Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Trends of Vitamin B6 Status in US Population Sample

21.05.2008
In an epidemiological study, Tufts University researchers identified trends of vitamin B6 status in a sample of the United States population based on measures of plasma pyridoxal 5¡¯- phosphate (PLP) levels in the bloodstream.

Plasma PLP is the indicator used by the federal government to set the current Recommended Dietary Allowance (RDA) of vitamin B6, a nutrient essential for red blood cell function and important for maintaining a healthy immune system and blood glucose levels.

¡°Across the study population, we noticed participants with inadequate vitamin B6 status even though they reported consuming more than the Recommended Daily Allowance of vitamin B6, which is less than 2 milligrams per day,¡± says Martha Savaria Morris, PhD, an epidemiologist at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. ¡°We also identified four subgroups where this trend seemed most prominent: women of reproductive age, especially current and former users of oral contraceptives, male smokers, non-Hispanic African-American men, and men and women over age 65.¡± Someone with inadequate vitamin B6 status is at risk of becoming Vitamin B6 deficient should their vitamin B6 levels drop too low.

Corresponding author Morris and colleagues studied 7,822 blood samples of men and women ages one-year and older collected from the 2003-2004 National Health and Nutrition Examination Survey (NHANES). Vitamin B6 inadequacy was defined as a plasma PLP concentration less than 20 nmol/L. To the authors¡¯ knowledge, the current study is the first large scale study to use plasma PLP concentrations to evaluate vitamin B6 status in free-living people of all ages. The investigators were also able to consider whether the current RDA guaranteed adequate vitamin B6 status because study participants were questioned about supplement use and two days¡¯ worth of food intake.

Eleven percent of supplement users and nearly a quarter of non-users demonstrated plasma PLP blood levels of less than 20 nmol/L. Within the four sub-groups where vitamin B6 inadequacy was most prominent, the prevalence of low plasma PLP levels significantly exceeded 10 percent©¤ even among those who consumed 2 to 2.9 milligrams per day of vitamin B6. The RDAs for vitamin B6 in men and women who are not pregnant or lactating are as follows: 1.3 mg per day for men and women ages 19-50, 1.7 mg per day for men over age 50 and 1.5 mg for women over age 50.

Writing in the May 2008 issue of the American Journal of Clinical Nutrition, Morris and colleagues noted a stark contrast in plasma PLP levels between women of childbearing age (ages 13 to 54) and their male peers. ¡°When we looked specifically at the plasma PLP levels in women of childbearing age, we noticed they were significantly lower than in males in approximately the same age group.¡± Morris continues, ¡°Most importantly, the data suggest that oral contraceptive users have extremely low plasma PLP levels. Three quarters of the women who reported using oral contraceptives ©¤but not vitamin B6 supplements ©¤were vitamin B6 deficient.¡±

A pattern of low vitamin B6 status also surfaced in menstruating women who reported using oral contraceptives but who were no longer using them at the time of the NHANES survey. Among women in this sub-group who were not taking vitamin B6 supplements, 40 percent demonstrated plasma PLP blood levels below the cut-off for vitamin B6 inadequacy. Morris says, that although these results are somewhat surprising, the link between oral contraceptive use and vitamin B6 deficiency remains unclear. ¡°The vitamin could be stored elsewhere in the bodies of the oral contraceptive users, or in a different form, since our study only examined plasma PLP.¡±

To further support their findings, Morris and colleagues measured homocysteine levels in the blood and compared them against the plasma PLP measures. Homocysteine is an amino acid that can accumulate in the blood if vitamin B6 levels are too low. Though study participants using oral contraceptives at the time of the survey did not demonstrate elevated homocysteine levels, the homocysteine concentrations of former users were significantly higher than those of women who had never used oral contraceptives. Morris says this could mean that oral contraceptive use has an effect on vitamin B6 status that is masked during use by acute effects of the exposure.

Because the study shows association and not causation, Morris stresses that further research is necessary to determine whether the RDA for vitamin B6 is high enough. ¡°We have identified populations with a high prevalence of apparently inadequate vitamin B status,¡± Morris says. ¡°However, it is important to recognize that signs of deficiency are not seen at plasma PLP concentrations of 20 nmol/L and that dietary assessment is imperfect.¡±

According to the National Institutes of Health (NIH), vitamin B6 deficiency is rare in the United States, but it can cause a form of anemia similar to iron deficiency anemia. Vitamin B6 is widely distributed in the American diet, and baked potatoes, bananas, 100 percent fortified cereals and chicken are particularly good sources. Morris says, ¡°The question our study raises is whether, due to aging, genetics, or exposures, some population subgroups need supplements to achieve the current biochemical definition of adequate status.¡±

This study was supported by the National Institutes of Health and by the U.S. Department of Agriculture.

Morris MS, Picciano, MF, Jacques PF, Selhub, J. American Journal of Clinical Nutrition. 2008 (May); 87: 1446 ¨C54.

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
Further information:
http://www.tufts.edu

More articles from Health and Medicine:

nachricht Investigators may unlock mystery of how staph cells dodge the body's immune system
22.09.2017 | Cedars-Sinai Medical Center

nachricht Monitoring the heart's mitochondria to predict cardiac arrest?
21.09.2017 | Boston Children's Hospital

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>