So far you have learned about the macronutrients: carbohydrates, proteins and fats. The next few lessons will focus on the micronutrients: vitamins and minerals. They are called micronutrients because you only need them in very small amounts. That doesn’t mean they aren’t important; in fact you can’t live without vitamins and minerals.
You will remember that we measured protein, carbohydrate and fat needs in grams. Vitamins and minerals are measured in milligrams (mg), micrograms (mcg) and international units (IU). Ready to learn more? Let’s start with the water-soluble vitamins.
Vitamins are placed in two categories, water-soluble and fat-soluble based on whether or not the vitamins can dissolve in water. Water-soluble vitamins include the B complex of vitamins and vitamin C. You don’t store water-soluble vitamins in your body very well so they need to be replaced constantly through your diet. That is one of the reasons you need to eat good foods every day, not just once in a while.
You don't need to guess at how much of the vitamins you need because the Recommended Dietary Allowance (RDA) or Adequate Intake (AI) has been determined for all vitamins and minerals. The RDA represents the amount of the nutrient that will meet the health needs for almost all individuals in a group. The groups are mostly based on gender and age based on research. The AI is more of an estimate of the amount of a nutrient that you need.
All of the water-soluble vitamins are available as dietary supplements. When you buy any dietary supplement, follow the label instructions for dosages. Mega doses of dietary supplements can have strong physiological effects on your body; don’t take large amounts of any dietary supplement without speaking to a doctor or nutritionist first.
Vitamin C
Ascorbic acid is better known as vitamin C and it is found in fruits and vegetables. Your body can’t make vitamin C, so you have to eat the foods that contain it every day. Vitamin C is essential for healthy collagen, immune system function, strong blood vessel walls and formation of bones and teeth.People who don't eat any foods containing vitamin C will develop a disease called scurvy. The symptoms of this disease include tooth loss and bleeding gums. Eventually they have bleeding into the organs. Scurvy is very rare, however if you diet is continuously low in vitamin C, you may experience irritability, depression, weight loss, fatigue, and general weakness.
Because of the connection of ascorbic acid with your immune system, many people take large doses of vitamin C supplements with the hope of preventing colds and flu. Mega doses are also commonly used in alternative medical treatments for cancer and other diseases, however these vitamin C treatments haven't stood up to scientific research.
While vitamin C supplements are generally safe up to 2000 mg, some people may have an increased risk of kidney stone formation when they take large amounts.
Vitamin C is also a powerful antioxidant that protects your body from the free-radical damage that comes from smoking, environmental pollution and from eating unhealthy foods. Antioxidants also help protect your body from its own free radicals that are produced from exercise and general metabolic processes.
Vitamin C and Diet
Vitamin C can be found in fresh fruits and vegetables. Sources include citrus fruits, strawberries, peppers, tomatoes, leafy green vegetables and potatoes. It is not found in meat or animal products. Vitamin C is present in some processed foods, too. Food manufacturers are required to list the amount of vitamin C in any packaged food, so it is fairly easy to track how much vitamin C you are getting from packaged foods.Fresh, uncut or frozen fruits and vegetables are your best choices for vitamin C. Since ascorbic acid is an antioxidant, it doesn’t last long in the presence of oxygen. This means that once you cut or peel fruits and vegetables and expose them to air, the vitamin C content will diminish.
The RDA for vitamin C
- children age 1 to 3 need 15 mg
- children age 4 to 8 need 25 mg
- males age 9 to 13 need 45 mg
- males age 14 to 18 need 75 mg
- males age 19 and up need 90 mg
- females age nine to 13 need 45 mg
- females age 14 to 18 need 65 mg
- females age 19 and up need 90 mg
- pregnant females need 85 mg
- one cup orange juice – 124 mg
- one cup strawberries – 98 mg
- one-half cup red bell pepper slices – 95 mg
- one medium baked potato with skin – 17 mg
- one kiwi – 71 mg
- one cup cooked green beans – 12 mg
- one cup raw green beans – 18 mg
- one medium apple with peel – 6 mg
- one medium banana – 10 mg
- one cup raw broccoli – 81 mg
- one-half cup sweet corn – 5 mg
Your need for vitamin C increases if you are pregnant or breastfeeding, are a smoker, or if you have recently had surgeries or major burns.
