By Andreia Correia, DipCNM.
This article will guide you through:
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- Vitamin D: What It Is and How It Works in the Body
- Vitamin D and mental health
- Vitamin D and sleep
- What are the signs of deficiency
- Main dietary sources
- Vitamin D supplementation
Understanding Vitamin D: What It Is and How It Works in the Body
Vitamin D, often called the “sunshine vitamin,” is a fat-soluble vitamin essential for various bodily functions. Being fat-soluble means it dissolves in fat and is stored in the body’s fatty tissues and liver. This allows the body to release it when needed, like during the winter months when sunlight is limited [1, 3].
Vitamin D comes in two main forms: D2 (ergocalciferol) and D3 (cholecalciferol). These forms are found in foods and supplements and differ slightly in their chemical structure. Both are well absorbed in the small intestine, with fat in the diet helping the process, although absorption can still happen without it. Interestingly, factors like aging or obesity don’t affect how well vitamin D is absorbed [1].
Once vitamin D enters your body—whether through sunlight, food, or supplements—it goes through a two-step process to become active. First, the liver converts it into a form called calcidiol. Then, the kidneys turn calcidiol into calcitriol, the active form of vitamin D. This active form plays a crucial role in helping the body absorb calcium and phosphorus, which are vital for strong bones and teeth [2, 3].
Beyond bone health, vitamin D supports the immune system, reduces inflammation, and helps maintain healthy muscle and nerve functions. Its ability to be stored in the body’s fat ensures a steady supply throughout the year, even when sunlight is scarce [1, 3].
Understanding how vitamin D works shows just how important it is for your child’s overall health, mental well-being, and sleep—topics we’ll explore further.
Vitamin D and Mental Health
Vitamin D is more than just a nutrient for physical health—it plays a vital role in supporting brain function and mental well-being. Acting as a brain-regulating steroid, vitamin D interacts with receptors in many brain regions. These receptors help reduce inflammation, protect against oxidative stress, and regulate cell growth. By doing so, vitamin D supports healthy brain development and function [4].
One of its most important roles is influencing serotonin and dopamine production, two neurotransmitters crucial for mood regulation, focus, and behavior. Research shows that low vitamin D levels have been linked to conditions like ADHD and autism spectrum disorder (ASD). For children with ADHD, lower vitamin D levels are associated with more than twice the risk of developing the condition compared to children with sufficient levels. Additionally, insufficient vitamin D during pregnancy can increase the likelihood of ADHD-like symptoms in children later in life [4, 5].
Studies have also explored the potential benefits of vitamin D supplementation. In children with ASD, supplementation did not significantly affect core symptoms like communication but did improve hyperactivity, a common co-occurring behavior in neurodevelopmental conditions. Similarly, vitamin D supports brain regions responsible for attention and impulse control, which may help reduce symptoms like inattention or impulsiveness in ADHD. While these findings are promising, they highlight the need for more research to establish causality [4, 5].
Ensuring adequate vitamin D intake through safe sun exposure, a balanced diet, or supplements may benefit overall health and potentially support mental well-being. This is especially important for children and pregnant women [4, 5].
Vitamin D and Sleep
Vitamin D plays a significant role in regulating sleep, with deficiencies linked to poorer sleep quality and certain sleep disorders. Research suggests that vitamin D influences the brain areas that control sleep and may regulate melatonin, a hormone essential for the sleep-wake cycle. Low levels of vitamin D have been associated with difficulties falling asleep, shorter sleep duration, and frequent nighttime awakenings [6].
A systematic review and meta-analysis examined the effects of vitamin D supplementation on sleep and found promising results. Studies showed that vitamin D supplementation significantly improved overall sleep quality, reducing sleep disturbances and the time it takes to fall asleep. Participants also experienced longer and more restful sleep [6].
However, the research also highlighted inconsistencies in the effect of vitamin D supplementation on specific sleep disorders, such as insomnia and restless legs syndrome. While some studies observed improvements in symptoms, others found no significant changes. These mixed findings suggest that the impact of vitamin D might vary based on factors like individual health, baseline vitamin D levels, and the dosage and duration of supplementation [6].
What are the signs of deficiency
Vitamin D deficiency can affect children in various ways, with symptoms ranging from subtle to severe. Common signs include fatigue, frequent illnesses, delayed growth, muscle weakness, and bone pain. These symptoms occur because vitamin D plays a critical role in calcium absorption, immune function, and overall bone and muscle health. Prolonged deficiency can lead to conditions like rickets, a disorder causing soft and weak bones in children.
In the UK, many children do not meet the recommended levels of essential nutrients, including vitamin D. The latest National Diet and Nutrition Survey (NDNS) highlights that 19% of children aged 11–18 have vitamin D levels below 25 nmol/L, the threshold associated with an increased risk of poor bone and musculoskeletal health. This number is significantly higher than the deficiency rates in younger children (2% in those aged 4–10), indicating a growing concern as children age. Vitamin D levels are particularly low during the winter months due to reduced sun exposure [7, 8, 10].
Additionally, the survey underlines broader nutritional gaps in the UK, with many children failing to achieve adequate levels of nutrients vital for brain development, such as folate. For instance, 17% of children aged 11–18 have red blood cell folate levels indicating risk of anemia [9, 10].
Parents and carers should look for signs such as persistent tiredness, frequent colds or infections, slow or stunted growth, muscle aches, or difficulty walking due to bone pain. In more severe cases, symptoms may include soft skull bones, leg deformities like bow legs, or irritability in younger children. Adolescents may report vague symptoms such as back, joint, or thigh pain, especially during physical activities like climbing stairs. Early detection is vital to prevent serious complications such as rickets, osteomalacia, or fractures [11].
Main dietary sources
Vitamin D can be obtained from three main sources: sunlight, food, and supplements.
Vitamin D is unique because it can be produced by the body through sunlight exposure, but it’s also found in some foods and supplements. The body produces vitamin D naturally when the skin is exposed to sunlight, specifically ultraviolet B (UVB) rays. Just 10–30 minutes of midday sun exposure a few times per week is often enough for most people to maintain adequate levels. However, factors such as cloudy weather, darker skin tones, sunscreen use, and limited daylight during winter months in countries like the UK can reduce the body’s ability to produce vitamin D this way [12].
While there are few natural food sources of vitamin D, oily fish such as salmon, mackerel, and sardines are excellent options. Other natural sources include egg yolks, red meat, liver, and mushrooms. Many foods are fortified with vitamin D, including some cereals, plant-based milks, spreads, and infant formulas [12, 13].
By combining these sources, parents and carers can ensure their children maintain healthy vitamin D levels, supporting strong bones, muscle function, and overall well-being.
Vitamin D supplementation
Vitamin D supplementation is a safe and effective way to address vitamin D deficiency, which is common among children and, as previously discussed, essential for many functions. Ensuring adequate levels can support mental well-being, improve behavioral challenges, and reduce emotional difficulties, especially in children with conditions like ADHD or ASD [14, 16].
Recommended dosages:
- Babies (0–12 months): 8.5–10 mcg daily unless consuming 500 ml or more of fortified formula milk.
- Children aged 1–4 years: 10 mcg daily throughout the year.
- Children over 4 years: 10 mcg daily during autumn and winter. Year-round supplementation is recommended for those with limited sun exposure, darker skin tones, or diets low in vitamin D [15].
For children with additional needs, like ADHD, higher doses (under medical supervision) have shown promising results, such as reduced emotional and peer problems and improved overall mental health [16].
Seasonal Supplementation
From late March to September, most children can obtain sufficient vitamin D from sunlight exposure. However, during autumn and winter, supplementation might be required, as sunlight levels are insufficient for vitamin D synthesis in many regions. Children with darker skin or limited outdoor activity may need year-round supplementation [15].
Consult Your Doctor or a Nutritional Therapist
To ensure safe and effective dosing, particularly for children with health conditions or those requiring high-dose supplementation, always seek professional advice [14, 16].
Conclusion
Vitamin D plays a remarkable role in our children’s health, from building strong bones to supporting mental well-being and improving sleep. This “sunshine vitamin” helps regulate mood, behavior, and attention, making it a valuable nutrient for overall development.
While the body can produce vitamin D through sunlight exposure, many children may not get enough—especially during autumn and winter or if they have limited outdoor activity. Thankfully, supplementation provides a simple and effective way to bridge this gap. By following recommended daily doses and prioritizing foods rich in vitamin D, parents can help their children thrive.
For children with specific needs, such as those with ADHD or autism, vitamin D supplementation can offer additional benefits. Research suggests it may improve emotional regulation, behavior, and overall mental health. However, it’s always best to consult a healthcare provider to tailor supplementation to your child’s unique needs.
By ensuring your child gets enough vitamin D, you’re giving them a solid foundation for both physical and mental health. Whether it’s through sunlight, diet, or supplements, this small effort can make a big difference. Here’s to happy, healthy kids thriving with the help of vitamin D!
References:
1. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
2. https://www.healthline.com/health/food-nutrition/benefits-vitamin-d
3.https://www.webmd.com/vitamins/ai/ingredientmono-929/vitamin-d
4. Li, B., Xu, Y., Zhang, X., et. al. (2020). The effect of vitamin D supplementation in treatment of children with autism spectrum disorder: a systematic review and meta-analysis of randomized controlled trials. Nutritional Neuroscience, 25(4), 835–845.
5. Khoshbakht Y, Bidaki R, Salehi-Abargouei A.(2018). Vitamin D Status and Attention Deficit Hyperactivity Disorder: A Systematic Review and Meta-Analysis of Observational Studies. Adv. Nutr., 9(1), 9-20.
6. Abboud M. (2022). Vitamin D Supplementation and Sleep: A Systematic Review and Meta-Analysis of Intervention Studies. Nutrients, 14(5), 1076.
7.https://www.gov.uk/government/statistics/ndns-results-from-years-9-to-11-2016-to-2017-and-2 018-to-2019/ndns-results-from-years-9-to-11-combined-statistical-summary
8. https://www.mrc-epid.cam.ac.uk/blog/2020/12/11/ndns-years-9-to-11/
9. https://www.bda.uk.com/resource/the-latest-from-the-national-diet-and-nutrition-survey.html
10.https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_dat a/file/943114/NDNS_UK_Y911_report.pdf
11.https://www.healthline.com/nutrition/vitamin-d-deficiency-in-kids-and-teens#deficiency-sympto ms
12. https://www.bda.uk.com/resource/vitamin-d.html
13.https://www.medicalnewstoday.com/articles/324590 14. Kittana, M., Ahmadani, A., Stojanovska, L., et al. (2022). The Role of Vitamin D Supplementation in Children with Autism Spectrum Disorder: A Narrative Review. Nutrients, 14, 26.
15. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/
16. Hemamy. M., Pahlavani. N., Amanollahi. A., et. al. (2021). The effect of vitamin D and magnesium supplementation on the mental health status of attention-deficit hyperactive children: a randomized controlled trial. BMC Pediatr., 21(1), 178. Erratum in: BMC Pediatr., 2021 May 12; 21(1), 230.