Iodine reaches your hair through your thyroid. The thyroid cannot make its hormones without iodine, and those hormones act directly on hair follicles.
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From Anirva, the maker of Hair Radiance. This article is general information, not medical advice. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
- The thyroid needs iodine to make its hormones. Iodine is an essential part of the two thyroid hormones, T4 and T3 [1].
- Thyroid hormones act directly on hair follicles. In a lab study of human hair follicles, they lengthened the growth phase and raised the growth of hair-forming cells [3].
- Thinning hair is a known sign of an underactive thyroid. The National Institutes of Health lists dry, thinning hair among its common symptoms [2].
- Some food choices leave iodine out. Sea salt and Himalayan salt are not usually iodized, and vegan diets can be low in iodine [1].
- Hair Radiance contains 200 mcg of iodine. With food, the total is under both the US and the European upper limits [1][5][6].
Your body cannot make iodine, and some common food choices today leave it out. This article explains the link between iodine, the thyroid and hair. It also shows how the 200 mcg in Hair Radiance compares with daily needs and the official limits.
Facts at a glance
| Fact | Detail |
|---|---|
| Ingredient and form | Iodine, from organic kelp [6] |
| Amount in Hair Radiance | 200 mcg a day, in 3 capsules [6] |
| Percent of Daily Value | 133% [6] |
| Recommended intake for adults | 150 mcg a day [1] |
| Average intake from food, US | 216 mcg a day, not counting salt added at home [1] |
| Kinds of evidence | Nutrition science; a lab study of human hair follicles; regulator reviews [1][2][3][4][5] |
| Human studies cited here | None of iodine supplements for hair. One lab study used human hair follicles |
| Adult upper limit | 1,100 mcg a day in the US; 600 mcg a day in Europe [1][5] |
| Last reviewed | [DATE] |
What is iodine?
Iodine is a mineral that the body needs in small amounts. It is an essential part of the thyroid hormones thyroxine (T4) and triiodothyronine (T3) [1]. These hormones regulate protein building and metabolism throughout the body [1].
Hair Radiance supplies 200 mcg of iodine from organic kelp [6]. Kelp is a seaweed, and seaweed is a rich food source of iodine [1].
How does iodine support hair?
The thyroid needs iodine to make its hormones
Without enough iodine, the thyroid cannot make enough hormone. When iodine intake falls very low, the result can be an underactive thyroid [1].
Thyroid hormones act directly on hair follicles
A 2008 lab study showed that human hair follicles are direct targets of T4 and T3 [3]. The details are in the research section below.
In people, thinning hair is a sign of an underactive thyroid
The National Institutes of Health lists "dry skin or dry, thinning hair" among the common symptoms of an underactive thyroid [2]. About 5 in 100 Americans aged 12 and older have an underactive thyroid, and most cases are mild [2].
Regulators accept the link with the thyroid and skin
In Europe, labels may say that iodine contributes to the normal production of thyroid hormones and normal thyroid function. They may also say that it contributes to the maintenance of normal skin [4].
Does iodine help hair growth? What the research shows
The research on iodine and hair is still growing. It links iodine to hair through the thyroid. No trial has tested iodine supplements for hair growth.
Thyroid hormones lengthened the growth phase of human hair follicles (2008)
Researchers took hair follicles from the scalp skin of women aged 40 to 69 and kept them growing in the lab. They then added thyroid hormones [3].
T4 raised the growth of hair-forming cells and lengthened the growth phase of the follicles. T3 and T4 both lowered the death of these cells, and both raised pigment production [3]. The authors also note that too little and too much thyroid hormone can each change hair [3].
What each source shows
| Source | Type of evidence | What it shows |
|---|---|---|
| National Institutes of Health, thyroid [2] | Health information | Dry, thinning hair is a common symptom of an underactive thyroid |
| van Beek et al., 2008 [3] | Lab study of human hair follicles | Thyroid hormones lengthened the growth phase |
| European Commission [4] | Permitted label wording | Iodine contributes to normal thyroid function and normal skin |
Who may not get enough iodine?
The general US population gets enough iodine [1]. Some groups are more likely to run low [1]:
- People who do not use iodized salt. Sea salt, kosher salt and Himalayan salt are not usually iodized, and processed foods are almost always made with salt that has no iodine.
- Vegans, and people who eat little or no dairy, seafood or eggs.
- Pregnant women, whose needs are higher.
How much iodine is in Hair Radiance compared with needs and limits?
| Source | Iodine a day | Notes |
|---|---|---|
| Hair Radiance (3 capsules) | 200 mcg | 133% of the Daily Value [6] |
| Recommended intake for adults | 150 mcg | [1] |
| Average intake from food, US | 216 mcg | Not counting salt added at home [1] |
| US upper limit | 1,100 mcg | [1] |
| European upper limit | 600 mcg | [5] |
Hair Radiance provides 200 mcg of iodine, a little more than the daily need. With the average 216 mcg from food, the total is about 416 mcg a day, by our calculation.
This total is under the US upper limit of 1,100 mcg and under the European upper limit of 600 mcg [1][5].
22 ingredients, including 200 mcg of iodine
Hair Radiance is a daily three-capsule supplement that pairs iodine from organic kelp with vitamins, plant extracts and probiotic strains. Every ingredient and amount is listed on the label.
See Hair RadianceWhich foods are high in iodine?
Seafood, dairy foods, eggs and iodized salt are the main sources [1]:
Is iodine safe? Safety and interactions
With iodine, both too little and too much can affect the thyroid. High intakes can cause some of the same problems as low intakes, including an underactive thyroid [1]. The upper limit for adults is 1,100 mcg a day in the United States and 600 mcg a day in Europe [1][5].
People with autoimmune thyroid disease may react to iodine intakes that are safe for the general population [1]. The National Institutes of Health advises people with an underactive thyroid to talk with their health care team about iodine supplements and seaweeds such as kelp [2].
High doses of iodine can add to the effect of medicines for an overactive thyroid [1]. Iodine needs are higher in pregnancy, and pregnant women are advised to ask their doctor how much they need [2].
Iodine is one part of Hair Radiance
Hair Radiance is a daily three-capsule hair growth supplement with 22 ingredients: vitamins, minerals, plant extracts, an amino acid and three probiotic strains. They were chosen to support healthy hair growth, to help promote silky, smooth hair, and to strengthen and maintain healthy hair. Iodine is one of them.
Hair Radiance has not been clinically tested as a finished product. For this reason, we cannot say how its ingredients work together.
Every ingredient and amount is listed on the label [6].
If you are deciding
Here is the case in brief. Your thyroid needs iodine to make its hormones, and your body cannot make iodine [1]. Thyroid hormones act directly on hair follicles, and thinning hair is a known sign of an underactive thyroid [2][3]. Many people get enough iodine from food, but salt that is not iodized and diets without dairy, seafood or eggs can leave it short [1]. Hair Radiance supplies 200 mcg a day, and the total with food stays under both upper limits [1][5][6]. The directions are three capsules a day with food [6].
The short version
The thyroid needs iodine to make its hormones, and those hormones act directly on hair follicles. Thinning hair is a known sign of an underactive thyroid. No trial has tested iodine supplements for hair growth. Hair Radiance provides 200 mcg of iodine a day, which keeps the total with food under both upper limits.
Frequently asked questions
Does iodine help hair growth?
Can low iodine cause hair loss?
Can too much iodine cause hair loss?
How much iodine do adults need?
Adults need 150 mcg a day. The need is 220 mcg in pregnancy and 290 mcg while breastfeeding [1].
How much iodine is too much?
Is kelp a good source of iodine?
Does sea salt have iodine?
Not usually. Sea salt, kosher salt and Himalayan salt are not usually iodized [1].
How much iodine is in Hair Radiance?
Each serving of three capsules has 200 mcg of iodine from organic kelp [6].
References
- National Institutes of Health, Office of Dietary Supplements. Iodine: Fact Sheet for Health Professionals. Updated November 5, 2024. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/ (accessed October 7, 2026).
- National Institute of Diabetes and Digestive and Kidney Diseases. Hypothyroidism (Underactive Thyroid). Last reviewed March 2021. https://www.niddk.nih.gov/health-information/endocrine-diseases/hypothyroidism (accessed October 7, 2026).
- van Beek N, Bodó E, Kromminga A, Gáspár E, Meyer K, Zmijewski MA, Slominski A, Wenzel BE, Paus R. Thyroid hormones directly alter human hair follicle functions: anagen prolongation and stimulation of both hair matrix keratinocyte proliferation and hair pigmentation. J Clin Endocrinol Metab. 2008;93(11):4381-4388. doi:10.1210/jc.2008-0283. PMID: 18728176.
- European Commission. Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods. https://eur-lex.europa.eu/eli/reg/2012/432 (accessed October 5, 2026).
- European Food Safety Authority. Overview on Tolerable Upper Intake Levels as derived by the Scientific Committee on Food (SCF) and the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Version 11, August 2025. https://www.efsa.europa.eu/sites/default/files/2024-05/ul-summary-report.pdf (accessed October 7, 2026).
- Anirva. Hair Radiance Supplement Facts label and product page. https://anirva.com/pages/hair-growth-supplement-with-probiotics (accessed October 7, 2026).
