Carbohydrates are the main source of fuel for all cells in your body, particularly those in the nervous system. When your body digests carbohydrates and converts them into energy, it uses certain vitamins to initiate the metabolic process to break down carbohydrates. Dietitian Ellen Coleman compares carbohydrates to gasoline for you car, and vitamins to spark plugs.
Simple carbohydrates are made up of one sugar molecule and are easy for your digestive tract to digest and absorb. Complex carbohydrates are made up of more than one sugar molecule, with each molecule linked together by strong carbon bonds. Starch is one type of complex carbohydrate your body can break down into simple sugars for energy; your body cannot break down dietary fiber, however. The latter passes through your digestive system with very little or no change in form because your body does not have the enzymes to break down fiber.
Coleman recommends that your diet should consist of between 55 and 65 percent carbohydrates, with 90 percent of the carbohydrate intake derived from complex carbohydrates. If you are an endurance or strength athlete, increase your carbohydrate intake to 75 percent.
Fat-soluble vitamins (A, D, E and K) are dissolved in fat and are stored in your fat tissues. Your body can tap into this short-term storage of vitamins if you run low in your diet. Water-soluble vitamins (B vitamins, C) are dissolved in water and cannot be stored in your body. Your kidneys filter excess water-soluble vitamins in urine, and you need to replenish them daily to avoid deficiencies. Many B vitamins play vital roles in carbohydrate, fat and protein metabolism.
Carbohydrate metabolism — called glycolysis — takes place in the cell's cytoplasm, the fluid region between the cell membrane and the nucleus. The breakdown of carbohydrates produces adenosine triphosphate, a high-energy compound all cells needs, and pyruvate, a substance you need to initiate fat and protein metabolism. B vitamins thiamine, niacin, B6, and pantothenic acid interact with each other and with digestive enzymes during the metabolic process to initiate various chemical reactions to break down carbohydrates, as well as fatty acids and proteins. According to Oregon State University's Linus Pauling Institute, any vitamin deficiencies cause a chain reaction that can inhibit energy production in your cells, causing fatigue, muscle weakness and headaches.
Excellent sources of complex carbohydrates include whole-grain products, brown rice, fruit skins, green leafy vegetables, starchy vegetables, nuts and seeds. Minimize your simple carbohydrates which are found in refined cereals and grains, various junk foods and sugary drinks.
All plant-based foods contain a wide variety of fat-soluble and water-soluble vitamins. For example, spinach is rich in vitamin K, which helps with blood clotting, and citrus fruits have a high concentration of vitamin C. However, some animal sources contain certain vitamins that plants lack, such as thiamine, vitamin D, and vitamin B12.
Too much or little intake of any vitamin causes many disorders and diseases. For example, too much vitamin A causes cerebral edema, dry and itchy skin and chronic headaches, yet too little vitamin A causes night blindness, dry cornea in the eye and improper DNA synthesis, which causes abnormal growth in children and teens. The American Dietetic Association recommends that you follow its daily recommended intake of vitamins to avoid vitamin toxicity and deficiency. Consult your doctor before adding any supplements.
- Oregon State University — Linus Pauling Institute: Vitamins
- "Ultimate Sports Nutrition"; Ellen Coleman; 2004
- American Dietetic Association: Vitamins and Nutrients