Foods High in Vitamins and Minerals
Most foods contain some vitamins and minerals. Vitamins can be categorized into two major groups: fat-soluble (A, D, E, and K) or water-soluble (B complex and vitamin C). Minerals may be termed either macro or micro. Meats are good sources of B vitamins, iron (Fe), and zinc (Zn). Dairy foods provide about 80 percent of the average American's daily calcium (Ca). Vitamin C (ascorbic acid) is found only in plants. All the fat-soluble vitamins (A, D, E, and K) are found in an egg yolk. Vitamin B12 is found only in foods of animal origin or fermented foods such as tempeh, tofu, and miso, which contain bacteria that produce vitamin B12 as a by-product. The two major sources of sodium (Na) in the diet are processed foods and the salt shaker.
Composition of Vitamins and Minerals
Vitamins are organic (carbon-containing) compounds, each with a unique chemical composition. Minerals are inorganic elements and are depicted in the periodic table. Unlike vitamins, minerals cannot be destroyed by heat, light, or oxygen. Vitamins and minerals do not provide calories (kcal).
Functions of Vitamins and Minerals in Food
Vitamins and minerals regulate metabolic functions. Because of the vital role these compounds play in the body's processes, many foods are now enriched or fortified with additional vitamins and minerals. During processing and preparation, foods such as wheat and rice may lose some of their vitamin or mineral content. Some of the nutrients, such as Vitamin B1 (thiamin), vitamin B2 (riboflavin), niacin, and iron (calcium optional), may be added back (enriched) to the processed food. Fortification is intended to deliver nutrients to the general public in an effort to deter certain nutrient deficiencies. Salt became the first food ever fortified in 1922, when iodine deficiencies were resulting in goiter (enlarged thyroid gland) and cretinism (dwarfism, mental retardation) in children born of mothers who had not ingested sufficient iodine amounts. Other nutrients that are used to fortify foods include vitamins A and D (milk), calcium (orange juice), and/or folate, a B vitamin (cereal products).
The decision to fortify with a particular nutrient is a complex one. It starts with the realization that a significant number of people are not obtaining desirable levels of a specific nutrient, and the determination that the food to be fortified makes an appreciable contribution to the diet. It must be further ascertained that the fortification will not result in an essential nutrient imbalance, that the nutrient is stable under storage and capable of being absorbed from the food, and that toxicity from excessive intakes will generally not occur.
Certain nutrients, especially vitamins A, C, and E and the mineral selenium, may also be added to foods to act as antioxidants. These compounds neutralize free radicals, leading to an increased shelf life. Foods to which antioxidants are commonly added include dry cereals, crackers, nuts, chips, and flour mixes. Consumer interest in antioxidants and health has also caused manufacturers to add additional amounts of these nutrients to other food products.
Another compound in the vitamin/mineral category that is used to preserve foods is salt, the only mineral directly consumed by people. The function of salt in foods, however, exceeds its preservation role. It provides flavor to so many processed foods that it is now the second most common food additive by weight, after sugar, in the United States. Salt can he purchased in various special forms by the food industry to add to their products: topping salt for saltine crackers, breadsticks, and snack crackers; surface-salting for pretzels, soft pretzels, and bagels; fine crystalline salt for potato chips, corn chips, and similar snacks; blending/dough salts for flour and cake mixes; light salt (potassium chloride) for reducing sodium levels; and encapsulated salt for frozen doughs.
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