Vitamin E levels
The term vitamin E encompasses 8 compounds, four tocopherols, and 4 tocotrienols, which occur naturally in foods of plant origin. Tocopherol is the main and most abundant form of vitamin E and can be alpha-tocopherol, beta-tocopherol, gamma-tocopherol, and delta-tocopherol. The gamma-tocopherol form is the most consumed among American populations, while the alpha-tocopherol form is the most consumed among Europeans.
Vitamin E is insoluble in water. On the contrary, it is fat-soluble, like vitamins A, D, and K. For this reason, the absorption of vitamin E depends on the absorption of lipids in the intestine, requiring pancreatic and biliary secretions. Once bound to the epithelial cells of the intestine, vitamin E is incorporated into chylomicrons, being secreted into the systemic circulation.
Vitamin E deficiency is usually secondary to disorders that hinder the absorption of vitamin E from fats, such as liver disorders, disorders of fat metabolism, and disorders of biliary secretion.
Vitamin E deficiency due to low dietary intake is rare in developed countries.
Among the most common causes that can lead to vitamin E deficiency is impaired absorption of fatty acids involved in vitamin E metabolism, mutations in the tocopherol transfer protein, patients with cystic fibrosis (a lung disorder that can also affect biliary secretion), patients with intestinal and/or liver syndromes or diseases such as cholestasis or primary biliary cirrhosis, and those with some inherited monogenic diseases directly or indirectly related to vitamin E, such as abetalipoproteinemia (a digestive disorder characterized by malabsorption of fats).
Role of genetics
There are different genes related to vitamin E levels and evaluated by our genetic experts, including CD36 (rs1761667 polymorphism), SCARB1 (rs11057830 and re5888 polymorphisms), TTPA (rs6994076 polymorphism), CYP4F2 (rs2108622 polymorphism), and ZPR1 (rs964184 polymorphism), all of them involved in the different processes of vitamin E metabolization and utilization.
Prevention of vitamin E deficiency
Nuts, seeds, and vegetable oils are among the best sources of alpha-tocopherol, and green leafy vegetables and fortified cereals contain significant amounts. Most of the vitamin E in American diets is in the form of gamma-tocopherol from soybean, canola, corn, and other vegetable oils.
Supplementation of non-dietary vitamin E is only suitable for those with nutritional deficiencies, as the consumption of high amounts of vitamin E can cause metabolic and cellular changes in humans, if the threshold value is exceeded, and can be a risk factor for mortality.
Gene or region studied