Researchers in Eastern China studied over 1,800 children aged 3 to 14 years to measure their levels of five fat-soluble vitamins: A, D, E, K1, and K2. These vitamins support bone health, immunity, and development.
The study, published in Frontiers in Pediatrics, found significant gaps in two key nutrients across the children tested.
Vitamin D and K2 deficiencies are surprisingly common
Vitamin D deficiency affected 13.6% of boys and 22.4% of girls in the study. Vitamin K2 deficiency was even more widespread, affecting 36% of boys and nearly 40% of girls. These are substantial numbers—roughly one in four girls lacked adequate vitamin D, and more than one in three children of both genders were short on vitamin K2.
Deficiencies follow a seasonal pattern
The study revealed that vitamin deficiencies weren't constant year-round. Vitamin D levels dropped significantly during winter and spring, with girls aged 9 to 12 most affected. Vitamin K2 deficiency peaked in boys aged 8 to 9 during spring. This pattern matters because it suggests children may need extra nutritional support during specific seasons, not just across the board.
Vitamin K may connect to early puberty in girls
Girls with early puberty (precocious puberty) had notably lower levels of both vitamin K1 and K2 compared to girls developing at typical ages. The researchers emphasise this doesn't prove that low vitamin K causes early puberty—the link is a correlation, not proven cause-and-effect. However, it points to a possible metabolic connection worth exploring further.
The study was conducted in Eastern China, which has a subtropical climate. While findings from one region don't automatically apply everywhere, Singapore's similar climate and indoor-focused lifestyles (air-conditioned homes, schools, and cars) mean these results may be relevant for local families. Even in a tropical country with abundant sunshine, reduced outdoor time during certain seasons or exam periods could limit natural vitamin D production.
Supporting your child's nutrient intake year-round
- Watch for seasonal dips: during winter months or periods of increased indoor time, ask your child's doctor about vitamin D and K2 testing or supplements.
- Serve vitamin K-rich foods regularly: leafy greens, broccoli, and fermented foods support these nutrients without requiring supplementation.
- Balance sun safety with vitamin D: seek moderate outdoor time during cooler parts of the day, especially during exam-heavy seasons when children stay indoors more.