“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
Researchers image atomic structure of important immune regulator
11.12.2018 | Brigham and Women's Hospital
Potential seen for tailoring treatment for acute myeloid leukemia
10.12.2018 | University of Washington Health Sciences/UW Medicine
What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.
Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...
Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.
Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...
New Project SNAPSTER: Novel luminescent materials by encapsulating phosphorescent metal clusters with organic liquid crystals
Nowadays energy conversion in lighting and optoelectronic devices requires the use of rare earth oxides.
Scientists have discovered the first synthetic material that becomes thicker - at the molecular level - as it is stretched.
Researchers led by Dr Devesh Mistry from the University of Leeds discovered a new non-porous material that has unique and inherent "auxetic" stretching...
Scientists from the Theory Department of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science (CFEL) in Hamburg have shown through theoretical calculations and computer simulations that the force between electrons and lattice distortions in an atomically thin two-dimensional superconductor can be controlled with virtual photons. This could aid the development of new superconductors for energy-saving devices and many other technical applications.
The vacuum is not empty. It may sound like magic to laypeople but it has occupied physicists since the birth of quantum mechanics.
10.12.2018 | Event News
06.12.2018 | Event News
03.12.2018 | Event News
11.12.2018 | Studies and Analyses
11.12.2018 | Health and Medicine
11.12.2018 | Physics and Astronomy