Abstract
Objectives
Zinc (Zn) deficiency is affecting 17% of the world's population. Although whole blood, plasma, and urine Zn decrease in severe Zn deficiency, accurate assessment of Zn status is difficult. Hence, as suggested by the World Health Organization, sensitive and specific biomarkers of Zn status are needed. Previously, we suggested the concept of the essential role of Zn for ∆6-desaturase activity. For the first time, we tested and implemented a previously unexplored biomarker of Zn status related to erythrocyte ∆6-desaturation, the LA: DGLA (linoleic acid: dihomo-γ-linolenic acid) ratio. We evaluated the sensitivity of the erythrocyte LA: DGLA ratio to changes in supplemental Zn intake. A significant negative correlation was found between dietary Zn deficiency and the LA: DGLA ratio. Our objective is to provide further and recent evidence to demonstrate that the LA: DGLA ratio is a useful and effective biomarker to assess Zn status.
Methods
The efficacy of the LA: DGLA ratio to predict the Zn status of subjects consuming a wheat-based diet, a representative diet of the target Zn-deficient populations, was evaluated in vivo (Gallus gallus). Two groups of birds (n = 15) were fed two different diets, a “high-Zn” diet (46.5 ppm Zn) and a “low-Zn” diet (32.8 ppm Zn), for 6 weeks. Dietary Zn intake, body weight, serum zinc, and the erythrocyte fatty acid profile were assessed.
Results
Serum and tissues (feather and nail) Zn concentrations were greater in the high-Zn group (P < 0.05). Duodenal expression of Zn transporters demonstrated a higher mean value in the tissues collected from the birds fed a low-Zn diet (n = 15, P < 0.05). Hepatic ∆6-desaturase expression showed a higher mean value in birds fed high-Zn diets (P < 0.05). LA: DGLA ratio was higher (P < 0.05) in the low-Zn group of birds at all-time points. Even though both groups of birds were fed Zn-deficient diets, with only 14 ppm differential in dietary Zn content, still the LA: DGLA ratio differentiated clearly between the groups, which demonstrates the sensitivity of the biomarker to change in accordance with dietary Zn intake.
Conclusions
Recent evidence demonstrate the potential of the LA: DGLA ratio to be used as an additional biomarker of Zn status in humans. To date, research shows that the LA: DGLA ratio corresponds to dietary Zn manipulations, both in animals and humans.
Funding Sources
USDA-ARS.
Supporting Tables, Images and/or Graphs
Dietary Zinc Deficiency Affects Blood Linoleic Acid: Dihomo-γ-linolenic Acid (LA:DGLA) Ratio; a Sensitive Physiological Marker of Zinc Status in Vivo (Gallus gallus)
