Fluoride Affects Brain Health in Children, Fertility, Thyroid Function

By Dr. Linda J. Dobberstein, DC, Board Certified in Clinical Nutrition

August 2, 2022

Fluoride Affects Brain Health in Children, Fertility, Thyroid Function
The widespread, low-level use of fluoride in the American water supply has researchers and many citizens alike concerned about its long-term effects on mental and cognitive health, especially in children.

Cutting-edge research also raises questions about the impact of fluoride on mitochondria and hormonal health. It can potentially affect fertility, thyroid health, and more. Iodine status must be sufficient to help offset these challenges.

Fluoride Sources

Fluoride is a trace mineral naturally found in the soil, foods, and water supply. In general, beverages, legumes, potatoes, grain and cereal products, and root vegetables have higher concentrations of fluoride than other foods. Beverages made with fluoridated tap water often contain the highest amounts of fluoride.

Dietary sources of fluoride include black tea (brewed with tap water), grape juice, sodas, blue crab, shrimp, fruit-flavored water with sweeteners, wine, coffee, tap water, raisins, cooked oatmeal, chocolate almond milk, light beer, black bean soup, cooked carrots, cooked spinach, boiled potatoes, white rice, oysters, and asparagus.

Fluoride has been added to the water supply in much of the United States since 1945 for the prevention of dental cavities. It is added to many dental care products like toothpastes, mouth rinses, and applied as dental treatments. Despite its acceptance in the U.S., other countries however have banned or restricted water fluoridation.

Children at Higher Risk

Fluoride impacts various age groups and sexes differently concerning neurological development. Boys appear to be more susceptible to these neurodevelopmental challenges than girls.

Infants and children retain 80-90 percent of ingested fluoride, whereas adults retain 50-60 percent. Most research focuses on early life exposure as higher fluoride retention and exposure during pregnancy and infancy affects brain development.

Research in older age groups and brain health is less robust, but its impact is felt as an endocrine disrupting compound.

High Fluoride Intake and Low Iodine Status

A new July 2022 Canadian study presented concerns and findings about preschool age children who lived in areas with higher fluoride exposure. Study results showed that children who had lower iodine intake with high fluoride intake had lower IQ scores.

Boys were more adversely affected in their neurological development. Boys who had adequate iodine intake even with high fluoride exposure however experienced less neurotoxicity.

In a different 2021 study, children ages 7-12 in China underwent several tests of fluoride levels and thyroid measurements. Thyroid enlargement was noted in boys with higher fluoride levels and low iodine status. Girls were not significantly impacted in this setting. It was found that adequate iodine intake helped protect against fluoride induced thyroid gland changes.

Additional Effects of the Fluoride/Iodine Imbalance

Animal studies with low iodine stores and high fluoride exposure also provided evidence of neurological cellular changes. Microscopic examination of brain tissue in rats showed increased free radicals and oxidative stress, apoptosis (cell death), and significant structural changes in nerves.

Fluoride Competes Against Iodine

Iodine and fluoride have similar chemical structures and can bind to the same receptor sites in the thyroid gland, gonads, and elsewhere in your body. Fluoride however is bigger and heavier. It competes against iodine and will occupy receptor sites meant for iodine when it is lacking in your body.

Endocrine Disrupting Compound Effects: Thyroid and Other Hormones

Fluoride exposure is associated with higher levels of thyroid stimulating hormone (TSH) and lower levels of T4 and T3 thyroid hormone levels which reflects sluggish thyroid hormone activity. Fluoride blocks enzymes related with iodine function and activation and can also block iodine uptake in the thyroid gland. High fluoride intake or low iodine intake are both independently related with greater likelihood of low thyroid function.

Other findings suggest that fluoride may impact other endocrine systems. Probable adverse effects may occur with parathyroid hormone levels, insulin/blood sugar and pancreas function, and cortisol production by the adrenal glands.

Fertility and Sex Hormones

Fluoride’s endocrine disruption effects may affect sex hormones and fertility. It was found that men living in a fluoride polluted area had lower testosterone levels and significantly higher levels of LH (Luteinizing Hormone) compared to the control group.

Scientists believe this reflects a disruption in the communication loop between the testes and testosterone production and the brain. They concluded that fluoride’s endocrine disruptive effects on male reproduction may be more severe than the effects on women.

In adolescent female rats, a single exposure of sodium fluoride also evoked an increase in estrogen and LH hormones in estrogen receptor genes.

Luteinizing hormone is released by the brain to signal the ovaries or testes for hormone production. An LH surge happens prior to ovulation in women. Men have LH surges that stimulate the testes to make testosterone. Higher LH levels associated with lower hormone production reflect fertility stress.

Fluoride, Other Brain Effects, and Mitochondria Dysfunction

Researchers also documented behavioral and mitochondrial changes in the study of fluoride’s effect on fertility. Rats exposed to fluoride during pregnancy or early infancy experienced slower spatial learning, difficulty with short and long-term memory, depression, and anxiety tendencies. Males were also more prone to hyperactive behaviors.

Fluoride was also found to cross into the hippocampus where it caused neurological irritation and dysfunction. This part of the brain is involved with memory, learning, and emotions.

Neurotransmitter changes have been found. Increased levels of serotonin, glutamate, and histamine with lower levels of acetylcholine and dopamine were seen in the brains of rats. This affected mood stability, learning, memory, focus, and motivation, and hyperactivity in animals.

Fluoride exposure induced mitochondrial dysfunction and mitochondria DNA changes. Swollen, damaged mitochondria with high levels of reactive oxygen species (ROS), loss of cell membrane integrity, changes in the myelin sheath (fatty insulation layer around nerves), and cell death/apoptosis were identified.

Fluoride appeared to suppress mitochondrial biogenesis or the birth of new mitochondria.
Investigations show that fluoride affects signaling pathways that regulate mitochondrial proteins like SIRTI which impair mitochondrial biogenesis.

Mitochondria health and vitality is required for neurotransmitter and cognitive function, brain energy dynamics, hormone regulation, mood and much more.

The Fluoride Battle

Disagreements run deep between researchers, professional organizations, health advocates, and governments on fluoride safety and risk. In recent years, the National Toxicology Program has published multiple extensive literature reviews on the effects of fluoride. They are “moderately confident” in the association between fluoride exposure and negative neurodevelopmental impacts on IQ, cognitive abilities, and mood/mental development in children.

They have received considerable criticism against their findings and reports on changes within cell, fish, and animal studies from the American Dental Association and other organizations citing bias, improper conclusions, and need for more research. The battle of fluoride usage and risk will undoubtedly continue for many years.

Choices and Support

Fluoride exposure is ubiquitous in the food and water supply in America. Think about your exposure levels. Consider your choices and exposures with fluoride and your total body burden. You may want to consider water filters to remove fluoride and to re-evaluate your dental care products and treatment choices. More information may be found at

Iodine and Other Nutritional Support

Iodine is critical to bind onto iodine receptor sites before fluoride jumps in. Many individuals on low salt diets or who only use sea salt may lack adequate iodine. Iodine status is critical for women and men in family planning stages but affects all ages. It is important to keep your iodine levels optimal.

Iosol Iodine is an excellent water-soluble iodine supplement that may be used by children and adults. More in-depth information on iodine may be found in the article What’s Your Iodine Status?

Other nutrients have also been found helpful in protecting the brain and tissues against the oxidative stress induced by fluoride exposure. These include resveratrol and turmeric/curcumin.

Neurological development, lifelong brain health, thyroid, estrogen, testosterone and other hormones, and mitochondria are sensitive to many things in the environment including fluoride exposure. Your body’s tolerance to chronic low level fluoride exposure is affected by your iodine and antioxidant status as well as food and beverage choices.

The health and physiology of individuals today is directly impacted by choices made in the past. Blatant changes are readily seen in people today with obesity, infertility, and other hormone effects. Be proactive today to help yourself and future generations.

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