Misleading: Evidence shows that the blood-brain barrier (BBB) forms during gestation and is functional by the third trimester of pregnancy. The claim that the BBB isn’t fully formed in infants younger than six months of age leads to an inaccurate understanding of BBB integrity in infants.
FULL CLAIM: “The blood-brain barrier is not fully formed until 6 months of age […] Fluoride can cross the blood brain barrier in infants […] Fluoride does a lot of damage to bones and teeth and potentially the brain […] Babies need to be drinking breast milk, otherwise they need to be drinking distilled water or reverse osmosis water with minerals added to it because baby's brains are not able to protect themselves from the chemicals in the water”
REVIEW
Fluoride is a naturally occurring mineral that helps prevent tooth decay. It does so by strengthening tooth enamel and making teeth more resistant to acid attacks from plaque bacteria and sugars in the mouth, which can lead to dental caries (cavities).
Fluoridation is the process of adding fluoride to public water supplies in controlled amounts with the purpose of improving dental health. It’s supported by numerous health organizations, including the World Health Organization (WHO) and the American Academy of Pediatric Dentistry (AAPD). According to the AAPD, “[f]luoride has proven to be an effective therapy in reducing the prevalence of dental caries in infants, children, adolescents, and persons with special needs.”
An Instagram reel posted on 5 March 2024 claimed that fluoridated water is unsafe for babies to drink because their brains’ protective barriers aren’t fully formed until six months of age. It claimed that babies should only drink breast milk or water stripped of all minerals and chemicals. It also claimed that fluoride damages teeth and bones, and that it has the potential to damage the brain.
The reel was posted by Robert W. B. Love, who describes himself as a neuroscientist that specializes “in helping people prevent Alzheimer’s disease with science”. However, his LinkedIn profile doesn’t list credentials in neuroscience. Instead, it lists a masters in psychology from the University of Texas at Austin and a PhD in cognitive psychology that was completed online. Love, who has 1.2 million followers on Instagram, also sells a lion’s mane supplement that he claims will improve brain health, despite a lack of clinical evidence for this claim.
Science Feedback previously reviewed claims on the purported harms of fluoride. We found no evidence indicating that fluoridated water causes cognitive or other health problems or that fluoride is associated with neurological damage.
Fluoride levels in drinking water don’t damage teeth or bones
The reel’s claim that fluoride damages the bones and teeth isn’t entirely accurate. As mentioned earlier, fluoride actually helps to protect teeth by strengthening enamel and reducing the risk of cavities.
Many communities in the U.S. choose to fluoridate their water supplies because of these dental health benefits. The recommended fluoride level in community water sources in the U.S. is 0.7 milligrams of fluoride per liter of water (mg/L). According to the U.S. Centers for Disease Control and Prevention (CDC), this level of fluoride is optimal for reducing the risk of dental caries while also limiting the risk of dental fluorosis. The CDC adds:
“Because of its contribution to the large decline in cavities in the United States since the 1960s, CDC named community water fluoridation one of 10 great public health achievements of the 20th century.”
The reel also seems to conflate dental fluorosis with skeletal fluorosis, two conditions of very different severity. Dental fluorosis is a generally harmless condition that can cause changes to the appearance of tooth enamel. Most cases of dental fluorosis in the U.S. are mild and don’t impact dental function.
Skeletal fluorosis, on the other hand, is a bone disease that can occur as a result of excessive fluoride consumption. It causes joint pain and stiffness due to an accumulation of fluoride in the bones and major joints.
As we explained in a previous claim review, excessive fluoride consumption prior to age eight—by which point permanent teeth are generally formed—can lead to dental fluorosis.
However, it’s unlikely that fluoridated drinking water could be responsible for the development of skeletal fluorosis. As a report from the National Academy of Medicine (previously known as the Institute of Medicine at the time of the report’s publication) evaluating skeletal fluorosis risk explained:
“The development of skeletal fluorosis and its severity is directly related to the level and duration of exposure. Most epidemiological research has indicated that an intake [of fluoride] of at least 10mg. per day for 10 or more years is needed to produce clinical signs of the milder forms (arthritis like symptoms, and some radiographically evident osteosclerosis of pelvis and vertebrae) of the disease.”
The CDC also commented in response to this report:
“This daily intake level necessary to produce skeletal fluorosis or even its early signs far exceeds that level of fluoride received by people on fluoridated community water systems even when factoring in other daily fluoride exposures typical in the U.S.”
In short, any substance consumed in large quantities has the potential to be harmful. As we pointed out in a previous claim review about fluoride, the dose makes the poison. So while fluoride can lead to harm when consumed in large doses, the levels of fluoride in U.S. drinking water aren’t high enough to be associated with health problems.
It’s safe for infants to drink formula mixed with fluoridated water
The post claimed that “babies need to drink breast milk, distilled water, or reverse osmosis water with added minerals”.
The claim about breast milk is accurate per recommended guidelines from the WHO. The WHO recommends that infants be breastfed for at least the first six months of life to facilitate intake of important nutrients and antibodies.
However, not all infants are or can be breastfed. In the case of formula-feeding, powdered infant formula must be mixed with water prior to consumption.
According to the CDC, it’s safe for powdered infant formula to be mixed with fluoridated water. Because powdered infant formula may increase the risk of mild dental fluorosis, the CDC also recommends using low-fluoride bottled water (labeled as “de-ionized, purified, demineralized, or distilled”) to minimize this risk.
This may be where the post’s suggestion to use “distilled water” or “reverse osmosis water with added minerals” stems from.
The blood-brain barrier forms and matures during gestation
The claim that the blood-brain barrier (BBB) isn’t fully formed until six months of age misleading. For context, the BBB is a semipermeable membrane that both protects the brain from harmful substances and aids in important processes such as transporting nutrients and hormones[1].
According to NeoReviews, a journal published by the American Academy of Pediatrics (AAP):
“The blood-brain barrier is present and functional early in fetal life. The tightness of the barrier gradually increases throughout gestation and in the newborn period.”
Additional reviews also concur that the BBB forms as early as 12 weeks of gestation[2], and that the BBB is formed and functional by the third trimester of pregnancy.
Further, the permeability of the BBB isn’t necessarily related to its formation or maturation. The potential for fluoride to cross the BBB may have to do with the ability that some molecules have to cross the BBB in people of any age, not just infants[3].
According to a review published by Saunders et al.:
“At some point a belief, which has persisted for nearly 100 years, arose that in embryos, fetuses and even in the newborn and older, the blood-brain barrier is absent, leaky or immature […] The developing brain in all respects is by definition yet to reach a mature adult state and therefore can rightly be described as immature. But this does not tell us whether its brain barriers are “leaky.” The real question is their functional status, which seems to us to be more a matter of the relation between barrier functions (which are much more than the presence or absence of passive permeability) that are present at any particular age and stage of brain development.”[4]
To this point, the integrity of the BBB can be weakened by factors that impact its permeability at different points throughout a person’s lifetime, including inflammation, infections, toxins, and certain chronic health conditions, including Alzheimer’s disease, high blood pressure, type 2 diabetes, and multiple sclerosis.
Conclusion
Fluoride helps strengthen tooth enamel and reduces the risk of cavities. These dental health benefits render it a useful public health resource when added to community water sources. Because excess fluoride can lead to potential health problems, U.S. authorities have suggested limits for the level of fluoride in drinking water. These limits help to ensure that people receive the benefits of fluoride while reducing the risks of dental and skeletal fluorosis. It’s safe for people of all ages, including infants, to consume fluoridated water.
REFERENCES
- 1 – Partridge WM. (1981) Transport of nutrients and hormones through the blood-brain barrier. Diabetologia.
- 2 – Mallard et al. (2018) The myth of the immature barrier systems in the developing brain: role in perinatal brain injury. The Journal of Physiology.
- 3 – Spittle B. (1994) Psychopharmacology of fluoride: a review. International Clinical Psychopharmacology.
- 4 – Saunders et al. (2014) The rights and wrongs of blood-brain barrier permeability studies: a walk through 100 years of history. Frontiers in Neuroscience.
