Researchers in Turkey studied 418 children and teens (ages 6-18) who were overweight or obese to understand how vitamin D, body weight, and insulin (a hormone that controls blood sugar) are connected. They found that kids going through puberty had more vitamin D deficiency and higher insulin resistance than younger children. The study suggests that vitamin D deficiency may be linked to insulin resistance in overweight and obese young people. While these findings are interesting, the researchers note that larger, longer studies are needed to confirm these results and understand exactly how vitamin D affects growing bodies.

The Quick Take

  • What they studied: How vitamin D levels, obesity, and insulin resistance (a condition where the body doesn’t respond properly to insulin) are related in overweight and obese children and teenagers
  • Who participated: 418 young people aged 6-18 years old (average age about 12) who were diagnosed as overweight or obese. About 38% were before puberty and 62% were going through or had gone through puberty
  • Key finding: Teenagers going through puberty with low vitamin D levels had higher insulin resistance. About 51% of teens in puberty had low vitamin D, compared to 44% of younger children. Interestingly, insulin resistance was actually more common in younger children (37%) than in teens (26%)
  • What it means for you: If you’re an overweight or obese young person, especially one going through puberty, getting enough vitamin D may be important for your body’s ability to handle blood sugar properly. However, this is one study with a limited number of participants, so talk to your doctor before making changes based on this research

The Research Details

This was a retrospective study, which means researchers looked back at medical records from 2020-2022 to gather information. They collected data on 418 young people aged 6-18 who had been diagnosed with obesity or being overweight. The researchers recorded information like age, gender, height, weight, and blood test results that measured vitamin D levels and insulin resistance. They compared results between younger children (before puberty) and teenagers (during or after puberty) to see if age and development stage made a difference.

The researchers used standard medical measurements to evaluate the data. They used WHO (World Health Organization) growth charts to determine if children were overweight or obese based on their age. They measured vitamin D using a blood test called 25(OH) vitamin D, and they measured insulin resistance using a calculation called HOMA-IR, which shows how well the body is responding to insulin.

By comparing the two age groups, the researchers could see whether the relationships between vitamin D, weight, and insulin resistance changed as children went through puberty.

This research approach is important because it looks at a real-world question: as kids grow and go through puberty, do their vitamin D levels and insulin resistance change? By comparing younger children to teenagers, the researchers could see if puberty itself plays a role. Understanding these connections is valuable because insulin resistance can lead to serious health problems like type 2 diabetes later in life, and vitamin D is known to be important for many body functions.

This study has some strengths and some limitations to keep in mind. The strength is that it included a decent-sized group (418 participants) and used standard medical measurements. However, because it’s a retrospective study looking at past records, researchers couldn’t control all the factors that might affect the results. The study was done in Turkey with one group of patients, so the results might not apply exactly the same way to other populations. The researchers themselves noted that this is a limited study and that larger, longer studies are needed to confirm the findings.

What the Results Show

The study found that vitamin D deficiency was common in both age groups but more common in teenagers going through puberty. About 44% of younger children had low vitamin D, while 51% of teenagers had low vitamin D. This suggests that as kids go through puberty, they’re more likely to have low vitamin D levels.

The researchers also found an important connection: in teenagers going through puberty, as vitamin D levels dropped, insulin resistance increased. This relationship was statistically significant, meaning it’s unlikely to have happened by chance. In other words, teenagers with the lowest vitamin D levels tended to have the highest insulin resistance.

Another interesting finding was that vitamin D levels were connected to other health markers. Lower vitamin D was associated with higher BMI (body mass index, a measure of weight relative to height) and higher insulin resistance. However, vitamin D was connected to lower HDL cholesterol (the ‘good’ cholesterol that protects your heart).

The researchers noted that insulin resistance was actually more common in younger children (37%) than in teenagers (26%), which was somewhat surprising and suggests that the relationship between age, puberty, and insulin resistance is complex.

The study found that vitamin D deficiency was linked to higher BMI for age, meaning children with lower vitamin D tended to weigh more relative to their height. The connection between vitamin D and HDL cholesterol (good cholesterol) was also notable, though the direction of this relationship requires further study. These secondary findings suggest that vitamin D may play a broader role in metabolic health beyond just insulin resistance.

This research fits with existing knowledge that vitamin D is important for metabolic health and that insulin resistance is a growing problem in overweight and obese young people. Previous studies have suggested connections between vitamin D and insulin resistance, but results have been mixed. This study adds to that body of research by specifically looking at how puberty might affect these relationships. The finding that vitamin D deficiency is more common in teenagers than younger children is consistent with other research showing that vitamin D levels often drop during the teenage years.

The researchers were clear about several limitations. First, this was a retrospective study using old medical records, so they couldn’t control for all the factors that might affect vitamin D and insulin resistance, like sun exposure, diet, physical activity, or supplements. Second, the study only included 418 participants from Turkey, so the results might not apply the same way to other countries or populations with different genetics, climates, or lifestyles. Third, because this is a single study looking at data from one time period, we can’t say for certain that low vitamin D causes insulin resistance—only that they’re connected. Finally, the researchers noted that larger, longer studies are needed to confirm these findings and understand the cause-and-effect relationships.

The Bottom Line

Based on this research, overweight and obese young people, especially those going through puberty, should consider having their vitamin D levels checked by a doctor. If vitamin D is low, supplementation or increased sun exposure (with appropriate sun protection) may be beneficial. However, this recommendation comes with moderate confidence because this is a single study with limitations. Always consult with a healthcare provider before starting supplements or making major changes to diet or lifestyle. General recommendations for vitamin D intake should be followed based on age and individual health status.

This research is most relevant to overweight and obese children and teenagers, particularly those going through puberty. Parents and guardians of young people in these categories should be aware of the potential importance of vitamin D. Healthcare providers caring for overweight or obese youth should consider checking vitamin D levels as part of routine care. This research is less directly applicable to normal-weight children or adults, though vitamin D remains important for everyone’s health.

If vitamin D deficiency is identified and treated, improvements in insulin resistance might take weeks to months to become apparent. However, this study doesn’t provide specific information about how quickly vitamin D supplementation improves insulin resistance. Long-term benefits would likely develop over months to years of maintaining adequate vitamin D levels. It’s important to have realistic expectations and work with a healthcare provider to monitor progress.

Want to Apply This Research?

  • Track daily vitamin D intake (through food, supplements, or sun exposure time) and record it in the app. Also track fasting blood sugar levels or HOMA-IR values if available from doctor visits, along with the date of measurement. This creates a record to share with your healthcare provider.
  • Set a daily reminder to take a vitamin D supplement if prescribed by your doctor, or to spend 10-15 minutes in sunlight (with appropriate sun protection). Log this activity in the app to build consistency and see your progress over time.
  • Schedule regular check-ins with your doctor every 3-6 months to recheck vitamin D levels and insulin resistance markers. Use the app to record these test results and any changes in symptoms or energy levels. Track weight and BMI measurements monthly to see if vitamin D supplementation correlates with any changes in these metrics over time.

This research summary is for educational purposes only and should not be used as a substitute for professional medical advice. The study has limitations and represents one research effort that requires confirmation through larger studies. If you or a young person in your care is overweight or obese, or if you’re concerned about vitamin D levels or insulin resistance, please consult with a qualified healthcare provider for proper evaluation, testing, and personalized recommendations. Do not start supplements or make significant dietary changes without first discussing with a doctor. Individual health needs vary, and what applies to the study population may not apply to everyone.