Vitamin D deficiency increases the risk of overweight and harmful inflammation

According to WHO, the number of overweight children has reached epidemic proportions. Overweight children risk being overweight as adults and develop hypertension, cardiovascular disease, type 2 diabetes, chronic inflammation, and other metabolic disturbances. Apparently, overweight individuals often lack vitamin D, a nutrient that is important for regulating weight, inflammation, and many metabolic processes. This was pointed out in an Italian study published in Nutrients, where the authors address vitamin D’s role in health and explain why so many overweight people are vitamin D-deficient.

Overweight children have great difficulty with losing weight in adult life. This is because the average number of fat cells in the body increases until the age of around 20, at which point it stabilizes. Overweight children and youngsters therefore have more fat cells than their normal-weight peers.
Once the overweight children and youngsters reach adulthood, weight loss will not affect the number of fat cells but only the amount of fat stored in these cells. It is therefore more difficult for someone to lose weight if they have been overweight as a child. Overweight people also have a greater risk of developing different metabolic disturbances that even affect insulin sensitivity and set the stage for chronic inflammation, elevated blood pressure, type 2 diabetes, and cardiovascular disease.
Numerous studies have demonstrated a link between vitamin D deficiency and an increased risk of cardiovascular disorders. Studies have also linked elevated levels of the Plasminogen Activator Inhibitor-1 (PAI-1) protein to an increased risk of insulin resistance, blood clots, and atherosclerosis. PAI-1 is found in many cells and in blood platelets.
In the new study, Italian scientists wanted to look closer at the relation between blood levels of vitamin D, PAI-1, insulin sensitivity, and inflammation. They measured blood levels of vitamin D, PAI-1, and other parameters in 259 Italian children, who were either overweight or obese. The children were between two and 18 years of age and were recruited from a large Italian cohort study called Nutritional Education Program of the Bambino Gesú Children’s Hospital and Research Institute of Rome. The researchers also included 80 children and youngsters of normal body weight as a control group. Their blood levels of vitamin D, PAI-1, and other parameters were also measured.
When comparing the two groups, the scientists found that overweight children were more likely to be vitamin D-deficient and showed an increased tendency towards increased levels of PAI-1, a higher rate of insulin resistance, and elevated inflammation markers in the blood.
Based on their findings, the scientists conclude that overweight children and youngsters are at increased risk of having low vitamin D levels and elevated levels of PAI-1, which increases their risk of cardiovascular diseases and blood clots.

How does vitamin D affect blood sugar levels, weight control, and cardiovascular health?

Most overweight people have difficulty with maintaining stable blood sugar levels, which is why they snack in between meals, causing the excess calories to be stored as fat and making their weight go up. Overweight is also linked to insulin resistance where the uptake of glucose in cells is impaired. This can eventually result in metabolic syndrome and type 2 diabetes that is spreading like a bushfire.
Active vitamin D is considered a steroid hormone that affects most cells in the body by way of their vitamin D receptors. This also goes for the insulin-producing beta cells in the pancreas. There are also vitamin D receptors in the hypothalamus, the part of the brain that controls our appetite and metabolism. Scientists have even found a link between vitamin D and the release of leptin from fatty tissue. Leptin is a so-called satiety hormone.
Vitamin D regulates inflammation. Overweight people often suffer from chronic low-grade inflammation because their fatty tissue produces too many pro-inflammatory cytokines. Insulin resistance and chronic inflammation are known to set the stage for oxidative stress, atherosclerosis, and other cardiovascular diseases, which is why vitamin D is important in so many ways.
According to the new study, vitamin D even helps regulate levels of PAI-1, which is also important because elevated levels of this protein increase the risk of atherosclerosis and blood clots. Studies suggest that overweight people and diabetics have an increased need for vitamin D.

Why do overweight people often lack vitamin D, and why do they have an increased need for the nutrient?

Around one billion people worldwide are believed to lack vitamin D, primarily because of modern living and too little sun exposure. Studies have shown a link between overweight and vitamin D deficiency, which makes it difficult to lose weight, in addition.
The jury is still out on the question if overweight people are more likely than others to have low vitamin D levels in their blood. Vitamin D is a lipid-soluble nutrient, and it is therefore theorized that overweight individuals store more vitamin D in their fatty tissue and have lower quantities of the vitamin in their blood. We only get limited amounts of vitamin D from the food we eat. The problem is only made worse by the fact that many people have unhealthy eating habits and don’t eat the good vitamin D sources such as oily fish, cod roe, eggs, and high-fat dairy products. Many people who are overweight get too little sunshine, and the winter sun is not strong enough to enable vitamin D synthesis in our skin. Moreover, the form of vitamin D that we humans synthesize in the skin must be converted by the liver to 25(OH)D (25-hydroxy-vitamin D), which is the form of vitamin D that is measured in blood tests. Afterwards, 25(OH)D is converted into the active steroid form of vitamin D (1,25-dihydroxy-vitamin D), and this process is handled by the kidneys and other tissues. Interestingly, many overweight people and individuals suffering from metabolic syndrome have difficulty with activating vitamin D and therefore have an increased need for the nutrient.
Also, we need magnesium to activate vitamin D, and many people don’t get enough magnesium from their daily diet.

Vitamin D supplements and optimal nutrient utilization

When health authorities make guidelines for recommended vitamin D intake, they fail to take into account that overweight people have an increased need. The European Food Safety Authority (EFSA) has established the following safe upper intake levels for vitamin D: infants (25 micrograms/day), children aged six months to 10 years (50 micrograms/day), and children from the age of 11 years plus adults (100 micrograms/day). Because vitamin D is lipid-soluble we get the best effect by taking the nutrient in some type of oil in capsules. Make sure to get enough magnesium so the body can activate vitamin D.

References:

Giovina Di Felice et al. Plasminogen Activator Inhibitor-1 and Vitamin D Association in Overweight and Obese Pediatric Population. Nutrients 2023.

Deirdre K. Tobias et L. Association of Body Weight with Response to Vitamin D Supplementation and Metabolism. JAMA Network Open, 2023

Scott LaFee. Vitamin D Deficiency Linked to Greater Risk of Diabetes. UC San Diego Health. April 2018

Anne Marie Uwitonze, Mohammed S Razzaque. Role of Magnesium in Vitamin D Activation and Function. J Am Osteopath Assoc. 2018