Obesity is a global epidemic and contributes to an estimated 2.8 million deaths per year worldwide. Higher levels of belly fat are associated with lower vitamin D levels in obese individuals, according to data presented recently at the European Society of Endocrinology annual meeting, ECE 2018. The study reports that vitamin D levels are lower in individuals with higher levels of belly fat. It also suggests that individuals – particularly the overweight with larger waistlines – should have their vitamin D levels checked to avoid any potentially health-damaging effects.
Vitamin D deficiency is typically associated with impaired bone health, but in recent years it has also been linked with higher risks of acute respiratory tract infections, auto-immune diseases and cardiovascular diseases. Low vitamin D levels could therefore have wide-ranging and undetected adverse effects, although more research is required to confirm the role of vitamin D in these conditions. A link between low vitamin D levels and obesity has previously been reported but whether this effect is more associated with the type and location of fat was undetermined.
The study, conducted by the VU University Medical Center and Leiden University Medical Center in the Netherlands, examined how the amount of total body fat and abdominal fat measured in participants of the Netherlands Epidemiology of Obesity study related to their vitamin D levels. After adjusting for a number of possible influencing factors, including chronic disease, alcohol intake and levels of physical activity, they found that the amounts of both total and abdominal fat were associated with lower vitamin D levels in women, although abdominal fat had a greater impact. However, in men abdominal fat and liver fat was associated with lower vitamin D levels. In all cases the greater the amount of belly fat, the lower the levels of detected vitamin D.
“Although we did not measure vitamin D deficiency in our study, the strong relationship between increasing amounts of abdominal fat and lower levels of vitamin D suggests that individuals with larger waistlines are at a greater risk of developing deficiency, and should consider having their vitamin D levels checked,” study colleague Rachida Rafiq said. The researchers now plan to investigate what may underlie this strong association between vitamin D levels and obesity – whether a lack of vitamin D is predisposing individuals to store fat or whether increased fat levels are decreasing vitamin D levels is not yet clear. However, this research points to a more important role for abdominal fat in the relationship, and a place to focus future studies on.
“Due to the observational nature of this study, we cannot draw a conclusion on the direction or cause of the association between obesity and vitamin D levels,” Rafiq added. “However, this strong association may point to a possible role for vitamin D in abdominal fat storage and function.”
Vitamin D And Diabetes
More than 27 million people in the United States are living with type-2 diabetes, according to the Centers for Disease Control and Prevention. As the population ages and a growing percentage of people become overweight or obese, that number is expected to increase. A study, published recently in Cell, reports that researchers from the Salk Institute have found a potential new approach for treating diabetes by protecting beta cells – the cells in the pancreas that produce, store and release the hormone insulin. When beta cells become dysfunctional, the body can’t make insulin to control blood sugar and levels of glucose can rise to dangerous or even fatal levels.
Vitamin D in cells and mouse models proved beneficial in treating damaged beta cells. It also provided new insights about gene regulation that could be applied to developing treatments for other diseases, including cancer. “We know that diabetes is a disease caused by inflammation,” says senior author Ronald Evans, a Howard Hughes Medical Institute investigator and holder of Salk’s March of Dimes Chair in Molecular and Developmental Biology. “In this study, we identified the vitamin D receptor as an important modulator of both inflammation and beta cell survival.”
Using beta cells created from embryonic stem cells, the investigators were able to identify a compound – iBRD9 – that appeared to enhance the activation of the vitamin D receptor when it was combined with vitamin D to improve the survival of beta cells. The team accomplished this by conducting a screening test to look for compounds that improved the survival of beta cells in a dish. They then tested the combination in a mouse model of diabetes and showed that it could bring glucose back to normal levels in the animals.
“This study started out by looking at the role of vitamin D in beta cells,” says Zong Wei, a research associate in Salk’s Gene Expression Laboratory and the study’s first author. “Epidemiological studies in patients have suggested a correlation between high vitamin D concentrations in the blood and a lower risk of diabetes, but the underlying mechanism was not well understood. It’s been hard to protect beta cells with the vitamin alone. We now have some ideas about how we might be able to take advantage of this connection.”
Combining the new compound with vitamin D allowed certain protective genes to be expressed at much higher levels than they are in diseased cells. The underlying process has to do with transcription – the way that genes are translated into proteins. “Activating the vitamin D receptor can trigger the anti-inflammatory function of genes to help cells survive under stressed conditions,” says Michael Downes, a Salk senior staff scientist and co-corresponding author. “By using a screening system that we developed in the lab, we’ve been able to identify an important piece of that puzzle that allows for super-activation of the vitamin D pathway.”
The researchers feel that the discovery’s implications can have far-reaching implications. It identifies a basic mechanism that can be translated into drugging many different targets in the clinic. “In this study, we looked at diabetes, but because this is an important receptor and it could potentially be universal for any treatments where you need to boost the effect of vitamin D,” adds Ruth Yu, a Salk staff researcher and one of the study’s authors. “For example, we are especially interested in looking at it in pancreatic cancer, which is a disease that our lab already studies.” The investigators say that, although the new compound did not appear to cause any side effects in the mice, further testing is needed before clinical trials can begin.
Can Vitamin D Improve Sunburn?
High doses of vitamin D taken one hour after sunburn significantly reduce skin redness, swelling, and inflammation, according to a study by Case Western Reserve University School of Medicine and University Hospitals Cleveland Medical Center. The results were published in the Journal of Investigative Dermatology.
In the study, 20 participants were randomized to receive a placebo pill or 50,000, 100,000, or 200,000 IU – international unit – of vitamin D one hour after a small UV – ultraviolet – lamp “sunburn” on their inner arm. Researchers followed up with the participants 24, 48, 72 hours and one week after the experiment and collected skin biopsies for further testing. Participants who consumed the highest doses of vitamin D had long-lasting benefits including less skin inflammation 48 hours after the burn. Participants with the highest blood levels of vitamin D also had less skin redness and a jump in gene activity related to skin barrier repair.
“We found benefits from vitamin D were dose-dependent,” says Kurt Lu, MD, senior author on the study and Assistant Professor of Dermatology at Case Western Reserve University School of Medicine and University Hospitals Cleveland Medical Center. “We hypothesize that vitamin D helps promote protective barriers in the skin by rapidly reducing inflammation. What we did not expect was that at a certain dose, vitamin D not only was capable of suppressing inflammation, it was also activating skin repair genes.”
The trial is the first to describe acute anti-inflammatory benefits from taking vitamin D. According to the authors, despite widespread attention given to vitamin D deficiency, “there is a lack of evidence demonstrating that intervention with vitamin D is capable of resolving acute inflammation.” By measuring gene activity in the biopsies, the researchers also uncovered a potential mechanism behind how vitamin D aids skin repair. The results suggest vitamin D increases skin levels of an anti-inflammatory enzyme, arginase-1. The enzyme enhances tissue repair after damage and helps activate other anti-inflammatory proteins.
The trial tested very high doses of vitamin D that far exceed daily allowances. The Food and Drug Administration’s recommended adult daily allowance for vitamin D is 400 IU. “I would not recommend at this moment that people start taking vitamin D after sunburn based on this study alone,” Lu added. “But, the results are promising and worthy of further study.” The researchers plan additional studies that could inform treatment plans for burn patients.
Vitamin D Deficiency And Cardiovascular Disease
In overweight and obese children and adolescents, vitamin D deficiency is associated with early markers of cardiovascular disease, according to research results presented at the annual scientific meeting of the Endocrine Society last year. “Pediatric obesity affects 17 percent of infants, children, and adolescents ages two to 19 in the United States, and obesity is a risk factor for vitamin D deficiency,” said lead author Marisa Censani, M.D., pediatric endocrinologist and director of the Pediatric Obesity Program in the Division of Pediatric Endocrinology at New York Presbyterian Hospital/Weill Cornell Medicine in New York, N.Y.
These findings suggest that vitamin D deficiency may have negative effects on specific lipid markers with an increase in cardiovascular risk among children and adolescents. “This research is newsworthy because this is one of the first studies to assess the relationship of vitamin D deficiency to both lipoprotein ratios and non-high density lipoprotein (non-HDL) cholesterol, specific lipid markers impacting cardiovascular risk during childhood, in children and adolescents with obesity/overweight,” Censani noted.
The researchers reviewed the medical records, including vitamin D levels, of children and adolescents between six and 17 years of age who were evaluated at the pediatric endocrinology outpatient clinics at Weill Cornell Medicine over a two-year period. Overall, 178 of 332 patients met criteria for overweight and obesity: Body Mass Index (BMI) above the 85th percentile; and 60 patients with BMI above the 85th percentile had fasting lipid test results available. Total cholesterol, triglycerides, HDL, low-density lipoprotein (LDL), and non-HDL cholesterol were collected; and total cholesterol/HDL and triglyceride/HDL ratios were calculated.
Vitamin D deficiency was found to be significantly associated with an increase in atherogenic lipids and markers of early cardiovascular disease. Total cholesterol, triglycerides, LDL, non-HDL cholesterol, as well as total cholesterol/HDL and triglyceride/HDL ratios, were all higher in vitamin D-deficient patients compared to patients without vitamin D deficiency. “These results support screening children and adolescents with overweight and obesity for vitamin D deficiency and the potential benefits of improving vitamin D status to reduce cardiometabolic risk,” Censani added.