Scientists used genetic data from over 380,000 people to study whether vitamin D affects how tall we grow. They found that people with higher vitamin D levels in their blood tend to be slightly taller as adults. However, the effect is small - vitamin D alone won’t make someone dramatically taller. The researchers used a special method that looks at genes instead of just asking people about their habits, which makes the results more reliable than previous studies.

The Quick Take

  • What they studied: Whether having higher vitamin D levels in your blood causes you to grow taller as an adult
  • Who participated: Over 380,000 European and Finnish adults whose genetic information was analyzed
  • Key finding: People with higher vitamin D levels were slightly taller, but the effect was small - about 0.046 standard deviations per unit increase
  • What it means for you: Getting enough vitamin D may support healthy growth, but taking extra supplements won’t make you significantly taller if you already have normal levels

The Research Details

This study used a method called Mendelian randomization, which is like nature’s own experiment. Instead of giving people vitamin D supplements and measuring their height, researchers looked at genetic variations that naturally cause some people to have higher or lower vitamin D levels. They then checked if people with ‘high vitamin D genes’ were also taller. This approach avoids many problems with traditional studies, like people forgetting to take supplements or other lifestyle factors getting in the way.

This genetic approach is important because it can show cause and effect more clearly than regular observational studies. When researchers just compare tall people to short people, they can’t tell if vitamin D made them taller, or if taller people just happen to have more vitamin D for other reasons.

The study used data from very large groups of people (over 380,000 total) and applied multiple statistical methods to check their results. They also tested whether other factors might be influencing their findings and found no evidence of this.

What the Results Show

The main finding was that genetically higher vitamin D levels were linked to increased adult height. For every standard deviation increase in vitamin D levels, people were about 0.046 standard deviations taller. While this sounds technical, it means the effect exists but is relatively small. The researchers were confident in this result because it showed up consistently across different statistical methods and had a very low probability of being due to chance (P = 1.53 × 10-5). Importantly, when they looked at the reverse direction - whether being taller causes higher vitamin D levels - they found no evidence for this.

The sensitivity analyses showed no signs that other genetic factors were interfering with the results. This means the connection between vitamin D and height appears to be direct rather than caused by some other genetic trait that affects both.

These genetic findings support what some previous randomized controlled trials have suggested about vitamin D and growth. However, this study provides stronger evidence for causation because it uses genetic data rather than relying on people to take supplements consistently.

The study only included people of European and Finnish ancestry, so the results might not apply to other populations. Also, while the effect is real, it’s quite small, meaning vitamin D is just one of many factors that determine adult height.

The Bottom Line

Ensure you’re getting adequate vitamin D through sunlight, food, or supplements as recommended by health guidelines, especially during childhood and adolescence when growth occurs. However, don’t expect dramatic height increases from vitamin D supplementation alone.

Parents of growing children and adolescents should pay attention to vitamin D status. Adults who are already fully grown won’t get taller from vitamin D, but maintaining adequate levels is still important for bone health.

Any effects on height would occur during periods of active growth (childhood and adolescence). Adults won’t see height changes from improving vitamin D status.

Want to Apply This Research?

  • Track daily vitamin D intake from food sources, supplements, and estimated sun exposure time
  • Set reminders to spend 10-15 minutes in sunlight daily or take vitamin D supplements as recommended by your healthcare provider
  • Log vitamin D-rich foods (fatty fish, fortified milk, eggs) and supplement intake, with periodic blood level checks if recommended by your doctor

This research shows associations in genetic data and should not replace medical advice. Consult your healthcare provider before starting any supplement regimen, especially for children. Vitamin D needs vary by individual, age, and geographic location.