Cornell team develops tool to better define zinc deficiency

Researchers at the university believe the method called the zinc status index (ZSI) can help determine zinc status, which is made even more difficult by the use of the mineral in the human body.

“The complexity and sophistication of zinc metabolism makes it very difficult to accurately measure zinc status,” says Elad Tako, associate professor of food science at the College of Agriculture and Life Sciences who helped develop the index.

“With global food insecurity and rising domestic obesity, malnutrition hits vulnerable, low-income populations. These problems are a big problem as they can lead to a zinc deficiency in the diet. “

In an article in Nutrients magazine, the team, which includes Jacquelyn Cheng, graduate student in food science, and Haim Bar, associate professor at the University of Connecticut, explain how the index uses a statistical model and is based on three pillars.

One of the pillars concerns the ratio of two fatty acids – linolenic acid to dihomo-gamma-linolenic acid (LA: DGLA ratio), which indicates the physiological status of the test person.

The second and third columns concern the gene expression of zinc-dependent proteins, which are influenced by the zinc status; and the gut microbiome as an additional tool to reflect the physiological status of zinc.

Dr. Tako had previously shown that a slight zinc deficiency can alter gene expression in the body and that a deficiency in zinc adversely affects the composition of the intestinal microbe population and thus the zinc metabolism.

Light and medium deficiency

“It is possible to detect severe zinc deficiency,” says Dr. Tako. “However, it is difficult to differentiate between mild and moderate cases of zinc deficiency.”

“So relying on just one biomarker can sometimes be a problem, which has led us to think about how we could develop an accurate zinc status index based on a panel of predictive biomarkers.”

In addition to the findings of Dr. Tako also incorporated five selected studies into the development of the ZSI. Here the studies found that the LA: DGLA ratio of the erythrocytes increased with lower food consumption of Zn,

In addition, the mRNA gene expression of Zn-related proteins in duodenal and liver tissue was altered and the intestinal microbiota populations differed.

There is currently no generally accepted individual measure for assessing the Zn status. Widely used biomarkers for Zn status are plasma, whole blood and urine Zn, which decrease in severe Zn deficiency.

The World Health Organization (WHO) estimates that a third of the world’s population is at risk of Zn deficiency based on the calculated proportion of people whose intake is below the country’s daily Zn requirement.

In order to detect a Zn deficiency in its early stages, the WHO has indicated that additional robust indicators for the Zn status need to be developed and already known clinical markers need to be further developed.

Emerging Zn status biomarkers that need further investigation include Zn-dependent proteins, Zn kinetics, flavor pungency, oxidative stress, and DNA integrity.

Assessment of dietary supplements

“The ZSI can be used to assess the effectiveness of nutritional interventions in target populations,” the team concludes.

“For example in connection with the evaluation of Zn bio-enriched staple foods, relevant food supplements or fortifications and other nutritional approaches that are used to improve the Zn status.

“Zn deficiency is often overlooked because of the subject’s inflammatory status (and when serum / plasma Zn levels are used as the physiological Zn status), which is particularly relevant in vulnerable populations,” they add.

“Therefore, the development and use of the ZSI is of great importance for the precise measurement of the physiological status of Zn. Further studies are required in order to further develop and refine the ZSI model.”

Source: nutrients

Published online:

“Zinc Status Index (ZSI) to quantify the physiological status of zinc.”

Authors: Jacquelyn Cheng et al.

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