HONEY - from "nectar of the gods" to honey toxicity? - myth and reality (1)
Dr. Mirela Stranț, Cluj Napoca, doctor competent in apiphytotherapy, Reader in Ayurveda AMN-Romania
Bee honey was the first sweet substance used by man.
Since ancient times, man has discovered honey and hive products not only as food, but also as a remedy. Despite all the exceptional qualities of honey, there is a mass belief (often greatly exaggerated) that honey can be toxic under certain conditions! Even scientists have studied this and conducted various laboratory experiments to clarify this.
In short, there are certain varieties of potentially toxic herbal honey which, consumed continuously or in larger quantities, can have unpleasant effects on the body or can sometimes lead to poisoning.
There is also a risk of contamination by pesticides or heavy metals. On the other hand, there is some concern about heat treatments applied to honey.
Exposure to temperatures above 37 degrees Celsius will induce changes in the composition of honey, losing some therapeutic qualities and also forming some new substances, such as hydroxymethylfurfural (HMF), but HMF is formed in much greater quantities in bakery products, dried fruit and many other processed foods.
Therefore, sweetening tea (even very hot tea) with a teaspoon of honey will not cause as much damage as if we use the same amount of sugar, or worse, artificial sweeteners, and it certainly won't make us sick with who knows what mysterious disease ...
In order to shed light on this important issue, several aspects will be analysed and compared, concerning those related to the consumption of honey but also other foods frequently used in the diet.
The extraordinary qualities of honey - both a medicine and a valuable food - have been known since ancient times. Originally, honey was rare, being reserved for religious service, the worship of the gods or the feeding of sacred animals. The Babylonians and the various ancient civilisations of India and China used honey both as a medicine and in rituals and ceremonies.
In the Old Testament we find the word "honey" written more than 60 times. The Thracians called honey living food.
Ancient Greco-Roman writings are full of references to bee honey and its medicinal use, creating a veritable mythology around it and highlighting its many beneficial properties.
Muslims used honey as a good remedy against any disease. Aristotle wrote six volumes on bees and their products. Hippocrates, the first ancient physician, and later Pliny, Galen and Dioscorides, also speak of honey.
Honey is very often used in food, in cooking or as a remedy, being highly valued in traditional medicine.
It also has important applications in artificial nutrition, pre- and post-operative nutrition, paediatrics and gynaecology.
Because of its nutritional qualities, bee honey is considered a valuable food in the diet of people of all ages, with wide uses in dietetics and therapeutics. The nutritional value of honey lies mainly in its richness in sugars (70-80%), from this point of view, being an energy food par excellence.
Most of the sugars contained in honey are simple sugars (glucose and fructose), which no longer require special processing through digestion, being directly assimilated and completely burned (unlike sugar), this energy being entirely available to the body, making honey an easily assimilated and digestible food.
It does not use vitamin B, calcium and magnesium stores for absorption, as is the case with sugar, especially refined sugar, and is not addictive (like sugar).
On the other hand, it strongly supports the immune system, whereas every time sugar is consumed, 70% white blood cells responsible for immune defence enter a state of "lethargy". It also has anti-inflammatory effects (whereas sugar is a powerful pro-inflammatory), and some studies also show anti-tumour effects of honey.
Supports the optimal functioning of the digestive tract and the formation of "good" bacteria in the intestines (the latest studies show the enormous influence that a healthy intestinal flora has on physical, mental and emotional health), has exceptional healing and regenerative effects, being a well-known Ayurvedic Rasayana (rejuvenating) and Vajikarana (aphrodisiac) remedy in addition to the many other therapeutic effects it has.
The essential difference between honey and commercial sugar is its high content of certain non-sugar substances (microelements, enzymes, organic acids and vitamins), which exert their positive effect by adjusting important functions in the body.
Honey contains hundreds of organic substances, a complex mixture of nitrogen compounds, lactones, proteins, is rich in substances with an antibiotic effect - inhibins, enzymes, phenolic antioxidants, aromatic compounds, amino and organic acids, gluconic acid, phenolic acids, flavonoids, minerals, vitamins and other phytochemical compounds (sodium, potassium, phosphorus, magnesium, copper, aluminium, manganese, iron, chlorine, sulphur, silicon) as well as certain trace elements: beryllium, gallium, vanadium, zirconium, titanium, nickel, tin, lead, silver). Vitamins and minerals vary according to the nectar used by the bees and finally vary according to the soil resources on which the plants grow. Used at breakfast, it is a source of energy that helps the body get a good start to its daily activity.
Can honey be toxic?
Despite all the exceptional qualities of honey, there is a mass belief (often greatly exaggerated) that honey can be toxic under certain conditions! Even scientists have studied this and conducted various laboratory experiments to clarify.
Of course, there are some varieties of honey from potentially toxic plants, such as Dhatura or rhododendron (these honeys are not present in Romania anyway) which contain alkaloids that can give unpleasant reactions when consumed in larger quantities. Or there is a situation where honey can be contaminated with heavy metals. In addition, external characteristics such as seasonal and environmental factors, duration and conditions of processing and storage of honey have crucial effects on its composition.
First, let's look at the most common concern people have: heating honey.
English translations of ancient Ayurvedic texts mention that honey can become toxic at high temperatures, so modern scientists have set to work testing this hypothesis and in this article we will explore their research. Beyond that, common sense can save us from many misunderstandings and unfavourable decisions.
For example, if we think of the teaspoon of honey put in hot tea or in various preparations that use high temperatures, common sense should tell us that this is a much better option than using sugar, rightly called "white death" or artificial sweeteners such as aspartame - one of the most harmful food additives, found in abundance in many food products, light drinks, medicines and syrups for children and adults, etc.
Going back to honey and what happens when it is heated, especially at high temperatures, the first thing to note is that enzymes will be inactivated, proteins and vitamins denatured, the lactobacilli destroyed which will greatly reduce the therapeutic properties of honey (important to know when we use honey for its healing effects) but it doesn't cause any horrible diseases and you won't be poisoned if you consume a teaspoon of honey with a cup of hot tea, and certainly no one will die from it.
As for the nutritional benefits of honey - yes, heating honey can damage them, honey digestion can be slowed down due to the destruction of their own enzymes (but this happens with any thermally prepared food).
Heating honey can lead to the loss of thermolabile compounds such as vitamins, enzymes and essential amino acids (lysine, tryptophan) but also to the formation of undesirable compounds and a reduction in flavour.
Particular attention has been paid to the formation of compounds which do not occur naturally in honey and which, in large quantities, could have negative health effects such as: heterocyclic amines, nitrosamines and polycyclic aromatic hydrocarbons.
A cyclic aldehyde formed from carbohydrates. Although HMF is present at very low concentrations and may even be absent in fresh honey, heat treatment and/or prolonged storage conditions may increase HMF production. But HMF is not only present in honey, there are no heat-treated foods that do not contain HMF.
It is almost ubiquitous in various concentrations in our daily heat-processed foods containing carbohydrates, from breakfast cereals, breads, dairy products and dried fruit, to fruit juices to coffee and liqueurs.
One of the most interesting compounds is hydroxy-methyl-furfural (HMF), a cyclic aldehyde formed from carbohydrates. It occurs spontaneously in carbohydrate-rich foods due to the Maillard reaction (non-enzymatic caramelisation reaction) or due to acid-catalysed dehydration of hexoses (e.g. glucose, fructose). Since HMF is absent from fresh, unprocessed foods, but has an increased concentration in the case of heat treatment or long-term storage, it is used as an indicator of freshness and quality of honey.
The formation of HMF in honey
Several factors influence the formation of HMF in honey during storage: the use of metal containers (stainless steel, aluminium cans, etc.), the physico-chemical characteristics of the honey (pH, total acidity, lactone and mineral content) related to the floral source of the honey from which it comes, humidity, thermal and photochemical stress.
Under acidic conditions, HMF can form at low temperatures, but it occurs when temperature and storage time increase. In addition, the appearance of HMF is also related to the water content of the honey. A low percentage of water in honey is correlated with inhibition of HMF formation.
Here it is important on the one hand to harvest the honey only after it has ripened and to store it in good condition in hermetically sealed containers (non-metallic, non-plastic), protected from excessive heat and direct sunlight. .
A higher concentration of HMF indicates poor storage conditions and/or excessive heating of the honey. The rate of HMF formation also depends on the fructose:glucose ratio and the type of sugars formed, as it has been reported that at pH=4.6 fructose is five times more reactive than glucose, which means that honeys rich in fructose, such as acacia and chestnut, form HMF faster than glucose-rich honey (which crystallises quickly) such as lime honey, black grass, rapeseed, polyflora or buckwheat.
However, although HMF occurs at very low concentrations and may even be absent in fresh honey, heat treatment and/or prolonged storage conditions may increase HMF production.
For example, some studies have reported that the average concentration of HMF in honey from Malaysia (tropical country) stored for 2 months at 4-5°C was 35.98 mg/kg, but stored at 25-30°C for more than a year could reach levels of 118.47 to 1139.95 mg/kg).
Therefore, the Codex Alimentarius Commission has set the maximum limit for HMF in honey at 40 mg/kg (with an upper limit of 80 mg/kg for honey from tropical regions) to ensure that the product has not undergone extreme heating during processing and is safe for consumption.
HMF in other foods
But HMF is not only present in honey! It is almost ubiquitous in various concentrations, in our daily heat-processed carbohydrate foods, from breakfast cereals, breads, dairy products and dried fruit, to fruit juices to coffee and liqueurs. HMF is also present in dried fruit (> 1000 mg/kg), ripe foods, tomato products, products containing caramel, instant coffee (up to 6200 mg/kg), apple juice, citrus juices, vinegar, beer, brandy, etc. and HMF is released from sugar and carbohydrates even after cooking at home, indicating that HMF is ubiquitous in our diet. Most of these foods are subjected to heat treatments before consumption, such as boiling, baking, extrusion cooking, frying, pasteurisation and other treatments.
According to Norwegian and German scientists, cereals and cereal products, including bread, are among the most important sources of human exposure to HMF, due to the amount consumed daily. In addition, the formation of HMF in cereal products is largely dependent on many factors, including temperature, the dough fermentation process, water activity and the presence of fruits, berries and other flavourings or additives.
Mańkowska and colleagues studied HMF levels in 41 foods, with wheat bread with cranberries containing the highest amount of HMF (210 mg/kg), followed by breakfast cereals with wheat and honey (85.09 mg/kg).
The lowest amount of HMF was reported in gluten-free cakes and whole grain oatmeal. Sweetened breakfast cereals contained HMF at 25.55 mg/kg, which was higher than the average HMF concentration (18.40 mg/kg) in bakery products.
In other studies, it was found that among cereals, the highest producers of HMF are wheat (up to 132 mg/kg) and cornflakes (up to 114 mg/kg). In the case of bread, HMF values vary widely, from 3.4 to 176.1 mg/kg, depending on fermentation conditions, added leavening, crust and breadcrumb thickness and type of bread (oat bread, white bread or wheat bread).
Different types of dried fruit (raisins, blueberries, dates, strawberries, redcurrants and apples) are added to cereal products.
The lowest concentration (6.06 mg/kg) of HMF was reported in crunchy products containing raisins and plums. On the other hand, red fruits such as red apples, strawberries and redcurrants as well as dried dates have high concentrations of HMF.
The high carbohydrate content and high drying temperatures certainly contribute to this.
Researchers Murkovic and Pichler analysed HMF concentrations in dried apricots, peaches, pears, figs, dates, apples and pineapples. HMF concentrations were highest in dates (1000 mg/kg) and plums (1100-2200 mg/kg). The average range of HMF concentrations in other nuts was 1-780 mg/kg. In contrast, in a study on commercially dehydrated vegetables, HMF was not detected, except in cabbage, tomatoes and artichokes (58.60; 18.20 and 6.97 mg / kg respectively).
In the case of dairy products, HMF is formed by side reactions during heat sterilisation and browning processes and shelf life. In traditional Indian dairy products, there was a strong positive correlation between HMF concentration and the flavours, colours and textures of their products. In fact, infant formula contains up to 15 times more HMF than liquid milk.
The concentration of oil in products can also affect the formation of HMF. To investigate this hypothesis, roasted and ground or caramelised peanuts were studied. Peeled peanuts fried in large amounts of oil and for a long time (30-60 minutes) showed increased HMF formation (66.5-144.0 mg/kg). The situation is even more dramatic in the case of caramelised peanuts - 372 mg HMF / kg.
In the light of this information, we can conclude that there are no heat-treated foods that do not contain HMF.