Vitamins are complex organic substances, found in food, that are necessary for good health. Vitamins help your body metabolize food into energy and grow healthy tissues. Your body needs only very small amounts of vitamins, yet a lack of even one of them can result in weakness, disease and sometimes death. Vitamins by themselves do not supply your body with energy, but they help your body to release energy from carbohydrates, proteins and fats.
Scientists began to identify and isolate vitamins around the beginning of the 19th century. By the 1940s, various types of vitamin supplements were being sold in drugstores. Today 13 vitamins are recognized:
- Vitamin A (retinol): Eyesight, growth, and appetite
- Vitamin B complex, which includes:
- Thiamine (B1): Nervous system, digestion, muscles, heart
- Found naturally in brewer's yeast, eggs, fish, legumes, meats, nuts, poultry and whole grains.
- Riboflavin: Growth, skin, nails, hair, eyesight, and the breakdown of protein, fat and carbohydrates.
- Niacin: Regulation of cholesterol
- Vitamin B6: Nerves, skin, absorption of proteins and carbohydrates
- Folic acid: Production of red blood cells
- Vitamin B12: Production of red blood and formation of the nerves
- Biotin: Metabolism, synthesis of fats and glycogen
- Vitamin C: Immune system, healing of wounds, reduction of cholesterol, increased cell lifespan
- Vitamin D: Strong bones and teeth
- Vitamin E: Powerful antioxidant, fertility, skin
- Vitamin K: Blood clotting, regulation of calcium in the blood
Most vitamins are found in the foods you eat every day. A few are synthesized by your body. Your body makes Vitamin D when you are exposed to sunlight, and Vitamin A from the beta-carotene in orange, yellow, and green vegetables and fruits. Bacteria in your digestive system manufacture Vitamin K. Vitamins B and C are water-soluble and cannot be stored in your body, so you need to consume them every day.
Ideally, you can get all the vitamins your body needs by eating a varied diet of fruits, vegetables, whole grains, low-fat dairy, eggs, and lean meat and fish. Some processed foods, like milk, bread and orange juice, are fortified with additional vitamins. Unfortunately, many of the fruits and vegetables sold in supermarkets do not contain as many vitamins as they should because they are grown with artificial fertilizers and harvested before they mature. To make sure you are getting all the vitamins your body requires, you may need to take a daily vitamin supplement.
Vitamin supplements are recommended if you are pregnant, have food allergies or digestive problems that prevent you from absorbing nutrients efficiently, eat a limited vegan or vegetarian diet, are over 50, eat poorly, or consume less than 1,600 calories per day.
Vitamin supplements are meant to augment a healthy diet and are not a replacement for nourishing food. Whole foods contain complex nutrients, fiber, water, minerals and antioxidants that you will not get from a vitamin supplement.
Too much of a good thing can be harmful. Select a vitamin supplement that provides the minimum daily requirements for each vitamin. Excessive doses can cause unpleasant symptoms, such as indigestion and insomnia, and even permanent damage to your body. Children require even smaller amounts because their bodies are smaller.
Health problems such as fatigue, anemia, mood swings, and skin rashes may be signs of vitamin deficiency. Some vitamins undermine the effects of medications; for example, people taking blood thinners should not have a vitamin supplement containing Vitamin K. Talk to your doctor or nutritionist about whether you need vitamin supplements and what doses to take. He or she can make a recommendation after assessing your dietary habits, physical condition, lifestyle and medical status.