencies in these nutrients often co-exist.
It is very encouraging to note that B12 fixes are very reliable and quick—are smart with supplements, do a test early and your hair will be back before you know it.
Myth: Only taking supplements will magically restore your hair overnight. Truth: The recovery of the hair follicle is a slow process and takes from 3 to 6 months, thus one has to exercise patience.
Myth: Only vegans need B12. No, your absorption will decline as you get older or in case you suffer from pernicious anemia.
Vegans/vegetarians who do not consume fortified foods.
People over 50 with reduced stomach acid.
Those with celiac, Crohn's, or metformin use.