Bladderwrack
Brown algaes contain the highest amount of iodine in the seaweed family. Bladderwrack, a kind of kelp, is especially rich in iodine. According to the University of Maryland Medical Center, an iodine deficiency may result in hypothyroidism, or underactive thyroid. One symptom of hypothyroidism is dull, scaly or slow-growing hair. UMMC notes that lack of the proper amount of iodine is rare in the developed countries, so check with your doctor to make sure you don't overdo it on iodine. If she agrees that it may help in your case, however, prepare kelp with meals about once a week, or take 600 mg supplements one to three times a day, UMMC advises. Kelp is also rich in vitamin B12. A B12 deficiency which can also lead to sluggish hair growth and other health problems. Herbal author Phyllis Balch notes that bladderwrack is a good source of B12 for vegans, because most other food sources of the vitamin come from animals. She notes that kelps in general have some of the highest available concentrations of trace minerals. It is also high in macronutrients, like protein and fatty acids, which add shine to hair.
Read more:
http://www.livestrong.com/article/305520-which-seaweeds-promote-hair-growth/#ixzz1MoIoiKYJ