Vitamin С. Requirements in Man Accumulated experience and the experiments recorded show that, in adult humans, 10 mg. of dietary ascorbic acid is completely protective anti curative over long periods. To allow a margin of safety a daily intake of 30 mg is recomended.
This is readily,achieved by a normal Western diet —one orange, or half a grapefruit, or a generous helping of lightly-cooked cabbage. The recommended 30 pig. Is of ingested vitamin, so that the aim of 70 mg. makes liberal allowance for maltreatment by the cook.
Vitamin B group. This group consists of series of water-soluble organic substances, which are found in all cells of all species, froifi the bacteria, protozoa, and yeasts up to the highest mammalian forms. Most of the members of the group are constituents of fundamental tissue enzyme systems, involved in the oxidation of the foodstuffs, and are therefore indispensable for the normal functioning of all tissues. The best studied members of the group are ttiiamine, riboflavin, and nicotinic acid, generally found together in foodstuffs but not necessarily in the same, proportions. Most of the vitamin В group can be synthesized by the intestinal bacteria.
Vitamin K. Vitamin K discovered only some 30 years ago, is of great importance for the proper coagulation of blood. It is essential for the formation of
prothrombin, a proteic substance necessary for clotting a blood vessel to stop a
haemorage.
In 1942, Academician Alexander Palladin, a prominent Soviet biochemist, and his staff synthesized vikasol, a new Soviet preparation, which contains an analogue of vitamin K. During World War II, vikasol won a good repute for itself, among army doctors. Injected intramuscularly or intravenously, it quickly stops various haemor-rhages.
Now Soviet researchers have found a new appiicatiw for vikasol — it is used
as a preparation against inflammations and as a means for increasing the resistance of organism to radioactive irradiatipn.
But vitamin K, as the scientists learned, is essential not only for blood clotting. It plays an active role in the so-called tissue breathing of the organism's cells, in the metabolism.. It is as necessary for each living cell as air is vital for man. -
Sugars and starches. Sugars, and starches are important sources of energy in
your.food. They are present in candies, cakes, potatoes, bread and many other common foods. Most of the starch and sugar you eat is changed to simple sugars like glucose in your digestive system. When they travel through the blood stream, some of the sugars are stored, but others will be burned in the cells to produ- produce the energy we need for life. It is possible to measure the amount of energy produced by a food by burning it outside the body. The heat given off is measured very carefully. The unit of heat energy in food is called a calo- Fats. They, give much, more energy than do stafch or sugar. (You -can easily burn fatty foods peanuts or walnuts by lighting them with a match.) Fats do not burn this way in your body cells, but they are used to produce heat and energy. Fats do more than simply supply calories.
They are necessary for the continued health of the cells, are unable to grow on a fat-free diet. Children who have no fat in their diet do not properly either and were very weak and underdeveloped.
They supply energy but that is not their chief use in the body. Every time a new cell forms, protein is needed to shake up its protoplasm. Life would be impossible without proteins since protoplasm is made of them.
Minerals. There зге several different minerals needed for beatth. AH of them
come from our food and water. They are calcium and phosphorus, flourine, iron, iodine ana many others.
XII. Reproduce in your own words:
Витамины — пищевые вещества, необходимые для поддержания жизненных функций. Организм человека и животных не синтезирует витамины, поэтому получать их должен в готовом виде. Недостаток витаминов в пище или изменение процессов их усвоений приводит к нарушениям обмена веществ.
Витамины должны поступать в организм постоянно в относительно определенных количествах. Однако содержание эитамйнов в пищевых продуктах подвержено значительным колебаниям и не всегда полностью обеспечивает потребность в них организма. Эти колебания связаны с изменениями состава пищевых продуктов, неравномерным употреблением ягод, фруктов, овощей.
Открытие витаминов тесно связано с изучением роли отдельных пищевых веществ. Во второй половине XIX в. считалось, что для нормального функционирований организма достаточно определенного содержания в пище белков, жиров, углеводов и минеральных солей и воды.
Однако в течение долгого времени ученым не удавалось установить причину происхождения многих заболеваний. В 1880 г. русский исследователь Н. И. Лунин установил, что в пищевых продуктах имеются еще неизвестные факторы питания, необходимые для жизни. Выводы Лунина были в дальнейшем подтверждены С. А. Сосиным,а в 1897 г.— врачом Эйкманом. В 1906—1912 годах по предложению Гопкинса и польского ученого Функа эти вещества были названы витаминами.
XIII. Questions for discussion:
1. What are nutrients? Give examples.
2. What is the chief use of sugar and starch in the body?
3. What are the good food sources of sugar and starch?
4. What is meant by a calorie?
5. What nutrient gives the most energy?
6. What is the chief use of protein in the body?
7. What are some good food sources of proteins?
