Assessment of Aflatoxins and Heavy Metals in Zingiber officinale (Ginger) Across the Value Chain in Kaduna and Oyo States, Nigeria and the Use of Probiotics for Aflatoxin Detoxification

Summary

Fifty-one ginger samples were collected from major production areas in Kaduna State (Jaba, Kachia, Zango local government areas) and from the market in Oyo State (Ibadan), representing production, processing, storage, milling, and market stages of the value chain. The study measured aflatoxins (B1, B2, G1, G2) and heavy metals (mercury, cadmium, lead, copper, zinc, chromium). The mercury finding was the most toxicologically relevant: the estimated probable daily intake of mercury from Kaduna samples was 0.572 mg/kg body weight per day, exceeding the JECFA tolerable limit of 0.23 mg/kg body weight per day. Lead was detectable in Oyo State samples (estimated limit 0.007 mg/kg body weight per day) but not detected in Kaduna samples. Probiotic strains (Lactiplantibacillus plantarum ATCC 8014 and Lactobacillus helveticus ATCC 15009) reduced aflatoxin concentrations by approximately 50% at 120 hours.

Key numbers

Measure	Value	Units	Matrix	Source location
Estimated probable daily intake, mercury (Kaduna)	0.572	mg/kg body weight per day	Ginger (all forms)	Abstract, p. 1
JECFA tolerable limit, mercury	0.23	mg/kg body weight per day	Reference value	Abstract
Estimated probable daily intake, lead (Oyo)	0.007	mg/kg body weight per day	Ginger (all forms)	Abstract, p. 1
Lead in Kaduna samples	not detected	mg/kg	Ginger	Abstract
Probiotic aflatoxin reduction	~50%	percentage	Spiked ginger (50 ng/g)	Abstract

Methods (brief)

Samples collected along the value chain at production, processing (drying, milling), storage, and market stages. Forms included fresh, split-dried, and milled ginger. Metal analysis performed by ICP-MS (mercury speciation not separately reported; total mercury reported). Aflatoxins analyzed by competitive ELISA. Probiotic trials conducted in vitro at 120 hours incubation with L. plantarum ATCC 8014 and L. helveticus ATCC 15009. No CRM recovery values reported in the available pages.

Evidence fitness

The mercury EDI from Kaduna ginger substantially exceeded the tolerable limit, raising a food safety signal for a commodity that Nigeria exports globally at high volume. The study is limited by the small number of samples and by the absence of reported CRM recoveries. The lead non-detection in Kaduna and low detection in Oyo samples suggests the mercury finding, not lead, is the primary metal concern in this matrix for this region. The probiotic aflatoxin data are relevant to the food safety dimension but do not affect metal exposure estimates.

Limitations

Sample sizes per stage not fully reported. CRM recovery data not stated in abstract or introduction. The EDI calculation basis (fresh weight vs. dry weight) requires verification against the full methods section. The mercury exceedance is from a single state and cannot be generalized to all Nigerian ginger supplies.

Dietary heavy-metal exposure
Spices
metals/total-mercury
Lead

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Institute of Contaminant Standards. (2026). Assessment of Aflatoxins and Heavy Metals in Zingiber officinale (Ginger) Across the Value Chain in Kaduna and Oyo States, Nigeria and the Use of Probiotics for Aflatoxin Detoxification. Heavy Metal Index. https://heavymetalindex.com/sources/falade2026-nigeria-ginger-aflatoxins-heavy-metals

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