Smoking with your stomach

This column is written by Stig Bengmark – Professor Emeritus, scientist, lecturer and writer. Read more of Stig Bengmark’s columns here.

A.G.E. and A.L.E. – the health terrorists of today

In chemistry lessons at school, all children learn that heating things leads to synthetic processes and creates possibilities for new substances to be formed by two or more substances merging – a possibility which today’s food industry and all households that heat their food are engaging with diligently. When foods are exposed to temperatures above 80-100°, they have completely different properties than the original substances and become toxic, albeit mildly, and contribute to chronic inflammation as well as the onset of chronic diseases.

What most often takes place with heating up of food is that a protein merges with a sugar. This is called glycation, and its products are advanced glycation products (A.G.E.). It’s almost as common for a protein to merge with a fat, which is then called lipoxidation, and its products are called advanced lipoxidation products (A.L.E.). This column is about these products and their impact on our health.

Heating food was being questioned long ago, but the first person to seriously question it was the French researcher, Louis Camille Maillard (1878 – 1936). Maillard researched the substance, urea, formed by the release of ammonia during the breakdown of proteins in the body and which is excreted via the urine. Maillard pointed out that high levels of urea could lead to impaired kidney function, something he called urogenic imperfection, and cause chronic kidney disease. He created what he called the index of urogenic imperfection, an index that proved useful in clinical medicine for many years. Maillard’s scientific contribution was much appreciated in scientific circles and he was awarded the French Academy’s grand prize, but not long after that, it seemed everything was done to forget about it – Maillard’s observation was certainly not something that suited French food culture.


Thanks to today’s molecular biology and refined methods of reading how the cells in the body feel, however, it has been shown that Maillard was right – eating A.G.E. and A.L.E. in larger quantities is really like ‘smoking with your stomach’. A.G.E. and A.L.E. contribute greatly towards increased inflammation in the body and thus also to the onset of chronic diseases – not just chronic kidney disease as Maillard suggested, but, to a greater or lesser extent, to all chronic diseases.

In modern times, several A.G.E.’s and A.L.E.’s have been identified, but new ones are being added every year. Today we know of hundreds of different A.G.E.’s and A.L.E.’s, and the best-known among the public is acrylamide – the substance that led to the construction of the tunnel through Hallandsåsen coming to a standstill for several years. The synthesis of acrylamide speeds up at 120-130° and the figure below shows the content of acrylamide in potato chips when heated to over 200°.

Toasting bread also adds significant amounts of acrylamide, often 10 to 20 times more than when it’s untoasted. Unfortunately, I have no access to knowledge of what heating at 300° brings – the temperature at which the majority of commercial breads are made (even gluten-free).

Unfortunately, clinical medicine does not routinely measure the levels of these substances in the body, with the exception of patients with diabetes and in some cases also Alzheimer’s and certain eye diseases. They measure the level of glycosylated (or glycated) and haemoglobin (HbA1c) in the blood, which gives a good picture of how the blood sugar has been behaving in recent months and shows the patient’s future prospects, at least according to some researchers. Research on these substances and their effects on health has made great strides in the last two to three decades. There are now approximately 40,000 scientific publications on these substances, of which just over 30,000 are on HbA1c. And as a result, many diseases, especially chronic ones, have been associated with high levels of A.G.E. and A.L.E. – not alone, but in combination with several other inflammation-causing factors.

A.G.E. and A.L.E. are also formed in the microwave

Fresh tobacco leaves, fresh coffee beans and fresh peanuts are not often rich in antioxidant substances, as they unfortunately disappear during industrial treatment with strong heating, and are replaced by less healthy A.G.E./A.L.E. complexes. Most known plant antioxidants are rendered inactive at temperatures between 30° and 100°. The antioxidants in olive and rapeseed oil, for example, begin to be eliminated as low as at about 30°, and stronger heating, such as in microwaves, eliminates almost all antioxidants. As the antioxidants disappear, the Maillard products accelerate, which continues at an almost exponential rate. A.G.E. and A.L.E. are also formed by radiation, ionisation and microwave treatment but also, and this is important, by long-term storage at room temperature. When the temperature is raised from 100–120°, carcinogenic substances, especially of the heterocyclic amine type, are formed in increasing amounts.

Also watch out for foods that contain milk powder

The goodwill of politicians has made wheat and dairy products extremely cheap through enormous agricultural subsidies, which is one of the reasons why these are used in a lot of commercial foods where, in my opinion, they don’t really belong. The excess milk is converted into powdered milk which is particularly rich in A.G.E. and A.L.E. – especially the A.G.E. substance furosine – and especially if it’s stored at room temperature for a long time.

Unfortunately, the infant formulas as well as clinical nutritional solutions of today are largely based on powdered milk – something that’s both inexplicable and unacceptable given today’s knowledge. My advice is not to use these alternatives – the first year of life is especially sensitive as it’s at this time that the immune system is being calibrated and fine-tuned. Instead, start earlier with mashed soft vegetables and fruits such as banana and avocado – just as we’ve done for millennia. That’s what my mother did many years ago and it’s still giving me health benefits today!

So what can conclusions can we draw from this?

Ideally, no food should ever be heated above 80°. Of course, it’s best to avoid stronger ways of heating food as much as possible, but if you want to heat your food for some reason, boiling it, especially steaming, is preferable. Your microwave should be used with great care – perhaps mostly to gently heat up water and, if necessary, food. If you want to use an oven, you should aim to use temperatures below 100°. This is always an option for poultry, meat, and fish. For hygienic reasons, poultry has to be heated to an internal temperature of at least 65°, meat only needs a final internal temperature of between 49° (roast beef) and 65° (well done) and fish between 44° (‘transparent’) and 65° (well done). Therefore, animal-based food can always be prepared in the oven at a temperature well below 100° – meat and fish at an oven temperature of about 70° and poultry 75-80° (this requires several hours in the oven). The big problem is undoubtedly bread, which unfortunately requires an internal temperature of 92–95°, which requires an oven temperature of at least 110 °. The alternative is to sprout the grain and eat it as some kind of muesli or to bake crispbread/biscuits at a temperature of 50-60 °, which we often prefer to do. However, it’s always by far the best to eat the grains as they are, raw and preferably sprouted.

I hereby challenge all skilled, health-conscious bakers and chefs to help develop new methods of preparing food, and especially to bake alternative breads, preferably from new antioxidant-rich grains such as sorghum/durra and teff. When I was a child, we baked bread with steam and the Chinese are still doing so today.

Literature and references

Bengmark S. Our modern diet is the cause of inflammation and disease development. Heating food produces dysfunctional proteins that accumulate in the body. Läkartidningen 2007;51:3873-3877

Bengmark S. Advanced glycation and lipoxidation end products – amplifiers of inflammation: the role of food. JPEN 2007;31:430-440

Bengmark S AGE, ALE RAGE and disease – a foods perspective. In Handbook of Prebiotics and Probiotics Ingredients: Health Benefits and Food Applications Edited by Susan S Cho, Terry Finocchiaro CRC Press, Taylor and Francis Group, Boca Raton 2009

Bengmark S. Modified Amino Acid-Based Molecules; Accumulation and Health Implications. In Amino Acids in Human Nutrition and Health. Ed Mello JFD, CABI Allingfo



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