Vitamins are organic substances required for normal metabolism and optimal health. Scientists have extensively researched vitamin needs and developed guidelines and recommendations. Recommended Dietary Allowance or RDA, is the amount of a nutrient required to prevent deficiencies. The RDA is being replaced by the most recent dietary recommendations of the Food and Nutrition Board of the Institute of Medicine called Dietary Reference Intake, or DRI. RDA and DRI are used interchangeably. Age groups and genders require different amounts of nutrients. The DRIs presented here will focus on men between the ages of 19 to 70.
Vitamin A
Vitamin A is a fat-soluble vitamin required for normal vision and immune function, gene expression and reproduction. The 900 mcg RDA for men is based on the amount required to ensure four months' adequate supply of stored vitamin A. Vitamin A sources include fish, liver, dark fruits and leafy vegetables.
B Vitamins
B vitamins are a group of water-soluble vitamins essential to helping create energy from food. Often referred to as B complex, they include biotin, thiamin, riboflavin, niacin, pantothenic acid, folic acid, B6 and B12. B vitamins can be found in fruits, vegetables, whole-grains, eggs, fish, meat and poultry. Men require 30 mcg of biotin, 1.2 mg of thiamin, 1.3 mg riboflavin, 16 mg a day niacin and 5 mg of pantothenic acid per day. The folic acid requirements for men of 400 mcg can be obtained in one to two servings of fortified breakfast cereals. B6 cannot be made in the body so it must be obtained through diet. Salmon, bananas and turkey help supply the recommended 100 mg per day. B12 is essential in DNA synthesis and just 3 oz. of salmon can fulfill the required 2.4 mcg.
Vitamin C
Vitamin C is a water-soluble vitamin required for synthesis of collagen and bone, and is an effective anti-oxidant. Citrus fruits, tomatoes and broccoli are common sources of Vitamin C and can easily satisfy the required 90 mg per day.
Vitamin D
Vitamin D is a fat-soluble vitamin required for calcium balance maintenance. It plays important roles in bone formation, immunity, cell-differentiation, blood pressure regulation and insulin secretion. Vitamin D can be produced in the skin by sunlight. If exposure to the sun is inadequate, D must be obtained through foods such as fortified milk, fish and eggs or supplements. The RDA for men for vitamin D is 5 to 10 mcg per day.
Vitamin E
Vitamin E is the name of a group of organic substances called tocopherols and tocotrienols, which mainly function as anti-oxidants. Vitamin E can help prevent heart disease, some cancers and cataracts. Men require 15 mg a day of vitamin E, which is naturally found in vegetable oils and nuts.
Vitamin K
Another fat-soluble vitamin, K is essential for blood clotting. Vitamin K is normally produced by bacteria in the intestines. It is also available in olive and canola oil and dark green vegetables. Men require 90 mcg per day.
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