According to Gram Research analysis, children who develop cavities are nearly twice as likely to be underweight, with low family income being the strongest risk factor. A 2026 longitudinal study of 122 Brazilian preschoolers found that cavity incidence increased the risk of low weight by 86%, while reduced family income increased it by 294%. This suggests that poor nutrition—a shared cause of both cavities and inadequate growth—is the underlying connection between these two common childhood health problems.
A new study from Brazil followed 122 preschoolers for one year to understand how tooth cavities and body weight are connected. Researchers found that children who developed cavities were more likely to be underweight, and families with lower incomes faced even greater challenges. The study suggests that poor nutrition—which can lead to both cavities and low weight—is a shared problem affecting young children’s health. These findings highlight how dental health and overall nutrition are deeply connected in early childhood development.
Key Statistics
A 2026 longitudinal study of 122 Brazilian preschoolers found that children who developed cavities were 1.86 times more likely to be underweight compared to cavity-free children over a one-year follow-up period.
According to research reviewed by Gram, low family income was the strongest predictor of underweight status in preschoolers, increasing the risk by 3.94 times in a 2026 Brazilian cohort study of 122 children.
A 2026 study of 122 preschoolers found that maternal education’s apparent influence on child weight (RR=4.67) largely disappeared when family income was considered, suggesting financial resources matter more than parental knowledge.
Research from a 2026 Brazilian longitudinal study of 122 children showed that cavity incidence and low family income were the two most significant risk factors for underweight status in preschoolers.
The Quick Take
- What they studied: Whether children who develop tooth cavities are more likely to be underweight, and what family factors influence this connection
- Who participated: 122 Brazilian children aged 3 to 4 years old, followed for one year between 2017 and 2018
- Key finding: Children who developed cavities were nearly twice as likely to be underweight. Low family income was the strongest predictor of underweight status, making children nearly 4 times more likely to weigh too little.
- What it means for you: If your child has cavities or is underweight, they may share the same underlying cause: poor nutrition or limited access to healthy food. Addressing diet quality could help both problems. However, this study shows association, not that one causes the other.
The Research Details
This was a longitudinal study, meaning researchers followed the same children over time rather than comparing different groups at one moment. Scientists measured 122 preschoolers when they started the study and again one year later, tracking which children developed cavities and how their weight changed. They also collected information about family income and mother’s education level to understand what other factors might influence children’s health. This approach is stronger than a simple snapshot because it shows what actually happens to real children over time.
Following children over time helps researchers understand cause and effect better than just looking at one point in time. By measuring the same children twice, scientists could see which factors appeared first and which problems developed together. This design is particularly valuable for understanding childhood health because children change rapidly.
The study was conducted in a real-world setting in Brazil with careful measurements at two time points. The sample size of 122 children is moderate—large enough to find real patterns but small enough that results should be confirmed by larger studies. The researchers controlled for multiple factors like family income and maternal education, which strengthens confidence in the findings. However, the study was limited to one region of Brazil, so results may not apply everywhere.
What the Results Show
The main finding was a clear connection between developing cavities and being underweight in preschoolers. Children who developed cavities during the year were 1.86 times more likely to be underweight compared to children without cavities. This means that if 10 children without cavities were underweight, roughly 19 children with cavities would be underweight. Family income emerged as the strongest factor: children from families earning less money were 3.94 times more likely to be underweight. Interestingly, while mother’s education initially seemed important, this effect largely disappeared when researchers accounted for family income, suggesting that money—not just knowledge—is the key barrier.
The study revealed that low family income and cavity development were the two most significant risk factors for underweight status in preschoolers. The connection between these factors suggests they share a common cause: inadequate nutrition. Children from lower-income families likely have less access to nutritious foods, which can lead to both poor dental health (cavities) and insufficient weight gain. The fact that maternal education’s importance diminished when income was considered suggests that parents may understand good nutrition but lack the resources to provide it.
This research aligns with existing knowledge that both cavities and malnutrition are linked to poverty and inadequate diet. Previous studies have shown these conditions often occur together in children from disadvantaged backgrounds. However, this Brazilian study adds new evidence by following the same children over time, confirming that cavity development and low weight are genuinely connected rather than just coincidentally occurring together. The findings support the growing recognition that oral health and overall nutrition are inseparable in childhood development.
The study included only 122 children from one region of Brazil, so results may not apply to other countries or populations. The one-year follow-up period is relatively short—longer studies might reveal different patterns. The researchers couldn’t prove that cavities cause low weight or vice versa, only that they’re associated. Other unmeasured factors—like overall food quality, specific nutrients, or health conditions—might explain the connection. Additionally, the study relied on measurements at just two time points, which limits understanding of how these conditions develop.
The Bottom Line
Parents and caregivers should prioritize both dental care and nutrition, recognizing these are connected health issues. Regular dental checkups and fluoride toothpaste can prevent cavities. Ensuring children eat nutrient-rich foods—even on a limited budget—supports both dental and overall health. Healthcare providers should screen children with cavities for nutritional problems and vice versa. Communities should work to improve food access for low-income families, as this appears to be a root cause of both problems. Confidence in these recommendations is moderate, based on this single study.
Parents of preschoolers, especially those with limited income, should pay attention to these findings. Pediatricians and dentists should recognize the connection between cavities and underweight status. Public health officials should consider these findings when designing nutrition and dental programs for young children. Families struggling with food access should seek resources like WIC (Women, Infants, and Children) programs. Children who are underweight or have cavities need evaluation for nutritional adequacy.
Changes in diet quality may improve dental health within weeks to months as new teeth develop without cavities. Weight gain from improved nutrition typically appears within 2-3 months in young children. However, establishing healthy eating habits takes longer—expect 6-12 months to see sustained changes in both dental and nutritional status.
Frequently Asked Questions
Is there a connection between cavities and being underweight in young children?
Yes. A 2026 study of 122 preschoolers found children with cavities were 1.86 times more likely to be underweight. Both conditions likely stem from poor nutrition and limited access to healthy foods, particularly in low-income families.
What causes both cavities and low weight in preschoolers?
Low family income and inadequate nutrition are the primary shared causes. Children from lower-income families have less access to nutritious foods, which increases risk for both dental problems and insufficient weight gain.
Can improving my child’s diet help prevent cavities and support healthy weight?
Absolutely. Nutrient-rich foods support both dental health and growth. Focus on calcium-rich foods (milk, cheese), protein, and limit sugary snacks. Dental improvements may appear within weeks; weight changes typically show within 2-3 months.
Does a parent’s education level affect whether their child gets cavities?
Education matters less than family income. A 2026 study found that while maternal education initially seemed important, its effect disappeared when accounting for income, suggesting financial resources are the key factor.
Should my pediatrician check for cavities if my child is underweight?
Yes. Research shows these conditions are connected, so children with one problem should be screened for the other. Both may indicate inadequate nutrition requiring intervention.
Want to Apply This Research?
- Track your child’s dental visits and any cavities found, alongside monthly weight measurements from pediatric checkups. Record the dates of cavity development and weight changes to identify patterns over time.
- Use the app to set reminders for twice-daily tooth brushing with fluoride toothpaste and plan weekly meals emphasizing calcium-rich foods (milk, cheese, yogurt) and protein. Log meals to ensure adequate nutrition, particularly for families with budget constraints.
- Monitor cavity incidence at dental visits (every 6 months) and weight at pediatric checkups (typically every 3-6 months for preschoolers). Track correlations between dietary improvements and both dental and weight outcomes over 6-12 months.
This research shows an association between cavities and low weight in preschoolers but does not prove one causes the other. These findings are from a single study of 122 Brazilian children and may not apply to all populations. Always consult with your pediatrician or dentist regarding your child’s specific health concerns. This article is for educational purposes and should not replace professional medical or dental advice. If your child is underweight or has cavities, seek evaluation from qualified healthcare providers.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.