Dietary zinc deficiency affects blood linoleic acid: dihomo-gamma-linolenic acid (LA:DGLA) ratio; a reactive physiological marker of zinc status in vivo (Gallus gallus)

Authors: REED, SPENSER - Cornell University; XIA, QIN - Cornell University; RINAT, RAN-RESSLER - Cornell University; THOMAS, BRENNA - Cornell University; Glahn, Raymond; Tako, Elad

Submitted to: Nutrients
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/2014
Publication Date: 3/20/2014
Citation: Reed, S., Xia, Q., Rinat, R., Thomas, B., Glahn, R.P., Tako, E. 2014. Dietary zinc deficiency affects blood linoleic acid: dihomo-gamma-linolenic acid (LA:DGLA) ratio; a reactive physiological marker of zinc status in vivo (Gallus gallus). Nutrients. 6:1164-1180. DOI: 10.3390/nu6031164.

Interpretive Summary: Zinc (Zn) is a vital micronutrient for the activity of over 300 enzymes in the body. To date, accurate biological markers of Zn status are still needed. The aim of this study was to evaluate the broiler chicken as an animal model to test dietary Zn deficiency as well as assess the sensitivity of a previously unexplored potential Zn biomarker. Diets identical in composition (except Zn concentration) were formulated and two groups of birds were randomly separated upon hatching into two diets, Zn(+) (42 ug/g zinc) and Zn(-) (2.5 ug/g zinc). Dietary Zn consumption, body weight, and serum Zn were measured weekly. Additional blood was taken each week for red blood cells fatty acid analysis. At the end of the study, tissues were collected for gene expression analysis. As expected, body weight, feed consumption, Zn intake, and serum Zn were significantly higher in the Zn(+) versus Zn(-) group. Liver TNF-a, IL-1B, and IL-6 (tissue functional factors) gene expression were higher in the Zn(+) group. Liver delta-6 desaturase (Zn dependent enzyme) was significantly higher in the Zn(+) group. LA:DGLA ratio (indicator for Zn status) was significantly elevated in the Zn(-) group compared to the Zn(+) group (22.61+/-0.57 and 18.5+/-0.53, % w/w, respectively). This study suggests red blood cells LA:DGLA ratio is able to differentiate zinc status between subjects with varying levels of zinc deficiency, and may be a novel biomarker to assess dietary zinc manipulation. Further studies are warranted to assess LA:DGLA ratio implementation in Zn deficiency.

Technical Abstract: Dietary Zinc (Zn) deficiency affects approximately 30% of the world’s population. Zinc is a vital micronutrient and is important for the body’s ability to function. To date, accurate biological markers of the Zn subject’s status are still needed. The aim of this study was to evaluate the chicken model as an animal model to test dietary Zn deficiency as well as assess the sensitivity of a previously unexplored potential Zn biomarker, by calculating the ratio of two long chain fatty acid [blood linoleic acid: dihomo-y-linolenic acid (LA:DGLA)]. The experimental diets were identical in composition (except Zn concentration and two groups of birds (n = 12) were randomly separated upon hatching into two diets, Zn(+) (42 ppm zinc) and Zn(-) (2.5 ppm zinc). Dietary Zn intake, body weight, and serum Zn were measured weekly (as Zn status assessment). Additional blood was taken each week for fatty acid analysis. At the conclusion of the study, tissues were collected for intestinal gene expression analysis (parameter for Zn status). As expected, body weight, feed consumption, Zn intake, and serum Zn were significantly higher in the Zn(+) versus Zn(-) group. Liver TNF-a, IL-1B, and IL-6 (Zn dependent factors) gene expression were higher in the Zn(+) group. Liver delta-6 desaturase (vital enzyme) was significantly higher in the Zn(+) group. LA:DGLA ratio was significantly elevated in the Zn(-) group compared to the Zn(+) group (22.61+/-0.570 and 18.5+\-0.530, % w/w, respectively, n =12, p < 0.001). This study suggests that blood LA:DGLA ratio is able to differentiate zinc status between subjects with varying levels of zinc deficiency, and may be a novel biomarker to assess dietary zinc manipulation. Further studies are warranted to assess LA:DGLA ratio implementation in Zn deficiency.