HONEY - from "nectar of the gods" to honey toxicity? - myth and reality (2)
Dr. Mirela Stranț, Cluj Napoca, doctor competent in apiphytotherapy, Reader in Ayurveda AMN-Romania
Comparison of HMF levels in honey with other foods
As we already know, HMF is not naturally present in food but is formed after heat treatment and in combination with other factors as there is no fixed concentration of HMF in different foods. Cooking temperature, the rate of sucrose degradation, concentration of reducing sugars, type of sugar (glucose, fructose or other), water activity, addition of other food additives such as sweeteners containing HMF, colours, caramelisation, storage time and temperature, the type of storage and treatment of metals varies considerably from one food to another. As a result, the HMF content varies from one food to another and even to those of the same type.
However, honey is a safer food than other processed foods in terms of HMF concentration.
Floral honey and manna honey treated at 95°C for 90 minutes and at 90°C for 75 minutes showed HMF levels below 40 mg/kg. In contrast to honey, when processing other foods, at relatively higher temperatures (during cooking, frying), longer times and different additives are required, which profoundly affects the HMF content in the food.
For example, cakes baked at temperatures above 200 °C accumulate 10 to 100 times more HMF (167.4 to 1,100.1 mg/kg) than cakes baked below 200 °C (9.9 to 39.6 mg/kg).
It has been reported that fresh cakes baked at 300 °C and added sugar during processing contain up to 1100 mg/kg HMF. Even the addition of ammonium bicarbonate can significantly increase the HMF content (more than 3500 mg/kg) in cakes containing sucrose, baked at 220 °C. Thus, the formation of HMF is unavoidable and the comparison or classification of foods with respect to HMF concentration cannot be performed accurately.
Health effects of HMF. Studies and conclusions.
Because we've expanded so much on the subject of hydroxymethylsulfural (HMF for short), let's take a look at its effects on us. Numerous studies have shown that HMF has negative effects on human health, such as mucosal, skin and upper respiratory cytotoxicity, mutagenic effects, chromosomal aberrations and oncogenicity in animals and humans, and enzyme inhibition. However, in more recent studies, HMF has been shown to have a range of positive effects, such as antioxidant, anti-allergic, anti-inflammatory, anti-hypoxic or a decrease in excess uric acid.
For example, oral administration to mice of 900 or 1300 mg/kg alone showed significant DNA damage to kidney cells. Preclinical and initiation studies have confirmed that 5-HMF causes chromosomal aberrations. Orally administered HMF is converted to reactive SMF (a metabolite of HMF) after absorption from the gastrointestinal tract which is not immediately excreted in the urine due to renal reabsorption, allowing SMF to accumulate in plasma and make it available to react with cellular proteins and DNA. In pre-clinical studies, HMF and its derivative SMF have been shown to be carcinogenic. At a daily oral dose of 500 mg/kg body weight, mice developed numerous intestinal adenomatous foci, but other researchers who performed the same experiment were unable to induce intestinal tumours with HMF.
Upon topical application of sulphoxymethyl (SMF) and chloromethyl derivatives of HMF, mice developed papillomas on their skin. Another HMF derivative, 5-chloromethylfurfural, induced hepatocellular carcinoma in male rats. However, we cannot fail to note that pure HMF was used daily at doses hundreds of times higher than the safe dose.
In contrast to these studies, a study by Zhao et al, indicated that HMF can induce DNA cell apoptosis, having anti-carcinogenic action.
HMF appears to have cytotoxic effects at high concentrations as the compound causes irritation of the mucous membranes, skin, eyes and upper respiratory tract. Its metabolite, SMF, was shown to be a potent nephrotoxic agent in an in vivo study in which male mice were given a huge dose of SMF (250 mg/kg) intraperitoneally. After 5-11 days after treatment, the mice died or became moribund, probably due to liver or more severe kidney damage. Another ex vivo study indicated that HMF lowered cellular glutathione (glutathione is a potent antioxidant produced in the liver).
However, there appear to be positive health effects. Some studies show the antioxidant effects of HMF, neutralising free radicals.
Some studies also show that HMF has a protective effect on hepatocytes damaged by hydrogen peroxide (H2O2). Other research
show that when administered in small amounts, HMF can increase survival under hypobaric hypoxic conditions and could be a potent therapeutic agent against acute mountain sickness, high altitude cerebral oedema and high altitude pulmonary oedema, significantly attenuating the degree of permeability. induced hypobaric hypoxia of the blood-brain barrier and the degree of neuronal injury in the CA1 region of the hippocampus. HMF also has an antiallergic effect by blocking histamine release and Ca2 + signalling by neutralising free radicals.
As can be seen, some studies have different and even opposite results. Of course, the results depend on the approach (human or animal cell studies carried out in the laboratory, in vivo studies in animals and humans), the oral administration, by injection, by infusion or by topical application, small, medium or large doses, and last but not least, the administration of a single compound, extracted from the "context", i.e. the food from which it comes.
The situation becomes even more complex when the particularities of the body exposed to large amounts of HMF are taken into account. Numerous studies have shown that different cells respond differently to HMF-induced cytotoxicity. The sensitivity of cells to HMF depends on the presence and expression levels of metabolic receptors, structure and enzyme activity.
At preclinical level, no toxic effects were observed at daily doses between 80 and 100 mg/kg body weight. This means that a 70 kg man would have to consume more than 150 kg of heat-treated honey to become ill, which is absurd. The 6-7 grams of honey in hot tea or a few dozen grams in a cake tin do not justify worrying about the so-called toxic effects of honey. And if we keep talking about honey cakes, a lot more HMF is produced from the flour or milk used to make them.
Zaitzev and colleagues set a safe daily dose of 132 mg/day for HMF using a 40-fold safety margin. What is more important to mention is that in humans, HMF and its metabolites are completely eliminated in the urine within 48 hours after oral administration of 240 mg /day (much higher than the dose considered safe).
As a component of processed foods, HMF has both adverse and beneficial effects on human and bee health. Some effects of HMF on human health and its carcinogenic and anti-carcinogenic properties remain inconclusive, with many studies being conducted only at pre-clinical level.
Beyond all this, at the individual level, we still have to use our common sense, but also not to neglect information that can be extremely useful to us. Heat-treated honey is certainly not the best option when you want to benefit from all its exceptional therapeutic properties, some of which we have already mentioned.
If we are looking for healing or regenerative effects, we will use unheated raw honey that we do not heat process.
If, for example, we drink herbal tea for a virus or cough, we would prefer to let the tea cool down before adding honey. This way we will take full advantage of the enzymes naturally present in honey, antimicrobial factors, antioxidants, anti-inflammatories and expectorants, and on the other hand we will not irritate the already inflamed throat with a very hot liquid.
If we want to use it as a sweetener for hot liquids or healthy sweets (not those with white flour, refined oil, margarine, pasteurised milk or powder, additives, colourings, etc. - which themselves have multiple harmful effects on health), we can do so without the aberrant fear that we will develop who knows what serious and threatening disease.
In addition, as mentioned above, it is good to have a varied, balanced diet, without excess, consisting of whole foods and as little processed food as possible and with a higher consumption of raw foods.
In this way we will have a lower intake of hydroxymethylsulfural, we will avoid many other more harmful substances, but above all we will provide an important intake of nutrients and substances with a protective role. This will help us to have a healthy and harmonious body and a healthy state.