Vitamins and minerals perform many vital jobs to keep you healthy. Some, like Vitamin A, are essential for vision, B vitamins for metabolism, and folic acid for cell growth.
Minerals like calcium, chromium, selenium, and iron are needed in larger amounts. The most important vitamins can be obtained through a healthy diet of whole foods.
Vitamin A
A fat-soluble vitamin, Vitamin A, is needed for many body functions, including cell growth and development, good vision, reproductive health, and the immune system. It helps keep the skin and mucus membranes healthy and maintains healthy teeth and skeletal tissues. The body cannot make this vitamin on its own, so it is essential to consume it from foods. Vitamin A is found in animal liver, whole milk, fortified dairy products, and vegetables and fruits rich in beta-carotene (dyes). The best-known form of this vitamin is preformed retinol, which is also known as retinal. It is also available in the form of provitamin A carotenoids, which are plant pigments that our bodies convert into retinol. These are found in a variety of brightly colored, orange, and green vegetables and fruits, as well as dark leafy greens.
Vitamin A is critical for reproduction and healthy fetal development, as it plays a role in sperm and egg formation. It also supports the function of certain white blood cells that fight infection and helps maintain the health of the mucus membranes in the lungs and intestines. Several studies have found that people with suboptimal intakes of Vitamin A are at increased risk for cancer, including lung cancer. Vitamin A also acts as an antioxidant, protecting the body from damage by free radicals.
Getting enough vitamin A is crucial to good health, as deficiency can lead to a host of diseases, including cataracts and age-related macular degeneration. Eating a balanced diet that includes meat, dairy, and plenty of veggies should provide you with adequate amounts of this vital vitamin. If you are pregnant or breastfeeding, it is important to avoid too much supplemental preformed retinol, as high doses can increase your risk of birth defects.
Vitamin C
Vitamin C (ascorbic acid) is an essential nutrient your body uses to form blood vessels, tissue, and bone. It also helps your body absorb iron and fights free radicals. Free radicals are unstable molecules that can damage cells and cause many chronic diseases, including heart disease and cancer. Vitamin C is a powerful antioxidant that can boost your body’s natural defenses against these molecules.
Epidemiologic studies suggest that higher intakes of fruits and vegetables may lower your risk of certain cancers, especially lung, colon, and esophageal cancer. However, there is not enough evidence to show that dietary vitamin C supplements lower your risk of these cancers.
Your body cannot make vitamin C on its own, so it is important to get it from your diet. You can find vitamin C in a wide variety of foods, such as citrus fruits and juices, berries, tomatoes, potatoes, greens, and peppers. You can also find it in a variety of fortified breakfast cereals and some dairy products. Adults recommended dietary allowance (RDA) is 90 milligrams per day.
Low levels of vitamin C have been linked to an increased risk of heart disease, cancer, atherosclerosis, or the build-up of plaque in blood vessels. A high intake of vitamin C, through a balanced diet or vitamin supplements, can help protect against these conditions.
Vitamin C also plays a role in the immune system, stimulating the activity of white blood cells. It is thought that this activity might prevent the occurrence of some allergies, such as skin and respiratory allergies. It is also possible that vitamin C can limit the formation of carcinogens from cigarette smoke and reduce the effects of oxidative stress on cells. Its role in the immune system is further supported by studies showing that people who eat diets rich in vitamin C are less likely to develop colds.
Vitamin D
Vitamin D is well known for its role in promoting bone health. It helps your body absorb and use calcium, which strengthens bones and teeth. It also prevents rickets in children and osteomalacia in adults.
However, recent studies suggest that vitamin D does much more. It may reduce the risk of certain diseases, including heart disease and cancer, help treat depression, improve mood, and even aid in weight loss.
It’s a fat-soluble vitamin, meaning it’s stored in your body’s fatty tissues. This allows your body to build up reserves if you’re not getting enough in your diet. However, high doses can cause a dangerous buildup of calcium in the blood (hypercalcemia).
The vitamin D you get in your diet comes from foods like fish, liver, egg yolks, and fortified milk. It’s also available in supplements. But the best source is sunlight. The sun’s UVB rays turn a naturally occurring form of cholesterol in the skin called 7-dehydrocholesterol into vitamin D. Your liver and kidneys then transform it into the active form of vitamin D that your body needs.
From about late March or early April until September, we make most of our vitamin D from sunlight. But during the winter, many people don’t make enough because their skin is covered by clothing, and the ozone layer blocks UVB radiation. In addition, darker skin produces less vitamin D because the pigment in their skin acts like a natural sunscreen, reducing the amount of UVB that passes through to the deeper layers where the vitamin D is made.
The Institute of Medicine’s 2010 recommendations increased the daily allowance of vitamin D for all ages from 600 to 4,000 IU per day. But your actual need may vary depending on the season, your health problems, and other factors. For example, people with gastrointestinal conditions such as celiac disease or who have had bowel surgeries require higher intakes of the vitamin.
Vitamin E
Vitamin E is a fat-soluble vitamin that works as an antioxidant. It protects body tissue from damage by substances called free radicals, which are produced during normal metabolism and when the body is exposed to pollution, tobacco smoke, and radiation. Vitamin E also helps form red blood cells and widens blood vessels to prevent blood clots from forming inside them. Vitamin E is found in plant-based oils, nuts, seeds, vegetables, and fruits. It is added to many processed foods, like cereals, and is available as a dietary supplement. Most people get the recommended amount of vitamin E from a healthy diet and do not need to take supplements.
The most common use of vitamin E is to treat cardiovascular disease and some cancers. Research suggests that the vitamin can slow down or prevent the oxidation of LDL (bad) cholesterol, which is an important step in the development of atherosclerosis (hardening of the arteries). It can also help reduce inflammation and decrease the chances of a heart attack or other cardiovascular events.
Some clinical trials suggest that vitamin E can lower the risk of certain cancers, including prostate cancer. However, more research is needed before these claims can be made. The National Institutes of Health Office of Dietary Supplements recommends that adults age 14 and older get 15 milligrams a day of vitamin E from food or supplements. Nursing mothers should get 19 milligrams daily.
Taking high doses of vitamin E may increase the chance of bleeding in some people, especially those with certain disorders, such as liver disease and Crohn’s disease. It can also interfere with medications such as blood thinners and anticoagulants. If you plan to take vitamin E, talk with your doctor first.
Vitamin E can interact with a number of drugs, herbs, and supplements, such as aspirin, ibuprofen, and warfarin (Coumadin). It also might interfere with some types of chemotherapy. The NIH warns that high-dose vitamin E supplements might increase the risk of bleeding in some people who are getting chemotherapy or radiotherapy for cancer. The NIH recommends you consult your oncologist before taking any vitamin E supplements during cancer treatment.