According to the National Health and Nutritional Examination Survey, 40 percent of the population is consuming too much or not enough nutrition. Although the intake of protein, iron and vitamins B1 and C is adequate, the average intake of calcium was 84 percent of the recommended amount, whereas the average intake of vitamin A was only 68 percent of the recommendation. Therefore, it is suggested that people consume more dairy products such as milk and cheese, small boned fish, yellow and green vegetables, and egg yolk, all which are rich in calcium and vitamin A.
A vitamin is an organic chemical compound existing in small amounts in natural food products. It is a nutrient needed for the normal metabolism of living organisms. Since many vitamins are not produced in the body, we must consume vitamins through our diet. Deficiency of vitamins can lead to various syndromes and even death.
Vitamins B and C are soluble vitamins, which means that they do not accumulate in the body even if too much is consumed. In general, soluble vitamins are involved in tissues that are actively metabolizing or growing, skin, blood, and gastrointestinal and nervous systems. Deficiency of these vitamins can lead to dermatitis, anemia, decreased digestive function and neurological problems.
Deficiency of a single type of vitamin B can lead to problems with basic cell biology. Vitamin B1 is found in cereals, meats, legumes, nuts and fish. A vitamin B1 deficiency can lead to beriberi. Its symptoms include decreased appetite, general fatigue, insomnia, tiredness and edema, which can progress to sensory and motor problems. It is caused by the consumption of only purely white rice, alcoholism, decreased digestive absorption, use of diuretics, liver disease and diabetes. The recommended intake of vitamin B1 in adults is 1.3 mg for men and 1.0 mg for women.
The main sources of vitamin B2 are milk, cheese, eggs, soy sauce and meals. Vitamin B2 is destroyed by UV light. A vitamin B2 deficiency can lead to angular stomatitis, glossitis, and seborrheic dermatitis. The daily recommended intake is 1.5 mg for men and 1.2 mg for women.
The biological function of vitamin C is not understood completely. Some say that it helps overcome fatigue and the common cold. Some studies have shown that it can reduce blood pressure but to a very small extent, so it cannot be used as an alternative for blood pressure tablets (antihypertensives).
The vitamin that has attracted much attention in the past decade is folate. Folate is has been added to all cereal foods in the U.S. and Canada since 1998. Folate plays an important role in the production of neurons. It is particularly important in the first month of pregnancy, as this is the time when the nervous system and the spinal nerves are formed in the fetus. Folate deficiency in this time of gestation can lead to malformation of the brain. There is an increased risk of spina bifida, or hydrocephalus where cerebrospinal fluid collects in one part of the brain. This is permanent damage, so legislation has been passed to add it to staple foods for the public. According to research, approximately 40 percent of the American population has a folate deficiency. Folate is unstable in heat and storage and is lost during cooking, which means that its intake is significantly reduced through diet. Folate supplemented cereals for breakfast can heal to increase folate intake. Foods rich in folate include spinach, dark green vegetables, beans, oranges, yeast, egg yellow, fish and liver. However, most folate is destroyed during cooking. Therefore folate supplements are beneficial for women in their reproductive age, patients with hypertension, cardiovascular disease and peripheral vascular disease, memory loss, alcohol abuse and elderly patients with poor diets.
Lipid-soluble vitamins are absorbed through the diet, like fatty acids, and are stored in the liver or fat tissues. They are not excreted in the urine, and are stored in storage tissues. Therefore, an overdose of these vitamins can lead to toxicity, so supplementation should be done carefully. Vitamin A (retinol) should not be taken at a dose of 3,000 RE (retinol equivalents), which is triple the recommended intake for men, without a doctor’s prescription. Children who consume adult vitamins for a long period of time can accumulate vitamin A that in turn causes brain and liver injuries. It is therefore important to check the doses of these vitamins when using multivitamin tablets.
Additionally in recent years, intake of 800 units of vitamin D is recommended for the elderly to prevent injury from falls and osteoporosis.
By Yoo Jun-hyun
The author is a doctor in the Department of Family Medicine at Samsung Medical Center and a professor at Sungkyunkwan University School of Medicine. ― Ed.