I provide my sources via in-text citations and in the references at the end. This information does not replace medical consultation or blood tests. Consultation with a doctor or nurse practitioner or pharmacist should be sought for diagnosing and treating nutrient deficiencies. If you have no health insurance or your insurance does not cover diagnostic testing (which includes testing for nutrient deficiencies), ask at your local clinic or pharmacy about on-demand testing or independent lab testing, but please plan supplements with the guidance of a qualified physician or pharmacist.
IRON
In pre-menopausal women, low serum (blood) ferritin is one of the more common causes of hair thinning or pattern hair loss. ©Science-y Hair Blog 2015
When you get a typical blood test - the iron test is often for hemoglobin. That is the form of iron in your blood that can carry oxygen to your tissues. If it is low, you are anemic. If you are anemic - your hair may be thinning. But recently, researchers have questioned how low is truly a"low" level for ferritin in relation to syndromes like thinning hair and female pattern hair loss and restless legs syndrome. Ferritin is a form of iron that is stored in your liver - like a "bank" of iron from which your body makes withdrawals when it needs iron. We use iron for a lot of processes in our bodies. If you think of your body like a machine made from lots of different materials - including metals - then naturally there's going to be some iron here and there and in a lot of places, playing a lot of roles. Carrying oxygen is only one of iron's roles in your body.
If your ferritin is low, you don't have the back-up supply or iron you need. You can shuttle oxygen around, but other functions suffer. Like hair growth.
How much ferritin is enough? The level that will be flagged as low on a blood test is around 10 ug/l (that's micrograms per liter). But studies of hair loss or thinning indicate that ferritin levels need to be above 40-50 ug/l (Rasheed et al.) or up to 70 ug/l (Rushton, Song et al.) to prevent iron-related hair loss. For women, ferritin levels up to 300 ug/l are still within the normal range, so 70 ug/l doesn't appear to be an excessive target.
What does that mean for you? If you see a doctor for hair loss, ask to have your ferritin tested as well. If it is lower than 40-70 ug/l, discuss a reasonable strategy for getting your ferritin level up above 40-70 ug/l. Closer to 70 seems to be indicated at the cut-off point above which hair loss can't be called iron-related (people without hair loss have levels that high or higher, but more women with hair loss have low ferritin levels).©Science-y Hair Blog 2015
Iron supplements are the usual treatment, but they can be dangerous, even deadly, so a blood test is necessary and so is follow-up re-testing to see how the supplement is working. Iron supplements can also be difficult to take, with common side effects being nausea, stomach pain, and constipation. To avoid nausea, take the supplement with food. To avoid constipation, magnesium citrate supplements or stool softeners are common remedies. Taking iron with vitamin C can increase your absorption of iron up to 100%. 250 mg of vitamin C provides the greatest boost in iron absorption (Cook and Reddy).©Science-y Hair Blog 2015
Coffee, high-calcium foods (dairy products) and foods high in phytate (beans, whole grains) all interfere with iron absorption - avoid eating/drinking those at the same time as you take an iron supplement if possible.©Science-y Hair Blog 2015
VITAMIN D
Low vitamin D levels have also recently been associated with thinning hair and female pattern hair loss. Low vitamin D is becoming more common as people spend less time outdoors, and wear sunscreen and protective clothing. A study by Rasheed et al found a vitamin D level below 30 nmol/liter (nanomoles per liter) which is the same as 12 ng/l (nanograms per liter) was associated with thinning hair or female pattern hair loss. This level is also considered a serious deficiency in vitamin D.
Vitamin D levels need to be above 67 nmol/l (27 ng/ml) to no longer be associated with thinning hair. The National Institute of Health (NIH) indicates that a level of 50 nmol/l or greater (20 ng/ml) is adequate for most healthy adults, so that seems a reasonable target for women with hair thinning or hair loss.©Science-y Hair Blog 2015
Vitamin D comes from the sun, getting enough sunlight on your face and arms or legs or back a few times per week can be all it takes to get enough - it takes only a few minutes. In many quite Northern (or Southern in the Southern Hemisphere) latitudes, you really don't get vitamin D from the sun in winter, even if you are a fan of bikini ice fishing (I sincerely hope that's not a real thing). If you can correlate your latitude in line with any of these cities, you can calculate your UV exposure to get enough vitamin D: http://zardoz.nilu.no/~olaeng/fastrt/VitD-ez_quartMED.html
There are many food sources of vitamin D also, see this page for sources - this is from the Skin Cancer Foundation, who don't want us over-exposed to the sun: http://www.skincancer.org/healthy-lifestyle/vitamin-d/make-vitamin-d-not-uv-a-priority
Vitamin D can also can and should be checked by a blood test, especially if you plan to take supplements because vitamin D supplements can also be toxic in too-large doses over time. For people taking supplements, talk with a pharmacist about a safe amount to supplement (stop in when they're not too busy - they're very knowledgeable). It is possible to over-supplement with natural vitamin D sources like cod liver oil, so it's best to plan supplementation carefully if you use natural sources also.©Science-y Hair Blog 2015
People over the age of 50 cannot synthesize vitamin D from the sun as well as before age 50 and may need supplements to stay in the "normal" zone - which is important in maintaining muscle and bone health and preventing falls.
Bottom line:
To prevent iron-related hair thinning, have blood ferritin levels tested and maintain a level around 70 ug/l, assuming you are healthy. This is higher than the level that a laboratory will label as a deficiency which is 10 ug/l or below. The clinical "low" it too low for hair-maintaining purposes.©Science-y Hair Blog 2015
If you donate blood regularly- get your ferritin checked! You lose a lot of iron with every blood donation. Women also lose large amounts of iron during childbirth.
To prevent vitamin D deficiency-related hair thinning, keep vitamin D levels well in the normal range for healthy adults, 20-50 ng/ml (~50-70 nmol/l), though the study cited indicates that hair loss is less likely toward the higher end of that range.
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Decreased Serum Ferritin and Alopecia in Women. Journal of Investigative Dermatology 2003
D Hugh Rushton
Effect of ascorbic acid intake on nonheme-iron absorption from a complete diet. American Society for Clinical Nutrition 2001, 93-98
Cook JD, Reddy MB
Iron Plays a Certain Role in Patterned Hair Loss. Journal of Korean Medical Science 2013, 934-938
Song Youn Park, Se Young Na,Jun Hwan Kim, Soyun Cho, Jong Hee Lee
Serum ferritin and vitamin d in female hair loss: do they play a role? Skin Pharmacology and Physiology 2013, 101-107
Rasheed H, Hahgoub D, Hegazy R., El-Komy M, Abdel Hay R, Hamid MA, Hamdy E.