Vitamin E: Protection for the cells
When it was discovered, it was assumed that vitamin E was important for the fertility of mammals. This is how it got its scientific name: tocopherol. This is derived from the ancient Greek words "tocos", which can be translated as "birth", and "pherein", which means nothing other than "to bring". Tocopherol was therefore supposed to bring about birth. It is now assumed that vitamin E mainly protects cells from oxidation, i.e. from damage caused by certain metabolic processes. It has also been shown that it is not a single substance, but a whole group of fat-soluble substances with similar properties. Find out everything you need to know about tocopherols here.
Vegetable oils contain a lot of vitamin E.
How and when was vitamin E discovered?
Vitamin E was discovered in 1922 by a research group led by Herbert M. Evans and Katherine S. Bishop. Evans, a professor of anatomy, had already been studying embryonic development during his time as a student. In a series of studies, he was able to demonstrate the influence of food on the sexual cycle of rats. If certain food components were missing, the test animals became infertile. By using different diets, the determining factor was finally isolated from wheat germ oil and corn and assigned to the group of vitamins that had only just been discovered at the time. In 1937, the antioxidant effect of tocopherol was also discovered for the first time. The following year, the chemical structure of vitamin E was finally described by Erhard Fernholtz. Paul Karrer then succeeded in synthesizing it. He also deciphered the structure of vitamins A and B and was awarded the Nobel Prize in Chemistry for his research.
The chemical structure of vitamin E
As mentioned before, vitamin E is a group of substances with similar properties. The chemical structure of the individual substances is also similar. Now it will be a little technical: the chemical structure they all have in common is a so-called chroman ring as a base. They also have an "attached side chain". This is not jewelry, but also a chemical structure that can be saturated or unsaturated. You are probably more familiar with this from fatty acids. If the side chain is saturated, it is a tocopherol; if the side chain is monounsaturated, it is a tocomonoenol; and if the side chain has three double bonds, it is a tocotrienol. Four different degrees of methylation are also possible for the chroman ring. These are referred to as α, β, γ and δ. To make things a little more complicated, three of the four methyl groups in the side chain can also occupy different spatial positions. They can be aligned to the right (R) or to the left (S). Tocopherols only occur naturally in the (RRR) configuration. The highest biological activity is found in α-tocopherol. This is also the best-researched form of vitamin E. Phew – that was enough chemistry for today!
Chemical structure of vitamin E (alpha-tocopherol).
What is the biological significance of vitamin E?
The main function of vitamin E is to protect cells from oxidation by free radicals , i.e. particularly aggressive oxygen compounds that can damage cells. Tocopherols can be found in all cell walls and in particular protect the polyunsaturated fatty acids they contain from oxidation. Vitamin E itself becomes a radical in the process, albeit an inert one and therefore harmless. Ascorbic acid, i.e. vitamin C, can regenerate this radical back into vitamin E. Vitamin E also appears to be involved in the control of the gonads, i.e. the ovaries in women and the testicles in men. The name, derived from ancient Greek, is therefore not entirely wrong. (RRR)-α-tocopherol has the highest biological activity. It is transported into the blood plasma better than other tocopherols by a special protein that is produced in the liver.
Current research on vitamin E
In the past, the various tocopherols and tocotrienols were largely equated with α-tocopherol. Differences were mainly seen in bioavailability. Research currently assumes that δ-tocopherol only has ten percent of the biological activity of α-tocopherol. For this reason, studies on the effectiveness of vitamin E were mainly carried out with α-tocopherol in the past. However, more recent studies indicate that the different forms could also be involved in different physiological processes. γ-tocopherol seems to capture not only oxygen radicals, but also nitrogen radicals - which would give it even greater anti-inflammatory potential. There is also evidence that tocopherol could also be involved as a signaling molecule in the activation of immune cells. It is assumed that α-tocopherol inhibits the release of leukocytes, while γ- and δ-tocopherol have the opposite effect. There are also no meaningful studies on the interactions between tocopherols. Exciting findings are expected in the future.
How is vitamin E produced and how is it absorbed?
Only plants and some cyanobacteria are capable of biosynthesizing vitamin E. Animal products therefore only contain small amounts at most. Good sources of the fat-soluble vitamin are vegetable oils, oilseeds and nuts. With an impressive 215 mg per 100 g, wheat germ oil has the highest vitamin E content. In addition to α-tocopherol, wheat germ oil also contains β-tocopherol. Soybean oil, on the other hand, also contains γ- and δ-tocopherol. In order to ensure a supply of all vitamers, you should therefore ensure that your diet is varied. If you repeatedly use different whole grain products and do not always use the same cooking oil, you should be on the safe side. Vitamin E from dietary supplements should always be taken with a little oil or at least a slightly fatty meal. This is because the transfer through the intestinal wall takes place in so-called micelles. These are, by and large, nothing more than tiny fat droplets.
What happens if you have a vitamin E deficiency?
The German Nutrition Society recommends that adult women consume 11-12 mg of vitamin E daily. The daily requirement for men is therefore 12-15 mg. Since the body can store the fat-soluble vitamin very well, deficiency diseases are extremely rare and are usually associated with pathologically impaired nutrient absorption. This can be the case, for example, with chronic inflammatory bowel disease, anorexia or impaired fat digestion. The signs of a vitamin deficiency can be very diverse and are mainly manifested by impaired muscle and nerve function. Circulatory problems, a general weakened immune system, involuntary tremors and slow reflexes are also possible. In addition, long-term vitamin E deficiency can cause damage to the retina.
Nuts are also a good source of vitamin E.
Is it possible to overdose on vitamin E?
For a long time, the intake of vitamin E was considered completely harmless. However, recent studies indicate that undesirable interactions can occur if the intake of vitamin E is too high. This particularly affects people with blood clotting disorders, as vitamin E interacts with vitamin K. This can further reduce the ability of the blood to clot. In men over 55, a daily dose of 268 mg or more has also been found to be at an increased risk of prostate cancer. The European Food Safety Authority (EFSA) has set a tolerable maximum amount of 300 mg for adults. In order not to exceed this value, the Federal Institute for Risk Assessment (BfR) recommends a value of 30 mg per day for food supplements.
