Vitamin E – Basic Knowhow About This Crucial Vitamin

Vitamin E  as a nutrient is one of the most powerful lipophilic antioxidants known where it scavenges free radicals and the waste products of oxygen metabolism. It is fat soluble and stops polyunsaturated fats and other vitamins like vitamin A, C and the B types from oxidation and so being destroyed. It has both important biological functions in both plant and animal cells as well as being part of the armoury of antioxidation in foods, cosmetics and a host of other consumer products.

It has been extremely well researched over the years! Just read articles by Yamauchi (1997).

Chemical Structure

Vitamin E is also known a collective name for the tocopherols (THs). The molecular structure of THs (i.e., α-, β-, γ- and δ-) consists of a chromanol ring connected to a long phytyl side chain at position 2 of the chromanol ring. Variations in the number and position of the methyl groups on the aromatic ring result in different THs.

What does that mean for us? It protects cell membranes which means they live longer and it is an exceptional antioxidant for protecting food from free radical damage.

Source

Vitamin E is found in many food types especially nuts and seeds, wheat germ which is in cereals and wholemeal bread, soya, olive oil and corn. A balanced daily diet provides all of our vitamin E and what isn’t used is stored unlike vitamin C.

• • Plant oils (sunflower, safflower, olive oil)
  • Nuts and seeds (almonds, sunflower seeds)
  • Green leafy vegetables (spinach, kale)
  • Fortified foods like cereals

Men need 4mg per day and women 3mg per day.  It is not known whether overdosing is an issue but as with all supplements follow the recommended intakes on the packs.

Role As An Antioxidant

Vitamin E is a powerful antioxidant that plays a crucial role in protecting cells from oxidative stress by neutralizing free radicals — unstable molecules that can damage cells.

1. Forms of Vitamin E
   • Vitamin E refers to a group of fat-soluble compounds, mainly tocopherols and tocotrienols.
   • Alpha-tocopherol is the most biologically active form and the one most commonly found in food and supplements. In vivo, the order of potency is α > γ whilst in in foods it is the other way round.
2. Antioxidant Action:
   • Free radicals are produced naturally in the body during metabolism or through external sources like UV rays and pollution in foods.
   • Vitamin E donates an electron to free radicals, stabilizing them and preventing them from attacking cell membranes, proteins, and DNA.
   • Tocopherol isomers act as chain-breaking antioxidants where they scavenge free radical especially those formed from unsaturated lipids (Kamal-Eldin & Appelqvist, 1996). The THs are very effective at this by donating their phenolic hydrogen atoms to pick off lipid peroxyl radicals (LOO•). This reduces the number of propagating reactions with mainly unsaturated fatty acids
   • The reaction between tocopherol and peroxyl radicals begins with the creation of a tocopheroxyl radical (T•) that reacts further with (LOO•). Non-radical products (NRP) are formed that bring the chain reaction to a close.
   • In food, γ-tocopherol is a more effective antioxidant than the alpha-form. In certain tests involving methyl linoleate ( a standard test material), the order of reaction is  α > β >γ >δ. (Mukai et al., 1986).
   • Inconsistencies are part explained by the concentration of the relative amounts of α – and γ-forms. At low antioxidant concentrations, the alpha-form is the most effective but as the concentration of TH rises, then the gamma-form becomes the most effective. If the initial concentration of THs is higher than 2 x 10E-3 then the gamma-form is the more effective Olcott & Van de Veen, 1968; Mukai et al., 2005). Tavadyan et al., (2023) recently unpicked the differences in behaviour using methyl linoleate peroxidation.
   • When α-tocopherol is heated with methyl linoleate in air it forms a variety of dimers, trimers, a quinone and other degradation products. The main products were the dimer and trimer when heated at 60C after prolonged heating. When heated at 100C, all the products are generally degradation ones and the dimers/trimers have disappeared. Finally, carbon dioxide and methanol are formed (Csallany et al., 1970).
3. Food Preservation:

1. 1. In food, vitamin E helps delay rancidity by preventing the oxidation of lipids (fats and oils).
   2. This extends shelf life, especially in products rich in unsaturated fats like vegetable oils, nuts, and seeds.
   3. It’s sometimes added to processed foods as a natural antioxidant (often listed as tocopherol on labels).

Synergy with Other Nutrients

• • Vitamin E works best with vitamin C since vitamin C helps regenerate vitamin E back to its active form after neutralizing free radicals.
  • It also interacts with selenium and zinc to bolster antioxidant defenses.

Stability

• • Vitamin E is relatively heat-stable but can degrade when exposed to light, air, and heat for prolonged periods.
  • Storing oils and nuts in dark, cool places preserves their vitamin E content.

References

Csallany, A. S., Chiu, M., & Draper, H. H. (1970). Oxidation products of α‐tocopherol formed in autoxidizing methyl linoleate. Lipids, 5(1), pp. 63-70.

Kamal-Eldin, A. and Appelqvist, L.-A. (1996). The chemistry and antioxidant properties of tocopherols and tocotrienols. Lipids, 31, pp.671 -701

Tavadyan, L., Martoyan, S., Kocharyan, G., Kamal-Eldin, A. (2023) Kinetic modeling of the reversal of antioxidant potency of α-, β-,γ- and δ-tocopherols in methyl linoleate peroxidation. Food Chemistry 406 134866

Yamauchi, R. (1997). Vitamin E: mechanism of its antioxidant activity. Food Science and Technology International, Tokyo, 3(4), pp. 301-309

Yamauchi, R., Miyake, N., Kato, K., & Ueno, Y. (1993). Reaction of α‐tocopherol with alkyl and alkylperoxyl radicals of methyl linoleate. Lipids, 28(3), pp. 201-206