The negative effects of trans fats (also known as trans fatty acids, TFA) on our cardiovascular health have been known for a long time, they are among the most unhealthy food components of all.

In recent years, there has been an increase in the number of studies that prove an association between trans fat and  AD, as already reported by AMM in 2015 (https://spitzen-praevention.com/2015/08/14/transfettsaeuren-und-kognitive-schwaechen-da-fehlen-einem-die-worte/). 1,628 healthy Japanese seniors were followed by a current study from Japan over a period of 10 years. In this context, the researchers examined TFA elaidic acid in the blood as a marker substance, which allows direct conclusions about the total TFA intake. 377 participants developed dementia, of which 247 developed Alzheimer’s and 102 vascular dementia.  Higher serum elaidic acid levels were significantly associated with a greater risk of developing Alzheimer’s disease, vascular dementia and total dementia. Patients whose blood trans fatty acid levels were in the higher range were 90% more likely to develop Alzheimer’s disease. These relationships remained significant even after adjustment for nutritional factors, including total energy intake and the intake of saturated and polyunsaturated fatty acids.

Current situation in Germany

In the Japanese study, the TFA was consumed with sweet baked goods, crackers, ice cream and such, but what is the current exposure situation in Germany?

TFA can get into food in different ways:

  •  produced by bacterias in the rumen of ruminants (such as cows, sheep and goats) and thus enter muscle meat and milk. A health-promoting effect is even being discussed concerning these ruminant TFA.
  • industrially produced when processing vegetable oils, the so-called partial hydrogenating process. These TFA have been used extensively in industrial food production.
  • while frying and deep-frying processes, whereby the TSF are almost completely transferred from the fat into the fried food.

In 2016, the EU Commission published a draft law to limit trans fats in foods, according to which the content of industrial TSAs is to be limited to 2% in the total fat from 2021. National regulations exist only in individual member states (e.g. Denmark, Finland) and in Switzerland. The WHO has also launched a global initiative with the ‘REPLACE’ programme, which aims to eliminate it (to 1% of total calories) worldwide by 2023.

The good news is that although there is still no mandatory national regulation in Germany, fortunately, industrial TFA are virtually no longer used in pre-packaged foods. They have been almost completely replaced by palm oil or palm kernel oil, which is at least better for health, but unfortunately causes different kinds of problems. Problems with regard to TFA contents of more than 2% in total fat are posed by unpackaged, bulk or industrially-like prepared foods sold in snack bars and bakery chains, as no list of ingredients is required by law, and single cases with extremely high TFA contents are still being identified.

Risk of TFA formation by radicals in the body

Biological membranes, which occur in every cell of the body, consist of a double layer of phospholipids. They contain a high proportion of fatty acids, whereby their content of unsaturated (non-trans) fatty acids positively influences the properties of these cell membranes. Therefore, the formation of TFA in the membranes poses an apparently great danger: As soon as the fatty acids within the membranes are converted to the trans configuration and thus, TFA are generated, this can have a negative effect on the fluidity of the membrane and promote the development of chronic diseases.

A few years ago, a study showed that rats fed TFA-free food for lifetime had implemented trans-isomers of mono- and polyunsaturated fatty acids (oleic, linoleic, linolenic and arachidonic acid) in liver, kidneys, heart, adipose tissue and erythrocytes. Thus, it was proven that TFAs can be formed in the organism even if the food does not contain any TFAs. Subsequent studies have also shown that free radicals are responsible for the formation of TFAs in the body. Free radicals can be produced in the organism during essential metabolic processes under physiological conditions, but also by external influences such as cigarette smoke, air pollution, organic solvents or irradiation. Due to their high chemical reactivity, these free radicals can cause oxidative damage to cellular macromolecules. In addition, the increased occurrence of TFAs formed in the body, especially of trans arachidonic acid, has been observed due to accumulated radical stress in various pathological states, such as inflammation, diabetes and Alzheimer’s disease.

This became very obvious when a study using an Alzheimer’s animal model revealed that TFAs were found only in the brain and hippocampus of mice carrying a gene specific for Alzheimer’s disease, but not in healthy animals. This result suggests that stress due to amyloid β-mediated radicals that accumulated during the development of Alzheimer’s disease causes cis-trans isomerisation of fatty acids in neurons of Alzheimer’s mice. In a subsequent study, it was further shown that the animals had significantly reduced levels of TFA in the brain and hippocampus after administration of two antioxidant substances for 3 months. These studies thus imply that the administration of antioxidant substances may be a possible strategy to prevent the body’s own formation of TFA during the development of chronic diseases such as Alzheimer’s disease. Based on the results of all intervention studies, a variety of antioxidant vitamins and polyphenolic compounds derived from plants, including curcumin and resveratrol, appear to inhibit TFA formation in the body (Figure 1, modified after Hung et al. 2016).

Inhibition Trans Fatty Acids
Figure 1: Potential Inhibition of the Formation of Trans Fatty Acids in Human Membranes by Dietary Antioxidants

Conclusion:
The connection between Alzheimer’s disease and the consumption of trans-fatty acids (TFA) is becoming increasingly evident, although the exposure to TFA through pre-packaged food to TFA in Germany has decreased in recent years. The industry has reacted to the EU’s legal regulation, which will come into force in 2021, of a maximum of 2% of total fat. However, when you visit the snack bar and the bakery chain, remember that trans fats may still play a not inconsiderable role here.

However, the real danger of TFA seems to be in the body, as they can be produced there by free radicals. But you can do something about it with a healthy diet: Ensure your supply of antioxidant micronutrients from food and, if necessary, supplements, before the TFA otherwise formed in your body damage your cell membranes and drive you insane!

References:

  1. Honda,T et al (2019) Serum elaidic acid concentration and risk of dementia: The Hisayama Study. Neurology, 2019
  2. Informationsblatt der Europäischen Union 2019
  3. Bähr M, Jahreis G, Kuhnt K (2011) Trans fatty acids in foods on the German market and in human tissue. Ernährungsumschau 9
  4. Ghebreyesus T, Frieden TR (2018) REPLACE: a roadmap to make the world trans fat free by 2023. The Lancet 391
  5. Messdaten zu Trans-Fettsäuren aus der amtlichen Überwachung zu insgesamt 2.633 Proben aus den Jahren 2014-2017, Auskunft des Bundesamts für Verbraucherschutz und Lebensmittelsicherheit (BVL) vom 31. März 2017
  6. Kuhnt K, Degen C, Jahreis G (2015) Evaluation of the Impact of Ruminant trans Fatty Acids on Human Health: Important Aspects to Consider. Crit Rev Food Sci Nutr. 56
  7. Hung, WL et al (2016) Endogenous formation of trans fatty acids: Health implications and potential dietary intervention, Journal of Functional Foods 25

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