Aflatoxin Occurrence, Food Regulations, Dietary Exposure, and Risk Assessment: A Mini Review from the Malaysian Perspective

@#Aflatoxins are ubiquitous and occur in food. Exposure to aflatoxins seriously impact the health of human and animal. It is concerning especially when aflatoxins are odourless, colourless, and tasteless that hardly be detected through naked eyes. Ingestion of aflatoxin-contaminated food contributes the major route of exposure. The present review is an update on the aflatoxin occurrence in food, aflatoxin regulations in food, and recent risk assessment of aflatoxin exposure in Malaysia. Peanuts and chili were more prone to aflatoxin contamination in Malaysia. The extreme weather experienced in Malaysia and global climatic change may worsen the aflatoxin contamination in food. The regulatory standards for aflatoxins imposed by Malaysia are less stringent than developed countries. The dietary exposure of aflatoxins among Malaysian was relatively high as compared with other Asia countries, ranging from 0.002 to 34.00 ng/kg body weight/day. Nonetheless, Malaysian population had low risk of aflatoxin-related liver cancer, with an estimated liver cancer risk of <1 cancer case/100,000 population/year.

Factors contributing to urinary aflatoxin M1 occurrence among residents in Hulu Langat district, Malaysia

@#Introduction: Chronic exposure to aflatoxin can lead to complications such as liver failure and cancer. There are many factors that affect aflatoxin occurrence. This study aimed to assess the association between sociodemographic factors and the knowledge, attitude and practice towards aflatoxin with urinary aflatoxin M1 occurrence among residents in Hulu Langat district, Malaysia. Methods: This was a cross-sectional study conducted among healthy Malaysian adults aged 18 to 60 years residing in Hulu Langat district, Malaysia. Socio-demographic background and the knowledge, attitude and practice of respondents towards aflatoxin were assessed through questionnaires. Non-fasting urine sample (15 ml) was collected in the morning and urinary aflatoxin M1 level was quantified. Results: Of the 444 healthy Malaysian adults, 199 urine samples were detected with aflatoxin M1. From 37 positive samples with aflatoxin M1 level above detection limit (0.64 ng/ml), mean value was 1.23±0.91 ng/ml (range = 0.65-5.34 ng/ml). Urinary aflatoxin M1 occurrence was significantly different across ethnicity, age group, monthly household income, attitude and practice towards aflatoxin. Binomial logistic regression confirmed ethnicity and monthly household income as factors contributing to urinary aflatoxin M1 occurrence. Chinese were 3.20 times more likely to have aflatoxin exposure than non-Chinese. Detected urinary aflatoxin M1 was more common among household with a monthly income above RM1,500. Conclusion: The results provided an insight to explain the variation in aflatoxin occurrence among the population.

Gut Microbiota Profiling of Aflatoxin B1-Induced Rats Treated with Lactobacillus casei Shirota.

Aflatoxin B1 (AFB1) is a ubiquitous carcinogenic food contaminant. Gut microbiota is of vital importance for the host's health, regrettably, limited studies have reported the effects of xenobiotic toxins towards gut microbiota. Thus, the present study aims to investigate the interactions between AFB1 and the gut microbiota. Besides, an AFB1-binding microorganism, Lactobacillus casei Shirota (Lcs) was tested on its ability to ameliorate the changes on gut microbiota induced by AFB1. The fecal contents of three groups of rats included an untreated control group, an AFB1 group, as well as an Lcs + AFB1 group, were analyzed. Using the MiSeq platform, the PCR products of 16S rDNA gene extracted from the feces were subjected to next-generation sequencing. The alpha diversity index (Shannon) showed that the richness of communities increased significantly in the Lcs + AFB1 group compared to the control and AFB1 groups. Meanwhile, beta diversity indices demonstrated that AFB1 group significantly deviated from the control and Lcs + AFB1 groups. AFB1-exposed rats were especially high in Alloprevotella spp. abundance. Such alteration in the bacterial composition might give an insight on the interactions of AFB1 towards gut microbiota and how Lcs plays its role in detoxification of AFB1.

The Binding Efficiency and Interaction of Lactobacillus casei Shirota Toward Aflatoxin B1.

The use of probiotic as dietary approach to prevent exposure to food contaminant, aflatoxin B1 (AFB1) has greatly increased. Several studies found that AFB1 binding to the bacterial cell wall is strain-specific. Moreover, the interaction between AFB1 and bacterial cell wall is not well-understood, thus warrants further investigation. This research was conducted to assess the ability of Lactobacillus casei Shirota (Lcs) to bind AFB1 at different concentrations and to determine AFB1 binding efficiency of different Lcs cell components including live cell, heat-treated, and cell wall. In addition, the interaction between AFB1 and Lcs was also evaluated via scanning electron microscopy (SEM) and through an animal study. The binding of AFB1 by all Lcs cell components depends on the concentration of available AFB1. Among all Lcs cell components, the live Lcs cells exhibited the highest binding efficiency (98%) toward AFB1. Besides, the SEM micrographs showed that AFB1 induced structural changes on the bacterial cell surface and morphology including rough and irregular surface along with a curve rod-shaped. In vivo experiment revealed that Lcs is capable to neutralize the toxicity of AFB1 on body weight and intestine through the binding process. The animal's growth was stunted due to AFB1 exposure, however, such effect was significantly (p < 0.05) alleviated by Lcs. This phenomenon can be explained by a significant (p < 0.05) decreased level of blood serum AFB1 by Lcs (49.6 ± 8.05 ng/mL) compared to AFB1-exposed rats without treatment (88.12 ± 10.65 ng/mL). Taken together, this study highlights the potential use of Lcs as a preventive agent against aflatoxicosis via its strong binding capability.

Mycotoxin: Its Impact on Gut Health and Microbiota.

The secondary metabolites produced by fungi known as mycotoxins, are capable of causing mycotoxicosis (diseases and death) in human and animals. Contamination of feedstuffs as well as food commodities by fungi occurs frequently in a natural manner and is accompanied by the presence of mycotoxins. The occurrence of mycotoxins' contamination is further stimulated by the on-going global warming as reflected in some findings. This review comprehensively discussed the role of mycotoxins (trichothecenes, zearalenone, fumonisins, ochratoxins, and aflatoxins) toward gut health and gut microbiota. Certainly, mycotoxins cause perturbation in the gut, particularly in the intestinal epithelial. Recent insights have generated an entirely new perspective where there is a bi-directional relationship exists between mycotoxins and gut microbiota, thus suggesting that our gut microbiota might be involved in the development of mycotoxicosis. The bacteria-xenobiotic interplay for the host is highlighted in this review article. It is now well established that a healthy gut microbiota is largely responsible for the overall health of the host. Findings revealed that the gut microbiota is capable of eliminating mycotoxin from the host naturally, provided that the host is healthy with a balance gut microbiota. Moreover, mycotoxins have been demonstrated for modulation of gut microbiota composition, and such alteration in gut microbiota can be observed up to species level in some of the studies. Most, if not all, of the reported effects of mycotoxins, are negative in terms of intestinal health, where beneficial bacteria are eliminated accompanied by an increase of the gut pathogen. The interactions between gut microbiota and mycotoxins have a significant role in the development of mycotoxicosis, particularly hepatocellular carcinoma. Such knowledge potentially drives the development of novel and innovative strategies for the prevention and therapy of mycotoxin contamination and mycotoxicosis.

Effect of dietary macronutrients on aflatoxicosis: a mini-review.

Aflatoxin is a toxin produced by Aspergillus species of fungi. The main route of aflatoxin exposure is through the diet. Indeed, long-term aflatoxin exposure is linked to the development of hepatocellular carcinoma (HCC). Aflatoxin causes aflatoxicosis, which can be affected by several factors and is prevalent in many developing Asian and African countries. This mini-review discusses the effects of carbohydrate, fat and protein on aflatoxicosis based on findings from animal and human studies. It was found that high carbohydrate intake enhanced aflatoxicosis occurrence, while low ingestion of carbohydrate with caloric restriction slowed the symptoms associated with aflatoxicosis. Additionally, diets with low protein content worsened the symptoms related to HCC due to aflatoxin exposure. Nevertheless, a study reported that a high-protein diet favored detoxification of aflatoxin in vivo. There were also conflicting results on the influence of dietary fat, as high ingestion of fat enhanced aflatoxicosis development as compared with a low-fat diet. Moreover, the type of fat also plays a significant role in influencing aflatoxin toxicity. In regard to food safety, understanding the influence of macronutrients toward the progression of aflatoxicosis can improve preventive measures against human and animal exposure to aflatoxin. © 2017 Society of Chemical Industry.

Effect of supplementation of fermented milk drink containing probiotic Lactobacillus casei Shirota on the concentrations of aflatoxin biomarkers among employees of Universiti Putra Malaysia: a randomised, double-blind, cross-over, placebo-controlled study.

Human exposure to aflatoxin is through the diet, and probiotics are able to bind aflatoxin and prevent its absorption in the small intestine. This study aimed to determine the effectiveness of a fermented milk drink containing Lactobacillus casei Shirota (LcS) (probiotic drink) to prevent aflatoxin absorption and reduce serum aflatoxin B1-lysine adduct (AFB1-lys) and urinary aflatoxin M1 concentrations. The present study was a randomised, double-blind, cross-over, placebo-controlled study with two 4-week intervention phases. In all, seventy-one subjects recruited from the screening stage were divided into two groups--the Yellow group and the Blue group. In the 1st phase, one group received probiotic drinks twice a day and the other group received placebo drinks. Blood and urine samples were collected at baseline, 2nd and 4th week of the intervention. After a 2-week wash-out period, the treatments were switched between the groups, and blood and urine samples were collected at the 6th, 8th and 10th week (2nd phase) of the intervention. No significant differences in aflatoxin biomarker concentrations were observed during the intervention. A within-group analysis was further carried out. Aflatoxin biomarker concentrations were not significantly different in the Yellow group. Nevertheless, ANOVA for repeated measurements indicated that AFB1-lys concentrations were significantly different (P=0·035) with the probiotic intervention in the Blue group. The 2nd week AFB1-lys concentrations (5·14 (SD 2·15) pg/mg albumin (ALB)) were significantly reduced (P=0·048) compared with the baseline (6·24 (SD 3·42) pg/mg ALB). Besides, the 4th week AFB1-lys concentrations were significantly lower (P<0·05) with probiotic supplementation than with the placebo. Based on these findings, a longer intervention study is warranted to investigate the effects of continuous LcS consumption to prevent dietary aflatoxin exposure.

A mini review on aflatoxin exposure in Malaysia: past, present and future.

This mini review article described the exposure of aflatoxin in Malaysia, including its presence in the foodstuffs and the detection of aflatoxin biomarkers in human biological samples. Historically, the exposure of aflatoxin in Malaysia can be dated in 1960s where an outbreak of disease in pig farms caused severe liver damage to the animals. Later, an aflatoxicosis case in Perak in 1988 was reported and caused death to 13 children, as up to 3 mg of aflatoxin was present in a single serving of contaminated noodles. Since then, extensive research on aflatoxin has been conducted in Malaysia. The food commodities such as peanuts, cereals, spices, and their products are the main commodities commonly found to be contaminated with aflatoxin. Surprisingly, some of the contaminated foods had levels greater than the permissible limit adopted by the Malaysian Food Regulation 1985. Besides, exposure assessment through the measurement of aflatoxin biomarkers in human biological samples is still in its infancy stage. Nevertheless, some studies had reported the presence of these biomarkers. In fact, it is postulated that Malaysians are moderately exposed to aflatoxin compared to those high risk populations, where aflatoxin contamination in the diets is prevalent. Since the ingestion of aflatoxin could be the integral to the development of liver cancer, the incidence of cancer attributable by dietary aflatoxin exposure in Malaysia has also been reported and published in the literatures. Regardless of these findings, the more important task is to monitor and control humans from being exposed to aflatoxin. The enforcement of law is insufficient to minimize human exposure to aflatoxin. Preventive strategies include agricultural, dietary, and clinical measures should be implemented. With the current research on aflatoxin in Malaysia, a global networking for research collaboration is needed to expand the knowledge and disseminate the information to the global scientific community.

Association between aflatoxin M1 excreted in human urine samples with the consumption of milk and dairy products.

This study aimed to find the association between urinary aflatoxin M(1) level and milk and dairy products consumption. Of 160 morning urine samples collected, aflatoxin M(1) was detected in 61.3 % samples (n = 98) [mean ± SD = 0.0234 ± 0.0177 ng/mL; range = 0-0.0747 ng/mL]. Of these positive samples, 67.3 % (n = 66) had levels above the limit of detection. Respondents with intake of milk and dairy products above median (67.79 g/day) had significantly high level of AFM(1) compared to those with low intake. A significant and positive association (φ = 0.286) was found between milk and dairy products consumption and urinary aflatoxin M(1) level.