Multi-ethnic study suggests vitamin K may offer protective health
benefits in older age
Older adults with low vitamin K had higher death risk over 13 years
compared to those with adequate vitamin K levels

Date:
June 15, 2020
Source:
Tufts University, Health Sciences Campus
Summary:
A new, multi-ethnic study found adults aged 54-76 with low
circulating vitamin K levels were more likely to die within 13
years compared to those with adequate levels, suggesting vitamin
K may offer protective health benefits as we age.



FULL STORY ==========================================================================
A new, multi-ethnic study found older adults with low vitamin K levels
were more likely to die within 13 years compared to those whose vitamin
K levels were adequate. The results suggest vitamin K, a nutrient found
in leafy greens and vegetable oils, may have protective health benefits
as we age, according to the researchers.


==========================================================================
The meta-analysis, involving nearly 4,000 Americans aged 54-76, one-third
of whom were non-white, was led by researchers at the Jean Mayer USDA
Human Nutrition Research Center on Aging at Tufts University (USDA HNRCA)
and Tufts Medical Center and is published in The American Journal of
Clinical Nutrition.

The research team categorized participants according to their vitamin
K blood levels. They then compared risk of heart disease and risk of
death across the categories over approximately 13 years of follow-up.

The results showed no significant associations between vitamin K levels
and heart disease. However, the people with the lowest vitamin K levels
had a 19 percent higher risk of death, compared to the those with vitamin
K levels that reflected adequate vitamin K intake.

Vitamin K is a nutrient that is important for maintaining healthy blood vessels. It is found in leafy greens, such as lettuce, kale and spinach,
and in some vegetable oils, especially soybean and canola.

"The possibility that vitamin K is linked to heart disease and
mortality is based on our knowledge about proteins in vascular tissue
that require vitamin K to function. These proteins help prevent calcium
from building up in artery walls, and without enough vitamin K, they
are less functional," said first author Kyla Shea.



==========================================================================
Shea is a scientist on the HNRCA's vitamin K team, long renowned
for its work on the role of vitamin K in the prevention of chronic
disease. Sarah Booth, a co-author on the study and director of the USDA
HNRCA, developed the methodology for measuring vitamin K in blood. Her
research team measured the vitamin K levels in the study participants
and continues to generate data about vitamin K status in population and clinic-based studies.

"Similar to when a rubber band dries out and loses its elasticity, when
veins and arteries are calcified, blood pumps less efficiently, causing
a variety of complications. That is why measuring risk of death, in a
study such as this, may better capture the spectrum of events associated
with worsening vascular health," said last author Daniel Weiner, M.D., nephrologist at Tufts Medical Center, whose research includes vascular
disease in people with impaired kidney function.

While this study adds to existing evidence that vitamin K may
have protective health benefits, it cannot establish a causal
relationship between low vitamin K levels and risk of death because
it is observational. Additional studies are also needed to clarify
why circulating vitamin K was associated with risk for death but not
heart disease.

Methodology The study is a meta-analysis, which combined data from
participants in three ongoing studies: the Health, Aging, and Body
Composition Study, the Multi- Ethnic Study of Atherosclerosis, and
the Framingham Heart Study (Offspring Cohort). Vitamin K levels for participants in all three studies were measured after fasting, with the
same test, and processed at the same laboratory (the vitamin K laboratory
at the USDA HNRCA), minimizing the potential for laboratory-based
variation. The test showed levels of circulating phylloquinone, the
compound known as vitamin K1.

Participants on the blood thinner warfarin were excluded because vitamin
K counteracts the anti-clotting effects of warfarin. All participants were
free of heart disease at baseline and had vitamin K levels measured during
a single medical exam that was part of each study's regular protocol.

The statistical analysis adjusted for age, gender, race, ethnicity, BMI, triglycerides, cholesterol levels, smoking status, and use of medications
for diabetes or high blood pressure.

There are some limitations to the study, including that circulating phylloquinone was measured from a single blood draw, rather than from
repeated blood tests over time. Higher circulating phylloquinone may
reflect an overall healthier diet and lifestyle. Lastly, there were
fewer heart disease events compared to total deaths, which may have
limited researchers' ability to detect statistically significant risk
of heart disease.


========================================================================== Story Source: Materials provided by
Tufts_University,_Health_Sciences_Campus. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Daniel E Weiner, Stephen B Kritchevsky, Emelia J Benjamin,
Mary Cushman,
Gregory Matuszek, Sarah L Booth, Kathryn Barger, M Kyla
Shea. Vitamin K status, cardiovascular disease, and all-cause
mortality: a participant- level meta-analysis of 3 US cohorts. The
American Journal of Clinical Nutrition, 2020; 111 (6): 1170 DOI:
10.1093/ajcn/nqaa082 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200615115725.htm

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