The perils of peanut butter
DANGEROUS SPREAD: WHAT ARE AFLATOXINS AND WHY DO THEY POSE A HEALTH THREAT?
Product recall highlights the issue of contamination.
Various brands of peanut butter were recalled over the past week because the supplier found that they may contain levels of aflatoxins that exceed regulatory limits. This has many consumers wondering what aflatoxins are, how they got into the peanut butter and why they are dangerous.
According to an article by Anelich Consulting which specialises in food safety, certain food commodities are prone to aflatoxin contamination. The article addresses the matter of aflatoxins in food after the latest peanut butter recalls in the country.
The National Consumer Commission said this week that the company, House of Natural Butters, produced several brands of peanut butter that were recalled. Anelich Consulting says it is important that consumers stop eating these products and return them as instructed.
Food safety expert Prof Lucia Anelich says in the article that aflatoxins are a group of toxins produced by several fungi, but most notably, Aspergillus flavus and Aspergillus parasiticus, that are found naturally in the environment as most other fungi.
“They can be present on different crops such as cottonseed, maize, rice, some spices, cocoa beans, tree nuts and peanuts while growing in the field. The aflatoxins are then produced by the fungi, mainly when these commodities are stored incorrectly in warm and humid conditions after harvesting.”
She says in some cases, the toxins are produced in the commodities while still in the field and even figs have been contaminated with aflatoxins.
“The four major naturally produced aflatoxins are called B1, B2, G1 and G2. A. flavus produces B1 and B2 while A. parasiticus produces B1, B2, G1 and G2. Of all four types of aflatoxins, B1 is the most toxic.
“Another one is M1 which is similar to B1 (and so is not considered an additional type). Humans are exposed to M1 practically exclusively through milk and milk products, including breast milk.”
Aflatoxins are potent liver carcinogens, capable of causing cancer in all animal species studied, including humans, Anelich says.
“However, an important point to make is that one of the most important concepts when dealing with any toxin is dosage.”
She says Paracelsus said in 1538: “All things are poison and nothing is without poison; the dosage alone makes it so a thing is not a poison.” This is often condensed to “the dose makes the poison”. It means that a substance can produce the harmful effect linked to its toxic properties only if it reaches a system in the body that’s vulnerable to that toxin in a high-enough concentration.
“It is estimated that around 4.5 billion of the world’s population (more than half of the its current population), mainly in developing countries, is exposed to aflatoxins. Because aflatoxins are found so abundantly across many staple foods in developing countries, one could be exposed to low levels over a long period of time,” Anelich says.
This continuous exposure at low levels is known as chronic exposure and can be the cause of liver cancer many years later, estimated at around 20 years later.
Is there a “safe” level for afla“There is currently no zero level possible for aflatoxins in susceptible commodities although that would be the ideal,” she says.
“Therefore, there are regulatory limits in place in most countries for these commodities, with the express aim to limit exposure to these toxins through food and animal feed.”
South Africa follows the limits proposed in the relevant Codex Alimentarius Commission standard, a joint Food and Agriculture Organisation/World Health Organisation body. South African regulatory limits as per the relevant regulation R1 145, are a maximum of 15 micrograms/kg (parts per billion or ppb) of total aflatoxins in peanuts intended for further processing (for example, to make peanut butter).
A maximum of 10 micrograms/ kg (ppb) of total aflatoxins, of which a maximum of five micrograms/kg of aflatoxin B1 is the limit for all foodstuffs ready for human consumption and a maximum of 0.05 micrograms/litre (ppb) of aflatoxin M1 in milk.
What types of illnesses do aflatoxins cause? Anelich says there are two categories of effects when people eat food contaminated with aflatoxins.
“The first is known as acute aflatoxicosis (poisoning through aflatoxins), where extremely high levels of the toxin are eaten. However, these cases are very rare, but when they do occur, liver failure results and people die. There have been three notable incidents: in India in 1974 and in Kenya in 1981 and 2004, all from consuming excessively contaminated maize.”
In these cases, death can occur within days. Anelich says what is evident from these poisonings and the research work done on them is that the victims had very little else to eat and ate not only highly contaminated food, but large amounts of it, which means that their portion sizes and frequency of eating the contaminated food were very high.
She says it is important to note that until now, there have not been acute aflatoxicosis cases reported related to eating peanuts or peanut-based products.
“The second category of aflatoxicosis is known as chronic exposure when someone is exposed to lower levels of aflatoxin over a longer period. The effects are varied, with liver cancer being the most prominent possible outcome. Other effects include suppression of the immune system and growth-stunting in children.”
She points out that aflatoxin can cross the placental barrier and affect the foetus and exposure after birth would exacerbate the stunting.
Many factors play an important role in understanding the potoxins? tential effects. All of these need to be considered when determining possible outcomes, Anelich says that:
The age of the individual (children are more seriously affected);
The health status of the individual (any underlying conditions such as hepatitis B which is the leading cause of liver cancer worldwide);
The weight of the individual; The nutritional status of the individual;
The variety in the diet of the person (if you eat mainly maize or peanuts with very little variety in your diet, you are more susceptible to aflatoxin effects);
The frequency of consumption (how many times a day/week/ month you eat it);
Portion size (as levels of aflatoxin are presented as micrograms/kg of product (ppb) as eating a certain portion size will also determine how much aflatoxin you eat at a sitting); and
The period of time over which you eat the contaminated food.
“Furthermore, inherent genetic differences across the human population may also result in different reactions or differences in the severity of reactions. Evaluating all these factors forms an important part of conducting a risk assessment to quantify the magnitude of exposure and the subsequent probability of a harmful effect to affected people,” she adds.
In some cases, the toxins are produced in the crops while they are still in the field