FADS1 and FADS2 as biomarkers of Zn status – a systematic review and meta-analysis

Figures & data

Table 1. Summary of characteristics and findings of RTCs and Zn-controlled feeding trials.

Reference	Study design / Country	Study population	Type and content of Zn intervention	Control arm	Duration	D5D outcomes	D6D outcomes	Estimation of desaturases
Lowe et al. 2021	RCT (cross-over design) / Pakistan	Women of reproductive age from 50 households, n = 25 randomized to bio-fortified wheat and n = 25 randomized to control flour	Zinc bio-fortified wheat (Zincol-2016) − 49.3 ± 5.6 mg/kg)	Control flour (Galaxy) − 22.2 ± 2.9 mg.kg	2-week baseline period with the control flour, 8-week intervention period -received the bio-fortified flour or the control flour	Group A - no significant difference in FADS1 activity index. Group B – marginally significant increase after 8 weeks of intervention (p = 0.059).	Group A – no significant difference in FADS2 activity. Group B – significant decrease after 8 weeks of intervention.	FADS1 = ARA/DGLA FADS2 = GLA/LA
Jongstra et al. 2022	RCT / Bangladesh	520, 12-36 months old children, zinc bio-fortified group n = 259, control group n = 261	Zinc bio-fortified rice in cooked portions to their households daily (28.5 ± 3.5 μg/g of Zn in raw rice)	Control rice in cooked portions to their households daily (14.7 ± 0.8 of Zn in raw rice)	9 months	No significant effect of treatment on D5D activity. The time-by-treatment interaction was not significant.	No significant effect of treatment on D6D activity. The time-by-treatment interaction was not significant either.	D5D = AA/DGLA D6D = GLA/LA
Liong et al. 2021	Controlled feeding trial / USA	36 healthy adult men, aged 18 to 51 years	Bread made from zinc-biofortified wheat (10.9 mg zinc/d) with no additional phytate (0.6 g/d total phytate) for 6 weeks and 25-mg zinc supplement for 2 weeks	Placebo capsules for 2 weeks during the last phase of trial that involved Zn supplementation	10 weeks (2 weeks of run-in period, followed by 6 weeks of bread consumption and 2 weeks of supplementation/placebo together with the bread consumption)	FADS1 activity significantly decreased during the MP2 period, when the participants consumed 10.9 mg Zn/d (of which 6.3 mg was provided through bread without additional phytate). No changes in FADS1 activity during MP3 when 25 mg/d of supplemental Zn was given to half of the men.	FADS2 activity significantly increased during MP2 period. No change in FADS2 activity during MP3 when the 25 mg/d of supplemental zinc was given to half of the men.	FADS1 = AA/DGLA FADS2 = GLA/LA
Massih et al. 2021	RCT / USA	35 healthy men, mean age 24.7 ± 1.36 years	25 mg zinc as zinc gluconate in the fasted state 30 min before breakfast [zinc before breakfast (ZBB)]	25 mg zinc as zinc gluconate consumed with breakfast [zinc with breakfast (ZWB)]	13 days	Consumption of zinc supplement with breakfast led to a significantly different FADS1 activity index compared to consumption of supplement without food (p = 0.044).	When controlling for baseline values, FADS2 activity index with supplementation did not differ between the groups (p = 0.21).	FADS1 = ARA/DGLA FADS2 = GLA/LA
Suh et al. 2022	Before/after feeding trial / USA	Eighteen healthy men aged 19–45 y with a BMI (in kg/m2) between 18 and 30	Bio-fortified rice − 6 mg Zn/d (and 1.5 g phytate); 10-mg Zn/d diet without phytate; ad libitum diet supplemented with 25 mg Zn/d.	None	6 mg Zn/d for 2 wk (MP1) followed by a 10-mg Zn/d diet for 4 wk (MP2), and ad libitum diet supplemented with 25 mg Zn/d was then fed for 3 wk (MP3).	FADS1 activity increased significantly, by 28.9% (p = 0.007) and 45.6% (p = 0.00005) following MP1 and MP2 phases; the activity levels returned to baseline following the 25-mg Zn/d supplementation period.	FADS2 activity trended higher by 56% (p = 0.07) at the end of MP1, and it was increased by 126% (p = 0.0001) following MP2. Supplementation with 25 mg Zn/d in MP3 decreased the FADS2 activity back to baseline concentrations.	FADS1 = AA/DGLA FADS2 = LA/GLA
Hernández et al. 2020	RCT / Chile	Sixty patients with T2D; mean age in the zinc group (n = 30) 54.9 ± 6.4; in placebo group (n = 30) 55.0 ± 7.6	30 mg of elemental zinc (as sulfate)	Placebo capsules (magnesium silicate)	24 months	There was no treatment effect for the D5D activity.	D6D activity was unaffected by Zn supplementation.	D5D n-6: AA/DGLA D6D n-6: GLA/LA
Chimhashu et al. 2018	RCT / Benin, West Africa	186 healthy children, 84 were girls; mean age in the intervention arm (n = 89): 8.10 (6.64, 9.59), in the control arm (n = 97): 8.5 (7.33, 9.58).	Water filtered with a Zn fortification chamber. Average daily zinc intake was 4·3 (IQR 3·5, 5·2) mg and 2·8 (IQR 0·0, 4·5) mg on school days and over the entire study	Water filtered with a placebo chamber	20 weeks	Correlation with Zn status: r=-0.170, p = 0.036. There was a statistically significant difference in the change of D5D activity from baseline in the placebo group (in the whole study sample, not in Zn-deficient children).	Correlation with plasma Zn: r 0.293, P ≤ 0.0001. No significant difference in the DGLA:LA ratio in the Zn-deficient group when compared with the Zn-sufficient group (0.15 (SD 0.43) and 0.14 (SD 0.42), respectively, P = 0.217)	D5D = AA/DGLA D6D = DGLA/LA

Table 2. Summary of characteristics and findings of cross-sectional studies.

Reference	Study design/Country	Study population	D5D outcomes	D6D outcomes	LA:DGLA	Estimation of desaturases
Monteiro et al. 2021	Cross-sectional study / USA	1614 participants (771 females and 843 males) from NHANES 2011–2012 database, mean age of women: 48.6 ± 17.5; of men: 47.6 ± 17.7 years	NR	NR	Correlation with Zn status (women): r = − 0.05, p = 0.39; (men): r = − 0.11, p = 0.07. Correlations with Zn intake adjusted for energy intake in women: r=-0.05, p = 0.12, in men: r = 0.03, p = 0.32).	NA
Takic et al. 2021	Cross-sectional study / Serbia	40 adult patients undergoing hemodialysis treatment (9 women), mean age: 56 ± 15 years	Correlation with serum zinc status: r=-0.168, p = 0.296. Correlations with dietary Zn: r=-0.092, p = 0.564.	Correlations with serum zinc concentration: r = 0.311, p = 0.037. Correlations with dietary Zn: r = 0.011, p = 0.947.	Correlation with serum zinc status: r = −0.335, p = 0.033. Correlations with dietary Zn: r=-0.025, p = 0.883.	D5D: AA/DGLA D6D: DGLA/LA
Knez et al. 2018	Cross-sectional study / Serbia	27 dyslipidemic adults, median age 57.00 [16.00]	Correlations with Zn status: r = 0.168 p = 0.471.	Correlations with Zn status: r = 0.168 p = 0.443.	Correlations with Zn status: r = −0.132 p = 0.058. Correlation with Zn intake: r = −0.38, p = 0.05.	D5D: AA/DGLA D6D: GLA/AA
Knez et al. 2016	Cross-sectional study / Serbia	54 healthy volunteers, mean age: 40.4 ± 7 years	NR	NR	Correlation with Zn status: r= −0.35, p = 0.01. Correlation with Zn intake: r=-0.01, p = 0.94.	NA
Yary et al. 2017	Cross-sectional study / Eastern Finland	2189 men from the prospective Kuopio Ischemic Heart Disease Risk Factor Study, aged 42–60 y and free of T2D at baseline in 1984–1989	D5D activity was the highest in the 1st Zn status quartile, and lowest in the 4th.	D6D activity was the lowest in the first Zn status quartile and the highest in the 4th.	NR	D5D: AA/DGLA D6D: GLA/LA
Wang et al. 2008	Cross-sectional study / China	232 community-dwelling subjects aged between 35 and 60 years; mean age essential hypertension patients (n = 109): 44.3 ± 7.5; non-hypertensive patients (n = 123): 42.8 ± 4.4	NR	Correlation with Zn status: r= −0.13, p > 0.05.	NR	D6D: AA/LA

Table 3. Summary of characteristics and findings of animal model studies.

Reference	Study design / Country	Study animals	Description of study groups	Zn content	Study duration	Sample	D5D outcomes	D6D outcomes	Desaturase Estimation
Stawarska et al. 2021	Controlled study / Poland	24 Spraque-Dawley female rats with breast cancer	3 groups, 8 rats in each group: control, and 2 groups received either Zn microparticles (342 nm) or Zn nanoparticles (99 nm).	Both micro- and nanoparticles of zinc were administered via gavage in the dose of 4.6 mg/mL in 0.4 mL of water.	20 weeks	Serum	The highest activity was observed in the control group, it was slightly lower in the group that received nanoparticles, and considerably lower in the group receiving Zn in microparticles.	The highest activity was observed in the control group, it was slightly lower in the group that received nanoparticles, and considerably lower in the group that received Zn in microparticles.	D5D: AA/DGLA D6D: GLA/LA
Knez et al. 2018	Controlled study / USA	30 Cornish cross fertile broiler eggs Gallus gallus	High Zn diet n = 15, low Zn diet n = 15.	High Zn diet: 46.5 µg Zn/g; low Zn diet: 32.8 µg Zn/g	42 days	Erythrocytes	NA	There were statistically significant differences in the LA: DGLA ratio among the groups, with the higher ratio measured in the group of birds fed the low Zn diet, at all-timepoints (p < 0.05).	D6D: LA/DGLA
Reed et al. 2014	Controlled study / USA	48 Cornish cross-fertile broiler eggs Gallus gallus	2 equal groups: Zinc adequate control diet (n = 12) and Zinc deficient diet (n = 12).	Zinc adequate control diet: 42.29 μg/g zinc); Zinc deficient diet: 2.55 μg/g zinc)	28 days	Erythrocytes	NA	The % w/w ratio was significantly elevated in the Zn-deficient group on days 7, 14, and 21 but not significantly different on day 28. Overall, the Zn-deficient group had a higher cumulative mean ratio (p < 0.001).	D6D: LA/DGLA
Eder and Kirchgessner 1995	Controlled study / Germany	36 male Sprague-Dawley rats weighing 121 + 4 g	4 groups, 9 rats each: Zn adequate/coconut oil; Zn deficient/coconut oil; Zn adequate/linseed oil; Zn deficient/linseed oil.	The Zn deficient diet contained 0.5 mg Zn/kg. The zinc adequate diet was supplemented with 30 mg/kg Zn (as zinc sulfate-heptahydrate).	10 days (the trial had to stop as Zn def rats became severely ill)	Hepatic microsomes	Activity of D5D-desaturase was not influenced by zinc deficiency in the rats fed both types of dietary oil.	D6D-desaturase activity using linoleic acid as substrate was not different between Zn-deficient and Zn-adequate rats fed coconut oil diet but was higher in Zn-deficient rats fed linseed oil diet than in Zn-adequate rats fed linseed oil diet.	D5D: the amount of (1-14 C)-arachidonic acid produced from dihomo-7-(1-14C)-linolenic acid. D6D: the amount of (1-14 C)-linolenic acid resp. (1-14 C) octadecatetraenoic acid produced from (1-14 C)-linoleic acid resp. α-(1-14 C)-linolenic acid.
Kudo, Nakagawa, and Waku 1990	Controlled study / Japan	Three-week-old male Wistar rats weighing 50-60 g	3 groups (10-12 rats each): ad libitum-fed rats were allowed free access to a zinc-adequate (AL) or zinc-deficient (ZD) diet. The food restricted pair-fed (PF) rats were given the zinc-adequate diet	A zinc-adequate diet was prepared by adding zinc as Zn (CH3COO)2 ∼ 2H20 to the basal diet to 50 ppm Zn. Zn deficient - <2 ppm	2 weeks	Total phospholipids in liver	NA	The values for D6D were higher in the group receiving Zn deficient diet ad libitum, compared to the group receiving Zn adequate diet ad libitum. The highest values were observed in rats receiving zinc-adequate diets.	D6D: AA:LA
Cunnane and Krieger 1988	Controlled study / Canada	30 weanling male Sprague-Dawley rats (mean weight 50 (SE 2) g)	3 groups, 10 rats in each group: Zn-deficient, control and High-Zn group.	The Zn-deficient diet contained 3-4 mg Zn/kg, the control diet 36 mg Zn/kg and the High-Zn diet 411 mg Zn/kg.	10 weeks	Plasma and liver	NR	In the phosphatidylcholine subclass the ratio of LA/AA was higher in the Zn-deficient group compared to the controls (P < 0.01); in the phosphatidylserine subclass the ratio was lower in the Zn-high group compared with the controls (P < 0.01). In the phospholipid subclass of the liver, the ratio was higher in the Zn-deficient group than in the controls or High-Zn group.	D6D: LA/AA
Ayala and Brenner 1983	Controlled study / Argentina	12 Male weanling Wistar rats	Rats were divided into groups of 4 rats each and received either a Zn sufficient or Zn deficient diet.	55 ppm of Zn, and a Zn deficient diet (1.2 ppm)	60 days. After 18 days, the Zn deficient rats got ill, and were switched to the other diet until the end of 60 days.	Liver and testes tissues	Significantly higher values were presented in Zn adequate livers (p < 0.001) and testes (p < 0.01).	Higher values were presented in Zn adequate livers and testes (both p < 0.001).	D5D: DGLA/AA D6D: LA/GLA
Clejan et al. 1982	Controlled study / USA	38 male Sprague-Dawley rats, weighing 90 + 20 g	They were divided into 6 groups, out of which the 1st two were of interest: 1st group: Zn supplemented diet (n = 8), 2nd group: Zn deficient diet (n = 8).	1st group = purified Zn-supplemented diet containing 100 mg/kg Zn as Zn chloride. 2nd group = Zn-deficient diet (1.2 ppm Zn).	6 weeks	Liver microsomes	Higher activity was measured in the Zn supplemented groups vs the Zn deficient group.	Higher activity was measured in Zn supplemented group	Desaturation reaction assays

Figure 1. PRISMA Flowchart.

Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021;372:n71. doi: 10.1136/bmj.n71.

For more information, visit:http://www.prisma-statement.org/.

Figure 2. Meta analysis data.

Figure 3. Meta analysis data.

Figure 4. Meta analysis data

Figure 5. Meta analysis data

Figure 6. Meta analysis data

Figure 7. Meta analysis data

Figure 8. Meta analysis data.

Figure 9. Meta analysis data.

Lowe, N. M., M. Zaman, M. J. Khan, A. K. M. Brazier, B. Shahzad, U. Ullah, G. Khobana, H. Ohly, M. R. Broadley, M. H. Zia, et al. 2021. Biofortified wheat increases dietary zinc intake: a randomized controlled efficacy study of zincol-2016 in rural Pakistan. Frontiers in Nutrition 8:809783. doi: 10.3389/fnut.2021.809783.

 PubMedGoogle Scholar

Jongstra, R., M. M. Hossain, V. Galetti, A. G. Hall, R. R. Holt, C. I. Cercamondi, S. F. Rashid, M. B. Zimmermann, M. K. Mridha, and R. Wegmueller. 2022. The effect of zinc-biofortified rice on zinc status of Bangladeshi pre-school children: a randomized, double-masked, household-based controlled trial. The American Journal of Clinical Nutrition 115 (3):724–37. doi: 10.1093/ajcn/nqab379.

 PubMed Web of Science ®Google Scholar

Liong, E. M., C. M. McDonald, J. Suh, J. L. Westcott, C. P. Wong, C. Signorell, and J. C. King. 2021. Zinc-biofortified wheat intake and zinc status biomarkers in men: randomized controlled trial. The Journal of Nutrition 151 (7):1817–23. doi: 10.1093/jn/nxab092.

 PubMed Web of Science ®Google Scholar

Massih, Y. N., A. G. Hall, J. Suh, and J. C. King. 2021. Zinc supplements taken with food increase essential fatty acid desaturation indices in adult men compared with zinc taken in the fasted state. The Journal of Nutrition 151 (9):2583–9. doi: 10.1093/jn/nxab149.

 PubMed Web of Science ®Google Scholar

Suh, J. H., S. J. Zyba, M. Shigenaga, C. M. McDonald, and J. C. King. 2022. Marginal zinc deficiency alters essential fatty acid metabolism in healthy men. The Journal of Nutrition 152 (3):671–9. doi: 10.1093/jn/nxab425.

 PubMed Web of Science ®Google Scholar

Hernández, M. C., P. Rojas, F. Carrasco, K. Basfi-Fer, R. Valenzuela, J. Codoceo, J. Inostroza, and M. Ruz. 2020. Fatty acid desaturation in red blood cell membranes of patients with type 2 diabetes is improved by zinc supplementation. Journal of Trace Elements in Medicine and Biology : Organ of the Society for Minerals and Trace Elements (GMS) 62:126571. doi: 10.1016/j.jtemb.2020.126571.

 PubMed Web of Science ®Google Scholar

Chimhashu, T., L. Malan, J. Baumgartner, P. J. van Jaarsveld, V. Galetti, D. Moretti, C. M. Smuts, and M. B. Zimmermann. 2018. Sensitivity of fatty acid desaturation and elongation to plasma zinc concentration: a randomised controlled trial in Beninese children. British Journal of Nutrition 119 (6):610–9. doi: 10.1017/S000711451700366X.

 PubMed Web of Science ®Google Scholar

Monteiro, J. P., C. A. Fuzo, F. V. Ued, and J. Kaput. 2021. Dietary patterns related to zinc and polyunsaturated fatty acids intake are associated with serum linoleic/dihomo-γ-linolenic ratio in NHANES males and females. Scientific Reports 11 (1):12215. doi: 10.1038/s41598-021-91611-7.

 PubMed Web of Science ®Google Scholar

Takic, M., M. Zekovic, B. Terzic, A. Stojsavljevic, M. Mijuskovic, S. Radjen, and D. Ristic-Medic. 2021. Zinc deficiency, plasma fatty acid profile and desaturase activities in hemodialysis patients: is supplementation necessary? Frontiers in Nutrition 8:700450. doi: 10.3389/fnut.2021.700450.

 PubMed Web of Science ®Google Scholar

Knez, M., E. Tako, R. P. Glahn, N. Kolba, E. de Courcy-Ireland, and J. C. R. Stangoulis. 2018. Linoleic acid: dihomo-γ-linolenic acid ratio predicts the efficacy of Zn-biofortified wheat in chicken (Gallus gallus). Journal of Agricultural and Food Chemistry 66 (6):1394–400. doi: 10.1021/acs.jafc.7b04905.

 PubMed Web of Science ®Google Scholar

Knez, M., J. C. R. Stangoulis, M. Zec, J. Debeljak-Martacic, Z. Pavlovic, M. Gurinovic, and M. Glibetic. 2016. An initial evaluation of newly proposed biomarker of zinc status in humans - linoleic acid: dihomo-γ-linolenic acid (LA:DGLA) ratio. Clinical Nutrition ESPEN 15:85–92. doi: 10.1016/j.clnesp.2016.06.013.

 PubMed Web of Science ®Google Scholar

Yary, T., S. Voutilainen, T. P. Tuomainen, A. Ruusunen, T. Nurmi, and J. K. Virtanen. 2017. Omega-6 polyunsaturated fatty acids, serum zinc, delta-5- and delta-6-desaturase activities and incident metabolic syndrome. Journal of Human Nutrition and Dietetics 30 (4):506–14. doi: 10.1111/jhn.12437.

 PubMed Web of Science ®Google Scholar

Wang, S., A. Ma, S. Song, Q. Quan, X. Zhao, and X. Zheng. 2008. Fasting serum free fatty acid composition, waist/hip ratio and insulin activity in essential hypertensive patients. Hypertension Research 31 (4):623–32. doi: 10.1291/hypres.31.623.

 PubMed Web of Science ®Google Scholar

Stawarska, A., M. Czerwonka, R. Wyrębiak, R. Wrzesień, and B. Bobrowska-Korczak. 2021. Zinc affects cholesterol oxidation products and fatty acids composition in rats’ serum. Nutrients 13 (5):1563. doi: 10.3390/nu13051563.

 PubMed Web of Science ®Google Scholar

Reed, S., X. Qin, R. Ran-Ressler, J. T. Brenna, R. P. Glahn, and E. Tako. 2014. 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). Nutrients 6 (3):1164–80. doi: 10.3390/nu6031164.

 PubMed Web of Science ®Google Scholar

Eder, K, and M. Kirchgessner. 1995. Zinc deficiency and activities of lipogenic and glycolytic enzymes in liver of rats fed coconut oil or linseed oil. Lipids 30 (1):63–9. doi: 10.1007/BF02537043.

 PubMed Web of Science ®Google Scholar

Kudo, N., Y. Nakagawa, and K. Waku. 1990. Effects of zinc deficiency on the fatty acid composition and metabolism in rats fed a fat-free diet. Biological Trace Element Research 24 (1):49–60. doi: 10.1007/BF02789140.

 PubMed Web of Science ®Google Scholar

Cunnane, S. C, and I. Krieger. 1988. Long chain fatty acids in serum phospholipids in acrodermatitis enteropathica before and after zinc treatment: a case report. Journal of the American College of Nutrition 7 (3):249–50. doi: 10.1080/07315724.1988.10720242.

 PubMed Web of Science ®Google Scholar

Ayala, S, and R. R. Brenner. 1983. Essential fatty acid status in zinc deficiency. Effect on lipid and fatty acid composition, desaturation activity and structure of microsomal membranes of rat liver and testes. Acta Physiologica Latino Americana 33 (3):193–204.

 PubMedGoogle Scholar

Clejan, S., M. Castro‐Magana, P. J. Collipp, E. Jonas, and V. T. Maddaiah. 1982. Effects of zinc deficiency and castration on fatty acid composition and desaturation in rats. Lipids 17 (3):129–35. doi: 10.1007/BF02535092.

 PubMed Web of Science ®Google Scholar