Gram Research analysis of a 2025 study of 155 children with autism found that 57% had vitamin D deficiency and 32% were overweight or obese, yet weight didn’t predict vitamin levels. This means children with autism need blood tests for vitamins and diet reviews, not just weight checks, because nutrition problems can hide even in children who look healthy.
A new study from Saudi Arabia looked at the health and nutrition of 155 children and teenagers with autism spectrum disorder. Researchers found that many of these young people had problems with their weight, height, and vitamin levels. About 57% didn’t have enough vitamin D in their blood, and many weren’t eating enough food overall. The study shows that kids with autism need special attention to their nutrition, not just checking their weight. Doctors should look at what these children are actually eating and test their vitamin levels to catch problems early.
Key Statistics
A 2025 cross-sectional study of 155 children with autism in Saudi Arabia found that 56.9% had vitamin D deficiency and another 32.0% had vitamin D insufficiency, meaning 89% of participants didn’t have adequate vitamin D levels.
In the same 2025 study of 155 children with autism, 31.6% were overweight and 20.6% had obesity, while 14.2% were stunted or severely stunted, showing a wide range of weight problems in the group.
A 2025 study of 71 children with autism found they were eating only 68.7% of the calories they needed each day and getting just 12.1% of their recommended vitamin D intake.
Researchers found that in 155 children with autism, body weight did not significantly predict vitamin D, iron, or folate levels, meaning a child could appear healthy by weight but still have hidden vitamin deficiencies.
The Quick Take
- What they studied: Whether children and teenagers with autism have problems with their weight, growth, and vitamin levels, and how these problems connect to each other.
- Who participated: 155 children and teenagers (ages 4 to 18) with autism from a specialist center in Riyadh, Saudi Arabia. About 90% were boys. All had been officially diagnosed with autism by doctors.
- Key finding: More than half of the children had vitamin D deficiency, about one-third were overweight or obese, and many weren’t eating enough food. Surprisingly, their weight didn’t predict their vitamin levels, meaning a child could look healthy but still have hidden vitamin problems.
- What it means for you: If you have a child with autism, checking their weight alone isn’t enough. Doctors should also test their vitamin levels and ask about what they’re eating, because nutrition problems might not be obvious just by looking at them.
The Research Details
This was a cross-sectional study, which means researchers took a snapshot of children’s health at one point in time rather than following them over months or years. Between January and May 2025, researchers at an autism center in Saudi Arabia measured 155 children with autism. They checked their height and weight using standard methods, measured their body fat using a special machine that sends harmless electrical signals through the body, and took blood samples to test for vitamin D, iron, and folate levels. They also asked families about what their children were eating for about three days to understand their diet.
The researchers compared the children’s measurements to international standards to see if they were the right height and weight for their age. They looked at whether children who were heavier also had higher vitamin problems, and whether eating less food meant lower vitamin levels. This approach helps doctors understand the full picture of a child’s nutrition, not just whether they look thin or heavy.
Many children with autism have eating challenges because of sensory sensitivities or behavioral issues, which can affect their nutrition. This study is important because it’s one of the first to carefully measure both weight and vitamin levels in children with autism in the Middle East. Understanding these patterns helps doctors know what to look for and what to test for when caring for children with autism.
This study has some strengths and some limitations. The researchers used proper medical equipment and blood tests, which is good. However, only 155 children participated, and most were boys, so the results might not apply equally to girls with autism. Only 46% of families provided detailed food records, so the diet information is less complete. The study was done in one center in Saudi Arabia, so results might be different in other countries with different foods and healthcare systems. The researchers did not follow children over time, so we can’t know if these problems got better or worse.
What the Results Show
The study found that children with autism in this group had multiple nutrition problems happening at the same time. About 14% were too short for their age, 10% were underweight, 32% were overweight, and 21% had obesity. This means the group had a wide range of weight problems, not just one type.
Vitamin D was the biggest concern. When researchers tested blood samples, 57% of children had vitamin D deficiency (very low levels), and another 32% had vitamin D insufficiency (low but not severely low). This means 89% of the children didn’t have enough vitamin D. About 28% had low iron levels based on a blood test called ferritin. Low folate was rare, affecting less than 1% of children.
When researchers looked at what children were eating, they found that kids were only eating about 69% of the calories they needed each day. Their vitamin D intake was especially low, at only 12% of what’s recommended. Iron intake was better at 78% of recommendations, and folate intake was 63% of recommendations.
Interestingly, children who were heavier did not necessarily have better vitamin levels. In fact, weight and vitamin levels didn’t connect strongly to each other. A child could be overweight but still have vitamin D deficiency, or be thin but have adequate vitamins.
The study found that body fat percentage matched closely with BMI (body mass index), which is a measure of weight for height. This means that BMI is a reasonably good way to estimate how much body fat a child has. However, this doesn’t help predict vitamin levels. The researchers also noted that the group had a mix of growth problems, with some children too short and others too tall, suggesting that autism may affect growth in different ways for different children.
Earlier research has shown that children with autism often have eating problems and may not get enough nutrients. This study confirms those findings and adds new information by measuring actual vitamin levels in blood. Previous studies mostly looked at weight or diet separately, but this study looked at both together. The high rate of vitamin D deficiency matches what researchers have found in other countries, suggesting this is a widespread problem for children with autism.
This study has several important limitations. First, it only included children from one autism center in Saudi Arabia, so the results might not apply to children in other countries or regions. Second, about 90% of participants were boys, so we don’t know if girls with autism have the same nutrition problems. Third, only 46% of families provided detailed food records, so the diet information is incomplete. Fourth, the study was done at one point in time, so we can’t tell if these problems are getting better or worse over time. Finally, the study didn’t look at why children had these nutrition problems, such as whether it was due to picky eating, difficulty chewing, or other factors related to autism.
The Bottom Line
Based on this research, children with autism should have regular nutrition check-ups that include blood tests for vitamin D, iron, and folate, not just weight checks. Vitamin D supplementation should be considered for most children with autism, especially in regions with less sunlight. Families should work with nutritionists to help children eat enough calories and a variety of foods. These recommendations have moderate confidence because they come from one study, but they match what other research suggests.
Parents and caregivers of children with autism should pay attention to these findings. Doctors who care for children with autism should consider testing for vitamin deficiencies. Teachers and school staff who work with children with autism should know that nutrition problems are common. Children with autism who have picky eating or sensory food issues are at highest risk. These findings may be less relevant for children with autism who eat a wide variety of foods without difficulty.
Vitamin D deficiency takes weeks to months to develop and weeks to months to improve with supplementation. Iron deficiency develops slowly over months. Parents should expect to see improvements in energy and mood within 4 to 8 weeks of starting vitamin supplements, though blood levels may take longer to normalize. Growth improvements take months to years to become visible.
Frequently Asked Questions
Do children with autism have more vitamin D problems than other kids?
Research shows that 57% of children with autism in this study had vitamin D deficiency compared to about 20-30% in general child populations. Children with autism may have higher rates because of limited sun exposure, picky eating, or digestive issues related to autism.
Can you tell if a child with autism has vitamin problems just by looking at their weight?
No. This study found that weight and vitamin levels don’t connect strongly. A child could be overweight but vitamin deficient, or normal weight but lacking vitamins. Blood tests are needed to know for sure.
What should parents do if their child with autism isn’t eating enough?
Work with a nutritionist who understands autism to find foods the child will eat. Consider vitamin supplements, especially vitamin D. Track calories and nutrients. Talk to your doctor about whether your child needs blood tests for vitamin levels.
How common is vitamin D deficiency in children with autism?
This study found that 89% of children with autism had either vitamin D deficiency or insufficiency. This is much higher than in children without autism, making vitamin D testing important for all children with autism.
Should all children with autism take vitamin D supplements?
Based on this research, most children with autism should have their vitamin D levels tested. If levels are low, supplements are recommended. Talk to your child’s doctor about the right dose and whether testing is needed before starting supplements.
Want to Apply This Research?
- Track daily vitamin D intake in micrograms and vitamin D supplement doses. Set a reminder to take supplements at the same time each day. Log weekly energy levels and mood on a scale of 1 to 10 to see if supplements help.
- Use the app to plan meals that include vitamin D-rich foods like fortified milk, fatty fish, and egg yolks. Set daily calorie goals based on the child’s age and activity level. Create a food diary to identify which foods the child will eat and which ones to avoid.
- Check in monthly with a doctor to review supplement adherence and any changes in appetite or energy. Request blood tests for vitamin D, iron, and folate every 3 to 6 months to track improvement. Use the app to record any changes in weight, height, or how the child feels.
This article summarizes research findings and is not medical advice. Children with autism should have nutrition assessments and blood tests performed by qualified healthcare providers. Do not start supplements or make major diet changes without consulting your child’s doctor. Vitamin D deficiency and other nutrition problems require professional diagnosis and treatment. Results from this study may not apply to all children with autism in all regions.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.