Fat-soluble vitamins

Fat-soluble vitamins A, D, E and K are vitamins. Data on fat-soluble vitamins, except for vitamin E, and their relationship to physical activity are few. Recent evidence suggests that excess vitamin A can cause a decrease in the density of minerals in the bones and increase the risk of hip fractures. It is emphasized that megadoses of vitamin A also have a harmful effect on the body.

Despite the fact that vitamin A is well known as an antioxidant, beta-carotene is not an effective antioxidant, and can be a pro-oxidant. It has been shown that beta-carotene derivatives can be present in the lungs and arterial blood, possibly stimulating the growth of tumors, especially in smokers and those who inhale tobacco smoke and vehicle exhaust fumes. Therefore, people involved in sports, especially those living in cities where there are many cars, should not take beta-carotene supplements.

• Vitamin A

Vitamin A is a fat-soluble vitamin. It affects vision, participates in cell differentiation, reproductive processes, pregnancy, fetal development and bone tissue formation. RDN for vitamin A are given in the Annex.

Recommendations for physically active persons. Estimates of vitamin A intake in physically active individuals are very diverse, but some of them are erroneous, since they do not specify the source of the vitamin (vegetable or animal) origin. People who consume little fruit and vegetables usually have a lower level of vitamin A, unlike those who eat a lot of fruits and vegetables. Since vitamin A is fat-soluble and accumulates in the body, a mega dose of it is not recommended.

Vitamin A is also known as an antioxidant. For athletes, it can be ergogenic.

• Vitamin D

Vitamin D (calciferol) regulates the exchange of calcium and phosphorus in the body. Its importance is to maintain calcium homeostasis and bone structure. Vitamin D is synthesized in the human body by the action of sunlight from provitamin D3. The conversion of vitamin D into its more active forms begins first in the liver, then in the kidneys, where 1-alpha-hydroxylase adds a second hydroxyl group to the first position on 25-hydroxyvitamin D, which results in 1,25-dihydroxyvitamin D3 (1.25 - (OH) 2D3). The most active form of vitamin D is calcitriol. The effect of calcitriol on calcium metabolism is discussed in more detail in the "Calcium" section. The appendix contains standards for vitamin D.

Recommendations for physically active persons. Until now, studies on the effect of physical motor activity on the needs for vitamin D and its effect on the performance of the exercises were few. However, there is evidence that weightlifting can increase the levels of calcitriol and Gla-protein (bone formation) in the blood serum, resulting in improved bone adhesion. Bell et al. Reported changes in serum levels of calcitriol, but no changes in the levels of calcium, phosphate and magnesium were observed. Moreover, there are convincing data on the effects of 1,25-dihydroxyvitamin on muscle function; receptors 1,25-dihydroxyvitamin D3 were found in the culture of human muscle cells. However, the daily intake of 0.50 μg of 1,25-dihydroxyvitamin D3 for 6 months by men and women aged 69 years did not increase the strength of the muscles. However, as with other nutrients, it is necessary to check the vitamin D content of athletes who consume low-calorie foods, since long-term adverse effects on calcium homeostasis and bone mineral density can occur. Moreover, the need for vitamin D in the winter months can increase in people living at latitudes of 42 ° or more (for example, New England states), to prevent the increase in the secretion of parathyroid hormone and decrease the density of minerals in bone tissue.

Sources. Few foods contain vitamin D. The best food sources are vitamin-enriched milk, fatty fish and fortified cereal for breakfast. A daily 15-minute exposure to the sun also gives a sufficient amount of vitamin D.

• Vitamin E

Vitamin E belongs to a family of eight related compounds known as tocopherols and tocotrienols. Like vitamin A, its antioxidant effect is well known, which prevents damage to cell membranes by free radicals. The role of vitamin E in immune processes is also known. The needs for vitamin E are based on RDN and are given in the Appendix.

Recommendations for physically active persons. The effect of the load on the vitamin E requirements was estimated. Some scientists note a significant relationship between life-long motor activity and vitamin E levels in men living in Northern Ireland, others concluded that their physical activity causes a decrease in the level of vitamin E in the muscles, which is restored after 24 hours or more, as well as the redistribution of vitamin E between the liver and muscles, and vice versa, others argue that the usual or one-time load does not affect the concentration of vitamin E in individuals with different u ovnem fitness.

For additional assessments of the effect of physical exertion on vitamin E levels, a series of studies was carried out. Since the endurance load increases oxygen consumption, thus increasing the oxidant tension, it seems logical that the increase in vitamin E will be useful to physically active individuals. In addition, physical activity increases body temperature, catecholamine levels, production of lactic acid, increases temporary hypoxia and tissue reoxygenation, and all this contributes to the formation of free radicals. Moreover, one of the physiological responses to the load is an increase in the size and number of mitochondria, which are the site of production of reactive oxygen species. They also contain unsaturated lipids, iron and unpaired electrons, which makes them key to attacking free radicals. Vitamin E protects skeletal muscles from damage by free radicals, it can also have an ergogenic effect.

Many studies have determined the effect of exercise, vitamin E levels and supplements on skeletal muscle damage by oxidants, as well as the activity of antioxidant enzymes. A number of animal experiments indicate that vitamin E supplements reduce oxidative damage caused by stress; only a few studies were carried out with people. Reddy et al. Studied the effect of a single debilitating exercise in rats and found that the production of free radicals was greater in rats deficient in vitamin E and selenium than in rats that consumed supplements containing these vitamins. Vasankari et al. Studied the effects of additives 294 mg of vitamin E, 1000 mg of vitamin C and 60 mg of ubiquinone for endurance in eight male runners. It has been found that these supplements have increased the antioxidant potential and if vitamin E is added with other antioxidants, this gives a synergistic effect preventing the oxidation of low density lipoproteins. Other studies indicate a lower level of serum creatine kinase, a measure of muscle damage in marathoners who received supplements of vitamins E and C. McBride et al. Studied the effect of training and additional vitamin E on the formation of free radicals. Twelve men exercising in weight lifting were given 1200 IU of vitamin E supplements (alpha-tocopherol succinate) or placebo for 2 weeks. In both groups there was an increase in the activity of creatine kinase and the level of malonic dialdehyde before and after physical exertion, however, vitamin E reduced the growth of these values after the load, thus reducing damage to muscle membranes. In addition, vitamin E supplements appear to be not effective as an ergogenic aid. Although vitamin E reduces the amount of free radicals in the trainees, reducing the rupture of membranes, however, there is no evidence that vitamin E really increases these indices. Nevertheless, the role of vitamin E in the prevention of oxidative damage caused by physical exertion can be significant and further research to determine this effect is necessary.

• Vitamins of group K

Vitamins of group K are fat-soluble and heat-resistant. Phylloquinone, or phytonadonna (vitamin K,) is found in plants; menaquinone (vitamin K2) is produced by bacteria in the intestines, satisfying the daily requirement for vitamin K; Mepadion (vitamin K3) represents the synthetic form of vitamin K.

Alkalis, strong acids, radiation and oxidants can destroy vitamin K. Vitamin is absorbed from the upper surface of the small intestine with the help of bile or its salts, as well as pancreatic juice, and then transferred to the liver for the synthesis of prothrombin, a key factor in blood clotting.

Vitamin K is necessary for normal blood clotting, for the synthesis of prothrombin and other proteins (factors IX, VII and X) involved in blood coagulation. Vitamin K with the help of potassium and calcium is involved in the conversion of prothrombin into thrombin. Thrombin is an important factor in the conversion of fibrinogen into an active clot of fibrin. Kumarin acts as an anticoagulant, competing with vitamin K. Kumarin, or synthetic dicumarin, is used in medicine primarily as an oral anticoagulant to reduce the level of prothrombin. Salicylates, for example, aspirin, which is often taken by patients who have had myocardial infarction, increase the need for vitamin K. It is shown that vitamin K affects bone metabolism, facilitating the synthesis of osteocalcin (also known as bone protein). The bone contains proteins with the remains of gamma-carboxyglutamate, dependent on vitamin K. The deterioration of vitamin K metabolism is associated with inadequate carboxylation of the non-collagen bone protein of osteocalcin (containing gamma carboxyglutamate residues). If osteocalcin is not completely carboxylated, the normal formation of bone tissue deteriorates. Optimum consumption. RDN for vitamin K are given in the Appendix. The average diet usually provides at least a minimum of vitamin A, which is 75-150 μg per day, and a maximum of 300-700 μg per day. Absorption of vitamin K can vary in different people, but is estimated as 20-60% of total intake. Toxicity from vitamin K from natural sources is rare, it is more evident from synthetic sources of vitamin K, used in medicine. Vitamin K deficiency is more common than previously thought. Western diets with high sugar content and processed foods, megadoses of vitamins A and E, as well as antibiotics can help reduce the function of intestinal bacteria, which leads to a decrease in the production and / or decomposition of vitamin K.

Recommendations for physically active persons. Studies on vitamin K in connection with physical activity or ergogenic effect were not performed. Since vitamin K is not absorbed as efficiently as previously thought, its role in preventing bone loss has become more apparent, and this can provide an incentive for researching the role of vitamin K in athletes, especially women.

Sources. The best food sources of vitamin K are green leafy vegetables, liver, broccoli, peas and green beans.

[1], [2], [3], [4], [5], [6], [7]