Vitamin D builds your bones and keeps your gut sealed, among many other essential functions − but many children are deficient
- Written by Jacqueline Hernandez, Assistant Professor of Dietetics and Nutrition, Florida International University
You’ve likely heard about vitamin D’s important role in maintaining strong bones and teeth[1]. But it also plays several other important roles to keep your body healthy – including the function of your gut.
As part of our research[2] on how a dietary fiber supplement[3] affects bone mass in children and adolescents, the MetA-Bone Trial[4], we are also studying gut health[5].
For this study, we recruited 213 children and adolescents from South Florida, primarily Hispanics, though some were Black. Before having them start taking the fiber supplement, we measured their vitamin D levels to ensure they had adequate amounts. Surprisingly, we found that 68% of these children[6] had suboptimal vitamin D levels.
Considering South Florida is an area with plenty of sunshine year-round[7], this was both startling and concerning. While vitamin D can be obtained from foods, most people in the U.S. get this vitamin primarily from skin exposure to sunlight[8]. For youth approaching or experiencing puberty – a period of profound physiological changes, including rapid changes in bone mass[9] – vitamin D deficiency could lead to several health issues.
Connection between vitamin D and health
Vitamin D is involved in so many bodily functions because there are vitamin D receptors in different organs[12]. These receptors act like docking stations for vitamin D to bind to and trigger different effects in the skin, intestine, bone, parathyroid gland, immune system and pancreas, among others.
Vitamin D regulates calcium levels[13] in the body, which is key for not only building and maintaining bone mass but also the basic functioning of the nervous system.
Vitamin D also stimulates cell differentiation[14], a process in which cells become specialized to carry out specific functions. It is also essential to insulin secretion[15] to control blood sugar levels, blood pressure regulation[16], muscle repair and regeneration[17], immune function[18] and nutrient absorption[19], among many other functions.
Vitamin D and gut health
The vitamin D receptors in your gut improve calcium absorption[20] and strengthen your intestinal barrier[21].
The intestinal barrier[22] is a layered wall that allows your gut to absorb nutrients and keep out harmful bacteria. This wall is composed of intestinal cells and proteins called tight junctions[23] that act like bricks sealing these cells together. Tight junctions play an important role in maintaining the structure of your intestinal barrier.
Vitamin D receptors help your gut produce tight junctions[25] to maintain your intestinal barrier. Research suggests that vitamin D deficiency reduces production of the receptors[26] the nutrient binds to, subsequently reducing the seal of the intestinal wall. This weakening of the gut barrier may allow substances from the intestine to pass into the blood[27], causing inflammation. Disruption of the intestinal barrier is linked to many diseases[28], including liver disease, Type 1 diabetes, obesity and gastrointestinal conditions such as celiac disease, inflammatory bowel disease and colon cancer.
After discovering that so many of the participants in our MetA-Bone Trial had suboptimal vitamin D levels, we became interested in understanding how this nutrient might be affecting their gut health. For this, we also measured the strength of their intestinal barrier and associated this to their vitamin D levels in blood.
We found that children with suboptimal vitamin D levels had a higher risk of damaging their intestinal barrier[29] compared with children with optimal vitamin D levels. This finding suggests that even in healthy children, suboptimal levels of vitamin D may compromise the gut and potentially increase the risk of developing chronic diseases at an early age.
Getting enough vitamin D
Vitamin D deficiency is highly prevalent in the U.S. and around the world[30]. Roughly 15.4% of children and adolescents[31] in the U.S. were vitamin D deficient in 2017. While vitamin D deficiency has slightly decreased over time in the general U.S. population, it remains high among teens[32], especially children with darker skin.
How can you ensure you are getting enough of this important nutrient?
Only a few foods naturally contain vitamin D[33]. For example, vitamin D is naturally found in fatty fish – such as trout, salmon, cod and tuna – egg yolks and mushrooms. Vitamin D can also be found in many fortified foods[34], such as dairy products like milk and cheese, plant-based milks, breakfast cereals, some orange juice brands and infant formulas. Dietary supplements are also good sources of vitamin D.
Some foods are good sources of vitamin D.
happy_lark/iStock via Getty Images Plus[35]
For most people in the U.S., Sun exposure is their main source of vitamin D[36]. However, how much Sun exposure you need depends on several factors, such as the melanin content of your skin[37]. Melanin is a pigment that protects your skin from ultraviolet radiation. People with more melanin – and therefore darker skin – produce less vitamin D from Sun exposure than those with less melanin and may thus require longer Sun exposure to meet minimum requirements.
Since excessive ultraviolet radiation is associated with skin cancer[38], clinicians typically recommend you meet your vitamin D requirements through foods and beverages. For healthy children and adults, the recommended dietary allowance of vitamin D[39] is 600 IU, with an age-based upper limit of no more than 1,000 to 4,000 IU. You can usually meet this through a healthy diet[40] that includes a variety of whole and unprocessed foods.
Researchers continue to uncover the extensive benefits of vitamin D in the body, supporting its indispensable role in nutrition and health. For growing children and adolescents, enough vitamin D is important for healthy development.
References
- ^ maintaining strong bones and teeth (ods.od.nih.gov)
- ^ our research (metabone.fiu.edu)
- ^ a dietary fiber supplement (stempel.fiu.edu)
- ^ the MetA-Bone Trial (doi.org)
- ^ gut health (stempel.fiu.edu)
- ^ 68% of these children (doi.org)
- ^ plenty of sunshine year-round (climatecenter.fsu.edu)
- ^ skin exposure to sunlight (www.ncbi.nlm.nih.gov)
- ^ rapid changes in bone mass (pubmed.ncbi.nlm.nih.gov)
- ^ Hrant Khachatryan/Unsplash (unsplash.com)
- ^ CC BY-SA (creativecommons.org)
- ^ in different organs (doi.org)
- ^ regulates calcium levels (www.ncbi.nlm.nih.gov)
- ^ cell differentiation (doi.org)
- ^ insulin secretion (lpi.oregonstate.edu)
- ^ blood pressure regulation (lpi.oregonstate.edu)
- ^ muscle repair and regeneration (doi.org)
- ^ immune function (lpi.oregonstate.edu)
- ^ nutrient absorption (www.ncbi.nlm.nih.gov)
- ^ improve calcium absorption (doi.org)
- ^ strengthen your intestinal barrier (doi.org)
- ^ intestinal barrier (doi.org)
- ^ tight junctions (doi.org)
- ^ VectorMine/iStock via Getty Images Plus (www.gettyimages.com)
- ^ produce tight junctions (doi.org)
- ^ reduces production of the receptors (doi.org)
- ^ substances from the intestine to pass into the blood (doi.org)
- ^ linked to many diseases (doi.org)
- ^ higher risk of damaging their intestinal barrier (doi.org)
- ^ U.S. and around the world (doi.org)
- ^ 15.4% of children and adolescents (doi.org)
- ^ high among teens (doi.org)
- ^ naturally contain vitamin D (doi.org)
- ^ fortified foods (ods.od.nih.gov)
- ^ happy_lark/iStock via Getty Images Plus (www.gettyimages.com)
- ^ main source of vitamin D (theconversation.com)
- ^ melanin content of your skin (www.ncbi.nlm.nih.gov)
- ^ skin cancer (www.cancer.org)
- ^ recommended dietary allowance of vitamin D (ods.od.nih.gov)
- ^ healthy diet (www.dietaryguidelines.gov)
Authors: Jacqueline Hernandez, Assistant Professor of Dietetics and Nutrition, Florida International University
