“Men who received vitamin K supplementation had less progression in their insulin resistance by the end of the clinical trial,” said Sarah Booth, PhD, senior author and director of the Vitamin K Laboratory at the USDA HNRCA. “Conversely, we saw progression in insulin resistance in women who received vitamin K supplementation, and in the men or women who were not given vitamin K supplements.”
Among those given vitamin K, both men and women took daily multivitamins containing 500 micrograms of vitamin K, five times the Adequate Intake (AI) recommended by the Institute of Medicine’s Food and Nutrition Board, with instructions to maintain normal diets without any additional supplementation. They also received a calcium and vitamin D supplement. Men and women in the control group received no vitamin K supplementation but did receive the multivitamin and the calcium and vitamin D supplement. For the present study, insulin resistance was assessed by the homeostasis model (HOMA-IR). Additionally, participants’ blood glucose and blood insulin levels were measured following a minimum 10-hour fast. In addition to improved insulin resistance, the supplemented men had lower blood insulin levels compared to the unsupplemented men at the conclusion of the study.
Insulin is a hormone which plays a role in transporting sugar into cells so it can be converted into energy. A pre-cursor to diabetes, insulin resistance occurs when the body cannot use insulin properly, causing glucose to build up in the blood. People who are obese or overweight are prone to insulin resistance because excess fat can interfere with insulin function.
Writing in the November issue of Diabetes Care, the authors speculate that weight might explain why only the vitamin K supplemented men improved their insulin resistance. “In our study, there was a higher prevalence of obese or overweight women in the vitamin K supplementation group compared to the male supplementation group,” Booth said. “Vitamin K is stored in fat tissue. If there is excess fat, vitamin K may not be readily available to cells that require it to process glucose.”
Because there are few studies of vitamin K and insulin resistance, the authors encourage further investigation of their findings and alternative study designs. “The original purpose of the present study was to assess the effect of vitamin K1, or phylloquinone, supplementation on changes in bone mineral density and vascular calcification,” Booth said. “For instance, there is a way to achieve a more direct measure of insulin secretion than HOMA-IR. Also, our study is limited to caucasian adults. We acknowledge our findings may not apply to the general population.”
Although vitamin K supplements were used for the study, the authors say the study dosage is attainable by consuming a healthy diet. Foods considered good sources of vitamin K include brussels sprouts, broccoli, and dark, leafy greens, such as spinach and collards.
The authors received funding from the United States Department of Agriculture Agricultural Research Service, the National Institutes of Health, the American Heart Association, the Ministry of Education, Culture Sports and Technology in Japan and the American Diabetes Association
About Tufts University School of Nutrition
The Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University is the only independent school of nutrition in the United States. The school's eight centers, which focus on questions relating to famine, hunger, poverty, and communications, are renowned for the application of scientific research to national and international policy. For two decades, the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University has studied the relationship between good nutrition and good health in aging populations. Tufts research scientists work with federal agencies to establish the USDA Dietary Guidelines, the Dietary Reference Intakes, and other significant public policies.
Andrea Grossman | Newswise Science News
NIH scientists describe potential antibody treatment for multidrug-resistant K. pneumoniae
14.03.2018 | NIH/National Institute of Allergy and Infectious Diseases
Researchers identify key step in viral replication
13.03.2018 | University of Pittsburgh Schools of the Health Sciences
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.
In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
19.03.2018 | Event News
16.03.2018 | Event News
13.03.2018 | Event News
21.03.2018 | Physics and Astronomy
21.03.2018 | Materials Sciences
21.03.2018 | Life Sciences