Lactobacillus Reduces Exposure to Aflatoxin-Contaminated Foods in Rural-Dwelling Children

by | Jun 16, 2020 | 2020, Digestive Health, Infant and Children's Health, Probiotics

Written by Angeline A. De Leon, Staff Writer. This study demonstrates the ability of the Lactobacillus species to effectively bind with aflatoxins in food, thus reducing their intestinal absorption.

fruits and vegetablesAflatoxins are toxic chemical compounds produced by fungi and represent one of the most common causes of food contamination 1,2. Their toxic effects have been linked to cancer and impaired developmental growth 3,4, making them a significant public health concern, particularly in developing countries. Among the major types of aflatoxins, the most common is aflatoxin B1, a classified carcinogen accounting for three-quarters of all aflatoxin-contaminated foods 1. In African countries, high levels of aflatoxins have been detected in cassava, corn, and ground nuts 5, with one study reporting that 72% of peanuts harvested from regions of Uganda were contaminated with aflatoxins 6, leading to the speculation that high rates of stunted growth among Ugandan children may be related to high aflatoxin exposure. Given that lactic acid bacteria are known for their ability to physically bind aflatoxin B1 7, current research looking at probiotic intake as one way to reduce aflatoxin absorption is under way 8. In a 2020 study 9 published in Microorganisms, dietary aflatoxin exposure was evaluated in a group of Ugandan children and the binding ability of Lactobacillus species to aflatoxin B1 tested.

An observational study was conducted in a sample of 10 children (aged 54-60 months) selected from a larger cohort of children living in southwestern Uganda, half of whom were considered stunted based on previous growth indices. Anthropometric measurements were taken, a food frequency questionnaire administered, and stool and urine samples collected. Concentration of aflatoxin B1 was measured in food samples (maize flour and peanuts), and aflatoxin M1 levels were tested in urine samples. A total of 23 Lactobacillus strains were isolated from fecal samples and analyzed using an aflatoxin B1 binding assay. A multivariate analysis was also carried out on the gut microbiota composition of the larger cohort of Ugandan children (n = 140) at the ages of 20-24 and 36 months.

All tested food ingredients were found to contain mean concentrations of aflatoxin B1 that were above the acceptable East African regulatory limit (5 µg kg-1). Although no statistically significant differences in mean aflatoxin B1 concentrations were found, exposure levels were notably higher in stunted vs. non-stunted children (53.7 vs. 46.5 ng kg-1 day-1). Findings were similar in regards to urinary aflatoxin M1 levels. All Lactobacillus strains showed the ability to bind aflatoxin B1 in saline, with L. fermentum APW1317 and L. casei APW2213C exhibiting the greatest binding capacity. Gut microbiota composition analyses revealed that among the bacterial genera identified in the fecal samples of 140 children, the genus Lactobacillus had the highest positive correlation to stunting (coefficient = 0.014).

Study results verify the high rates of aflatoxin exposure among children living in Uganda. An analysis of staple foods indicated high levels of contamination by aflatoxin B1, particularly in hulled maize flour, and was confirmed by the presence of aflatoxin M1 in urine samples. Isolated strains of Lactobacillus demonstrated the ability to effectively bind aflatoxin in vitro, and although no significant differences in abundance of Lactobacillus were apparent for stunted vs. non-stunted children, Lactobacillus as a genus showed the highest correlation to stunted growth. This unexpected finding of an inverse association between Lactobacillus and developmental growth warrants further investigation, but is hypothesized to be related to children’s transition from breastfeeding to a more plant-based diet (which could simultaneously increase Lactobacillus abundance and aflatoxin exposure). Limitations of the study pertain to its relatively small sample size of children and the need to verify the aflatoxin binding properties of Lactobacillus in physiological conditions more similar to those of the actual gut.

Source: Wacoo AP, Atukunda P, Muhoozi G, et al. Aflatoxins: occurrence, exposure, and binding to Lactobacillus species from the gut microbiota of rural Ugandan children. Microorganisms. 2020; 8: 347. DOI: 10.3390/microorganisms8030347.

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open accessarticle distributed under the terms and conditions of the Creative Commons Attribution(CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Click here to read the full text study.

Posted June 16, 2020.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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