Up until the early 1900s, doctors and scientists didn't realize that vitamins and minerals existed in foods, or that these nutrients play a vital role in enhancing your health and preventing disease. However, many Americans still aren't getting enough vitamin A, vitamin C and iron. In 2005, the U.S. Department of Agriculture reported that 44 percent of Americans don't get enough vitamin A and 31 percent lack adequate vitamin C. When it comes to iron, about 17 percent of adult women don't meet their requirements. Knowing how much you and your family should have -- and what foods are good sources -- can help you develop a balanced diet.
The Institute of Medicine's Food and Nutrition Board recommends that adult men should have 900 micrograms of vitamin A each day, while women need about 700 micrograms. Children need between 300 to 900 micrograms, depending on their gender and age. You can get vitamin A from vegetables, especially ones that are yellow, orange or dark green. A 1/2-cup serving of baked sweet potato supplies 961 micrograms of vitamin A; raw carrots have 538 micrograms in each 1/2 cup. A variety of foods are also fortified with vitamin A, including breakfast cereals and low- or non-fat milk.
A woman should have 75 milligrams of vitamin C each day; a man should have 90 milligrams. Children as young as 1 year old need at least 15 milligrams daily. Vitamin C is a water-soluble nutrient that can't be stored in your body, so you need to eat some each day. Most fruits and vegetables contain vitamin C, and if you eat about 2 1/2 cups of produce daily, you should easily get enough, assures the Linus Pauling Institute. Excellent sources include citrus fruits like oranges or grapefruit, strawberries, red bell peppers and broccoli.
Adult women between 19 and 50 years old need twice as much iron each day as men of the same age: while a man requires 8 milligrams, a woman needs 18 milligrams. During pregnancy, the recommended daily allowance is even higher, at 27 milligrams. Children should have between 7 and 15 milligrams. Meat, poultry and seafood are all rich sources of iron. Oysters contain one of the highest concentrations, providing 5 milligrams in every serving of six oysters. If you're a vegetarian or vegan, you can get adequate iron by eating plenty of beans, legumes, dried fruit, whole grains and dark green, leafy vegetables. The iron in plant-based foods isn't absorbed as easily as the iron in animal foods, but you can increase the amount you absorb by eating iron-rich plant foods with a source of vitamin C.
It may seem easier to fulfill your requirements of vitamin A, vitamin C and iron with dietary supplements, but MayoClinic.com cautions that it's better for your health to get your nutrition from fresh, whole foods whenever possible. Supplements do not contain the antioxidants, phytochemicals and fiber that you get from eating fresh food. In addition, dietary supplements can often cause side effects like nausea, vomiting, diarrhea, an upset stomach and mood swings. They may also interfere with the proper function of medications you're taking. If you consume too much -- something that is difficult to do when you get your nutrients from food -- you may develop potentially harmful toxicity symptoms. If you're concerned about your intake of any vitamin or mineral, talk to your doctor before you begin using dietary supplements.