Food fraud – fake honey

Food fraud is nothing new, but the intensity and frequency have been on the rise. From counterfeit extra-virgin olive oil to intentional adulteration of spices and the manufacturing of fake honey, food fraud has been estimated to be a $US40 billion a year industry. In a series of posts we will cover a range of recent issues.

First cab off the rank is fake honey.

honey_(Hillary_Stein)The brutal reality is adulterated honey is big business. It is all too easy to cheat by diluting honey with cheap sugar syrup substitutes, such as rice syrups, corn syrups, high fructose corn syrups and acid inverted sugar syrups. It can also be adulterated with natural syrups such as maple, cane sugar and molasses.

This is nothing new as food fraud experts point out that honey is one of the most commonly mislabelled foods around the world. After enough scandals involving cheap adulterated Chinese honey flooding the American market, the US Federal Trade Commission imposed stiff tariffs on Chinese honey in 2001 to try to stop it from being imported. That just meant that the Chinese honey was laundered through other Asian and some European countries before finding its way to the American market.

A new scandal erupted in mid 2018 as researchers determined that almost half the honey sold on Australian supermarket shelves was fake honey.

China is a common source for the sugar syrup culprits with Chinese websites selling them with claims that they can pass various official honey tests (see below).

Destroying the good name of honey

Humans have been harvesting honey for more than 6,000 years. It has been used as both a food and a medicine. Historically, people have used it to sweeten food and make fermented beverages like mead. Today it is also used in industrial food processing of baked products, confectionary, candy, marmalades, jams, spreads, breakfast cereals, beverages, milk products and many preserved products.

Honey is also considered to carry health properties. It contains a number of antioxidants, including phenolic compounds like flavonoids, that have been linked to reduced risk of heart attacks, strokes and some types of cancer.

Honey seems to have a positive effect on cholesterol levels. It leads to modest reductions in total and “bad” LDL cholesterol while raising “good” HDL cholesterol. Several studies show that honey can lower triglyceride levels, especially when used as a sugar substitute.  Elevated triglycerides are a risk factor for heart disease and type 2 diabetes.

Honey also has antimicrobial properties. When applied to the skin, honey can be part of an effective treatment plan for burns, wounds and many other skin conditions. It is particularly effective for diabetic foot ulcers.

For children over one year of age, honey can act as a natural and safe cough suppressant. Some studies show that it is even more effective than cough medicine.

Destroying the business for beekeepers

Honey_bee_(Jon_Sullivan)Substituting cheap sugar syrups for honey would negate many of the positive properties of honey. If that is not bad enough it makes it difficult for beekeepers to compete and threaten the survival of bees. No bees – a starving world, it’s as simple as that.

Bees and other pollinators fertilise three-quarters of global food crops and have seen severe declines in recent decades, due to loss of habitat, disease and harmful pesticides. In the UK, wild honey bees are nearly extinct, solitary bees are declining in more than half the areas studied and some species of bumblebee have been lost altogether.

The large bee losses reported worldwide over the last decades have stimulated a lot of research on the monitoring of bees and the potential causes of the losses including pathogens, pests, diseases, nutrition, pesticides, habitat and climate changes. During this process, extensive datasets have been generated and collated on honeybee losses that have been linked to diseases, pests and pathogens in Europe and North America. Less is known about the situation for solitary bees and bumblebees.

Fake honey is a further nail in the coffin.

Beating the cheaters

Many of the syrups sold by the Chinese promises to be able to beat what’s called a C4 sugar test, which is the official test used in Australia and many other countries for testing of honey adulteration.

Sugars produced from tropical plants like sugar cane and maize/corn are produced using a photosynthetic pathway referred to as the C4 pathway.  Nectar which is collected by bees comes from plants that use a different process of photosynthesis, referred to as the C3 pathway.  There is a measurable difference in the ratio of the naturally occurring carbon-12 and carbon-13 isotopes in sugars arising from the C3 and C4 pathways, and this test uses this difference to identify whether C4 sugar appears to have been added to the honey.

nmrBut what to do when the cheaters even cheat the test? Well, there is a method called “Nuclear Magnetic Resonance” (NMR for short). The nuclei in atoms have electrical charges, and many also have a physical property known as spin. This means they are sensitive to magnetic fields in NMR machines with the nuclei of each type of atom reacting differently. By measuring how the nuclei in the sample respond to different magnetic fields a fingerprint of what is in the sample is created.

NMR is a very sensitive technique already used in other parts of the food industry, such as testing fruit juices and wines. In honey, it can distinguish between the different types of sugars and detect other components that give honey its unique flavours. It is a relatively new method that may be adopted by official bodies in the future.

A brighter future

There is hope that honey adulteration might become a cheat of the past with the new analytical methods. This will allow honey consumers to enjoy their passion and beekeepers to secure their future.

And bees will be allowed to perform their work benefiting the worlds food crops.

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Can honey make you sick?

honey_(Hillary_Stein)

The safety of honey questioned (Photo: Hillary Stein)

Is the world mad when Irish scientists focus their attention on Australian honey and find high levels of pyrrolizidine alkaloids? And the results are sensationalised by the Australian press a year later, talk about a slow response! Headlines in January 2016 proclaimed that “Australian honey could make us sick” and the article stated that “Australian honeys are the most contaminated in the world with natural poisons linked to chronic disease including cancer”. If that didn’t frighten you, what would?

And truely, pyrrolizidine alkaloids are natural toxins linked to chronic disease including cancer. Typically the compounds affect the liver and in some cases the lungs causing serious illness. Animal experiments have also shown that certain pyrrolizidine alkaloids are genotoxic carcinogens, the worst of the worst of toxins.

So what are they?

Pyrrolizidine alkaloids are produced as a protection against herbivores by about 6,000 plant species, representing 3% of all flowering plants, most of which are weeds. There is a great variety of compounds with more than 500 different pyrrolizidine alkaloids known to date. Besides in honey, pyrrolizidine alkaloids in food have been detected in products of plant origin, for example, in herbal teas and supplements, cereals, and salads. Cases of elevated contamination in wheat are known to have occurred in Afghanistan associated with illness and similarly contaminated salad in Germany.

To be fair to the Irish, the study was all about developing better analytical methods for detecting multiple pyrrolizidine alkaloids and the scientists probably selected Australian honey to be certain of having positive samples. They could as well have selected South American samples also known for containing high levels of pyrrolizidine alkaloids.

Nevertheless, their results showed that 41 of the 59 honey samples were contaminated by pyrrolizidine alkaloids with a mean total sum of 153 µg/kg. This is on average four times more pyrrolizidine alkaloids than in European honeys and is quite high as an average level. Echimidine and lycopsamine were most common and found in 76% and 88%, respectively, of the positive samples. The scientists also attempted to calculate possible average daily exposure based on the results and found that adults could have an exposure of 0.051 µg/kg bodyweight per day and children 0.204 µg/kg bodyweight per day of pyrrolizidine alkaloids.

What does it mean?

It is debatable if all pyrrolizidine alkaloids should be treated equally when considering their toxicity due to their expected cumulative effects or if some of the compounds could be considered to be less toxic.

laboratory

Scientists cannot agree on how to assess safety of honey.

Conveniently the Australian authority, Food Standards Australia New Zealand, considers that echimidine is less toxic and used a Tolerable Daily Intake approach in establishing a safe level of exposure of 1 µg/kg bodyweight per day. This was calculated by applying an uncertainty factor of 10 to what was considered to be a human no-observed-effect level of 10 µg/kg bodyweight per day for liver failure due to veno-occlusive disease. But carcinogenic effects were not considered. Using this approach the Irish exposure estimates are well within safe limits.

Not so says a number of national and international organisations like the World Health Organization International Programme on Chemical Safety, the Dutch Rijksinstituut voor Volksgezondheid en Milieu, the UK Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment, the German Bundesinstitut für Risikobewertung, and the CONTAM Panel of the European Food Safety Authority. They have all concluded that 1,2-unsaturated pyrrolizidine alkaloids may act as genotoxic carcinogens in humans (that is they may cause cancer and damage DNA, the genetic material of cells).

The safety of genotoxic carcinogens should be evaluated using the Margin of Exposure approach and not the Tolerable Daily Intake approach. A benchmark dose lower confidence limit for a 10% excess cancer risk (BMDL10) of 70 μg/kg bodyweight per day for induction of liver haemangiosarcomas by lasiocarpine in male rats was calculated as the reference point for comparison with the estimated dietary exposure. As a Margin of Exposure of 10,000 or higher, based on a BMDL10 from an animal study, is considered to be of low concern from a public health point of view, exposure to 0.007 µg/kg bodyweight per day or less of pyrrolizidine alkaloids would not be a worry. But the Irish presented much higher exposure estimates.

What margin is safe?

The different interpretations of what is a safe exposure to pyrrolizidine alkaloids is confusing to scientists and the public alike. Honey consumption has a long and varied history as a remedy for several health afflictions. Although, due partly to low numbers and questionable quality of human studies, some of the suggested health benefits of honey have been difficult to prove scientifically. Nevertheless, the public perception is that honey is a wholesome and natural product beneficial to health and a tastier alternative to refined sugar. There is a small committed group of consumers that regularly consume relatively large amounts of honey. So the findings of pyrrolizidine alkaloid contamination is disturbing.

Patersons

Paterson’s curse is a common source of pyrrolizidine alkaloids in honey.

However, there are som alleviating factors to reassure honey consumers. The presence in honey of lasiocarpine used to calculate the BMDL10 is rare and most other pyrrolizidine alkaloids are at least a magnitude less toxic. This could raise the level of exposure of no concern to 0.07 µg/kg bodyweight per day. Also retail honeys are often mixed from several sources to reduce the overall level of pyrrolizidine alkaloids in the consumer-ready product. And finally the Australian honey industry is claiming that they have reduced access of bees to Paterson’s curse, a main source of pyrrolizidine alkaloids in Australian honey. But the future will tell if that is right.

So some caution is justified for regular honey consumers. Vary your source of honey to limit exposure and hopefully you will be fine. For now.

 

The hard working bee

Bee collecting pollen and nectar (Photo: Wikimedia

Bee collecting pollen and nectar (Photo: Wikimedia

Bees are hard at work collecting pollen and nectar to feed themselves and their off-spring. When foraging for food they use the sun for direction, initially using a somewhat irregular path away from the hive to find a suitable source up to 10 km away. The bee will then fly a straight line back to the hive and perform a dancing act to indicate the shortest way to the source for other bees. Many bees will then fly a straight path to the source the original bee found and will repeat the process themselves.

The foraging bees regurgitate nectar and pass it to worker bees in the hive. In order to conserve space and preserve their food, bees transform the nectar into honey by evaporating most of the water from it. Nectar is as much as 70 percent water, while honey is only about 20 percent water. Bees get rid of the extra water by swallowing and regurgitating the nectar over and over. They also fan their wings over the filled cells of the honeycomb. This process retains lots of sugar and the plant’s aromatic oils while adding enzymes from the bees’ mouths.

Honey as human food

Honey is ancient food (Photo: Hillary Stein)

Honey – an ancient food (Photo: Hillary Stein)

Humans have been harvesting honey for more than 6,000 years for our own use. Historically, people have used it to sweeten food and make fermented beverages like mead. Today it is also used in industrial food processing of baked products, confectionary, candy, marmalades, jams, spreads, breakfast cereals, beverages, milk products and many preserved products.

Honey’s high sugar content, flavour and antimicrobial properties make it a useful ingredient. It is also considered to carry health properties.

So far so good making this a good news story. But of course there has to be a negative side to the story as well otherwise it wouldn’t be covered on this food safety blog. And now we come to my own challenge spelling the name of the chemical substance group that can be present in honey and pose a threat to public health. With the dictionary in one hand and typing with the other I want you to be aware of pyrrolizidine alkaloids.

Pyrrolizidine alkaloids are a group of naturally occurring substances that are produced by plants as a defense mechanism against predator attacks.

Pyrrolizidine alkaloids in honey

There are more than 600 different pyrrolizidine alkaloids identified in over 6,000 plants. About half of them are toxic to humans and other animals, mainly damaging the liver or in some cases even causing liver cancer. In an opinion published in 2011, the European Food Safety Authority nominated some pyrrolizidine alkaloids as genotoxic carcinogens. It has been estimated that three percent of the world’s flowering plants contain pyrrolizidine alkaloids, mostly members of the daisy, forget-me-not or borage families as well as the legume family. And unfortunately the pyrrolizidine alkaloids can find their way into honey.

Ragwort a source of pyrrolizidine alkaloids (Photo: Wikimedia)

Ragwort a source of pyrrolizidine alkaloids (Photo: Wikimedia)

Plants that commonly contribute to pyrrolizidine alkaloid contamination of honey include Echium, Senecio and Borago species whose pollen might be used for honey production by the bees. In Australia, the toxins may get into the honey when bees forage on the flowers of Paterson’s Curse, also known as Salvation Jane. Raw honeys from certain countries in Central and South America, Cuba and Uruguay in particular, and Australia and New Zealand show higher levels of pyrrolizidine alkaloids compared to raw honeys from some European and Asian countries.

For most people who eat small amounts of honey, the levels of pyrrolizidine alkaloids would be well below the tolerable daily intake and not a cause for concern. However, chronic effects cannot be excluded and are often difficult to associate with a particular food source. It is thus recommended that anyone who daily eats more than two tablespoons of honey should be careful in not selecting an exclusive product source.

Most honeys are mixed before retail to reduce the levels of pyrrolizidine alkaloids and this reduces potential risks.

Other sources of pyrrolizidine alkaloids

In addition to honey, there are other potentially more important sources of dietary exposure to pyrrolizidine alkaloids. The majority of reports of acute outbreaks of pyrrolizidine alkaloid poisoning have largely been limited to third world countries. Generally, these have been outbreaks where hundreds, and sometimes thousands, have been poisoned from eating staple foods made from cereal crops contaminated with seeds from pyrrolizidine alkaloid-containing weeds. For example, people were taken ill in Pakistan, India and Afghanistan after eating wheat contaminated with seeds from Heliotropium or Crotalaria species. In Jamaica, cases of poisoning have occurred through so-called bush teas containing Crotalaria and parts of the ragwort plant.

More recently, along with an increasing reliance on unconventional medicine and the use of herbal supplements, notably borage leaf, comfrey and coltsfoot, there has been a rise in the number of poisonings seen in industrialised countries. Also Borage oil and Echium oil marketed as dietary supplements, and salad crops contaminated with ragwort or common groundsel could present a risk to the consumer.

Take care

It is believed that the real extent of human poisoning by pyrrolizidine alkaloids has been underreported since the cause of chronic diseases are difficult to establish. So watch your honey consumption and stay away from suspect dietary supplements.

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