Iodine: Why Functional Doctors Say Most of Us Are Low, Thyroid and Breast Health, and Who Needs Caution

Americans' iodine levels fell by more than half in about 20 years, and functional doctors like Dr. David Brownstein believe most people are low. Here's why iodine matters for the thyroid, breasts, and more, what the research shows, why some functional experts urge caution with Hashimoto's, and what to know before you start.

MK Wellness InsightsFounded by Danielle Cordova, Cypress, TX

Iodine is an essential mineral: your body can't make it, and your thyroid can't make hormones without it. Functional doctors like Dr. David Brownstein believe most people today are low, and that iodine matters far beyond the thyroid, in the breasts, ovaries, and prostate too.

It's also one of the few nutrients where respected functional experts disagree, especially about Hashimoto's. Here's what iodine does, what each side says, what the research shows, and what to know before you start.

What It Is

Iodine is a trace mineral found in seafood, seaweed, eggs, dairy, and iodized salt. Your thyroid uses it to build its two main hormones, T4 and T3, which set the pace of your metabolism, energy, and body temperature. T4 carries four iodine atoms, and T3 carries three.

When iodine runs low, the thyroid can enlarge (a goiter), and low iodine in pregnancy can affect a baby's developing brain (Journal of Clinical Endocrinology & Metabolism, 1998).

How It Works in the Body

• Thyroid hormones. Every thyroid hormone molecule is built from iodine, so the thyroid depends on a steady supply.
• Beyond the thyroid. Dr. Brownstein points out that iodine also concentrates in the breasts, ovaries, uterus, and prostate. In his view, low iodine is behind many problems in those tissues, starting with cysts and nodules.
• The bromide problem. Bromide, fluoride, and chlorine belong to the same chemical family as iodine. Functional doctors believe they compete with iodine in the body, and Dr. Brownstein says bromide can even take iodine's place. Regulators have since moved on bromide in food: in 2024, the FDA banned brominated vegetable oil after FDA and NIH studies found it could harm the thyroid at levels close to what people actually consume (FDA), and California's Food Safety Act bans it, along with potassium bromate used in some breads, starting in 2027 (Food Safety Magazine).

What Functional Doctors Say

• Dr. David Brownstein, a board-certified family physician, medical director of the Center for Holistic Medicine in Michigan, and author of Iodine: Why You Need It, Why You Can't Live Without It, is iodine's best-known advocate. He reports that more than 97% of the over 8,000 patients his office has tested were low. He pairs iodine with unrefined salt and other supporting nutrients, and, unlike some practitioners, he believes iodine helps people with Hashimoto's rather than harming them (Dr. Jill Carnahan's podcast, 2024).
• Dr. Guy Abraham, a former UCLA professor of obstetrics, gynecology, and endocrinology, launched the Iodine Project in 1997. He argued that the body needs far more iodine than official guidelines suggest.
• Dr. Izabella Wentz, a clinical pharmacist and New York Times bestselling author known as the Thyroid Pharmacist, urges caution with Hashimoto's. She explains that Hashimoto's works differently from simple iodine deficiency: high amounts of iodine can inflame the thyroid in people who are prone to it, especially without enough selenium to protect it (Wentz).
• Dr. Alan Christianson, a naturopathic physician and author of The Thyroid Reset Diet, goes further: he teaches that for many people with Hashimoto's or an underactive thyroid, lowering excess iodine helps the thyroid recover.

Where they agree: iodine is essential, supporting nutrients matter, and testing with an experienced practitioner beats guesswork.

Why People Choose It

• Thyroid support, especially with signs like fatigue, feeling cold, weight gain, dry skin, and brain fog
• Breast health, including tender, lumpy (fibrocystic) breasts and cyclic breast pain
• To help clear bromide and other look-alike chemicals, in Dr. Brownstein's approach
• Low intake, for people who skip seafood and iodized salt, or use sea salt instead
• Pregnancy and breastfeeding, when iodine needs rise

What the Research Shows

• Iodine levels have fallen. A CDC analysis of national survey data found that Americans' median iodine levels dropped by more than half between 1971–1974 and 1988–1994. Low levels became 4.5 times more common, and 14.9% of women of childbearing age had low levels (Journal of Clinical Endocrinology & Metabolism, 1998).
• Breast health. Across three studies of women with fibrocystic breasts, molecular iodine worked best of the forms tested; in the double-blind study, 65% improved, compared with 33% who felt better on placebo (Canadian Journal of Surgery, 1993). In a randomized, placebo-controlled trial of 111 women with cyclic breast pain, iodine reduced pain, more than half of the women on the highest amount had a meaningful drop in pain, and side effects didn't rise with the amount (Breast Journal, 2004).
• Alongside breast cancer treatment. In a randomized pilot study of 60 women in Mexico, adding molecular iodine to chemotherapy eased side effects, and every woman on chemotherapy plus iodine responded to treatment. Five years later, 82% of those who took iodine before and after surgery were disease-free, compared with 46% of those who started after surgery. The researchers have registered a larger trial (Nutrients, 2019).
• Too much can backfire. In a five-year study of more than 3,000 people in China, those living where iodine intake was more than adequate or excessive developed more underactive thyroid (mostly mild) and more autoimmune thyroiditis than those with mildly low intake (New England Journal of Medicine, 2006). That's the caution Dr. Wentz and Dr. Christianson emphasize.
• Selenium protects the thyroid. In an overview of reviews covering 75 randomized trials, selenium lowered thyroid antibodies at 3 and 6 months in people with autoimmune thyroiditis (Nutrients, 2023).

What to Know Before You Start

We don't share doses or protocols. An iodine-literate practitioner can guide you.

How to Find a Practitioner

Look for an "iodine-literate" practitioner, as Dr. Brownstein puts it: a functional or integrative doctor who tests before and during, and who knows thyroid disease well. The Natural Health Network directory can help you find holistic practitioners near you.

Common Questions

Isn't iodized salt enough? Functional doctors disagree. Dr. Brownstein believes most people need more than salt provides, while Dr. Christianson believes many people with thyroid problems get too much. Testing shows where you stand.

What about seaweed? Seaweed is one of the richest natural sources of iodine, and the amount varies widely by type. Kelp can be especially high.

Does iodine help with detox? Dr. Brownstein believes iodine, taken with unrefined salt, helps the body release bromide.

Do you sell iodine at MK? No. We share the research so you can decide with your practitioner.

How This Fits at MK Wellness

• Real food first: seafood and pasture-raised eggs are natural sources of iodine, alongside the protein, vegetables, and fruit we recommend.
• Hormone support: see Thyroid Labs for Women, the Hormone Health guide, and the free Perimenopause Toolkit.
• Lower your toxic load: a deep sweat in the infrared sauna is part of how many of our clients support detox.

Go Deeper

• Iodine: Why You Need It, Why You Can't Live Without It, by Dr. David Brownstein
• Iodine, the Misunderstood Nutrient, Dr. Jill Carnahan's interview with Dr. Brownstein
• The Effect of Iodine on Hashimoto's, by Dr. Izabella Wentz
• The Thyroid Reset Diet, by Dr. Alan Christianson
• Holistic Therapies: The Basics, and every holistic and alternative guide

MK Wellness services are non-medical and not intended to diagnose, treat, cure, or prevent any condition. This article is general education, not medical advice, and deliberately includes no doses or protocols. Talk with your practitioner before taking iodine, especially if you have a thyroid condition, are pregnant or breastfeeding, or take medication.

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