FULL CLAIM: Giving water to babies under six months can result in health risks including water intoxication, electrolyte imbalance, reduced nutrient intake, water contamination, and hyponatremia
REVIEW
A Facebook reel posted on 13 June 2024 claimed that giving water to babies under the age of six months can result in health risks, including reduced nutrient intake and infections from contaminated water. It also noted that “too much water can cause low sodium levels, leading to brain swelling, seizures, and even death”.
The reel had received nearly two million views and was shared over 18,000 times at the time of this review’s publication. This claim isn’t new; it previously circulated on Facebook and was reviewed by USA Today in 2023.
As we will explain below, the health risks presented by the reel can indeed result from giving water to infants.
Infants’ bodies aren’t equipped to consume water
The reel made a few claims regarding babies’ bodies and their inability to handle water. First, it claimed “water fills up their tiny stomachs, making them less likely to nurse and get the nutrients they need from breast milk or formula”.
This is correct. Babies’ stomachs do fill up quickly due to their small size. According to health organizations like the Cleveland Clinic and the Alabama Department of Public Health, infants’ stomachs grow from around the size of a pea (at 24 hours old) to the size of an egg or a golf ball (by two weeks to one month old). For context, this translates to a range of roughly five to 50 milliliters of stomach capacity. In comparison, while adult human stomach sizes can vary, they’re generally able to hold one to one and a half liters (1,000-1,500 milliliters) of food.
A review of studies evaluating the introduction of food or fluids other than breast milk or formula to infants further clarified why “filling up” on water can be harmful to babies[1]:
“Water, and glucose in particular, have no or little calorific value and may cause a baby to be full but remain deficient in calorific intake. Supplementation in such instances, as well as interfering with breastfeeding, will in fact contribute to further weight loss in the early postpartum period.”
Contaminated water is dangerous for weak immune systems
The reel also claimed that “babies have weak immune systems, and even a small amount of contaminated water can lead to infections and illnesses”.
This is also correct. Susceptibility to diseases from contaminated water is possible for all humans, not just babies. Germs that contaminate tap water are often spread when fecal matter from infected people makes its way into water sources. These germs are responsible for diseases including cholera, diarrhea, dysentery, hepatitis A, typhoid, and polio.
However, infants’ immune systems are particularly vulnerable to bacteria and viruses. In a 2021 interview with the Cleveland Clinic, pediatric infectious disease specialist Camille Sabella shared that “[a]n infant’s immune system doesn’t mature until they’re about two to three months old.”
Protecting babies from bacteria and viruses is thus critical during this period. Breastfeeding is incidentally one way to build this protection, since breast milk contains antibodies that fight infections. Sterilizing feeding equipment like baby bottles can also help to protect against infections.
Diluted sodium levels in the blood can lead to brain swelling
Sodium is an electrolyte that helps to regulate fluid levels in and around cells. It’s the most abundant electrolyte ion found in the body, and when it’s diluted, it can lead to hyponatremia—a condition that occurs when the concentration of sodium in the blood becomes too low.
The reel claimed that “brain swelling, seizures, and even death” can occur from hyponatremia, and that “excess water can disrupt the balance of electrolytes in a baby’s body, essential for heart and brain function”.
Both of these claims are true. Water intoxication can cause sodium levels to drop, allowing water to enter a baby’s brain cells and cause swelling. This can lead to an excess accumulation of fluid in the brain (cerebral edema), which can cause seizures, coma, and death.
Conclusion
Infants’ delicate physiology and developing systems aren’t equipped to handle consuming water. Breast milk and formula fulfill all of a baby’s nutritional needs prior to the age of six months.
REFERENCES
- 1 – Smith et al. (2016) Early additional food and fluids for healthy breastfed full‐term infants. Cochrane Database of Systematic Reviews.
