Vitamins and Supplements: Getting Enough A, B, C, D, E, and Omega-3 in Your Diet?

Tired, dry skin, or fighting a cold again? If you feel like something is a little off, you may lack some key vitamins or minerals. They help your cells and organs work the way they should and boost your immune system, among other things. Usually, the best way to get them is through foods that have a lot of them.

If you're tired after a full night's rest, it could be from a lack of iron (found in lean meat, beans, and fortified cereals) or vitamin B12 (in beef liver and clams). They're both important for healthy red blood cells, which get oxygen to your body's tissues. Check with your doctor if you are tired for no reason and they can check to see what is causing you to feel that way.

If you have these a lot, talk to your doctor about magnesium, found in beans, nuts, and green leafy veggies. This mineral helps your nerves work the way they should and keeps your blood sugar levels in check. The Association of Migraine Disorders says 400 milligrams a day can help some people who get migraines.

It might be from allergies or from wearing contact lenses for a long time, but another possibility is that you're not getting enough omega-3 fatty acids. Found in oily fish like salmon, mackerel and tuna, these are important for healthy vision. In addition to dry eyes, low levels of omega-3s also have been linked to age-related macular degeneration, among other issues.

Scaly, rough patches of skin -- dermatitis -- can be caused by something that irritates it or illness, but it also can come from a lack of vitamin B2 (riboflavin). B2, which helps your cells grow and work the way they should, is found in eggs and some green vegetables, like asparagus and broccoli.

This can happen naturally as you age, but it also can be caused by a nutritional problem, especially in women under 50. Boost your iron (through lean meats, beans, or nuts) to help make sure your hair and the skin around it stay healthy.

The most likely cause of this problem is gum disease, but a severe lack of vitamin C (found in citrus fruits and some vegetables) can also bring it on. This is rare for people in the U.S., though, so see your dentist to find out for sure before taking a supplement.

A lack of vitamin B1 -- also known as thiamin -- can lead to this and other problems. It's found in whole grains, pork, fish, some nuts, and beans. Potassium (found in bananas) is also important for healthy muscles. Talk to your doctor if you don't think you're getting enough through these foods.

You might cough and sneeze more often if you don't get enough vitamins C and E, which have antioxidants that boost your immune system. A balanced diet won't prevent colds, but it can keep your body healthy enough to help fight them off.

These little ulcers form in the soft tissue of your mouth or the base of your gums. No one knows for sure what causes them, but they've been linked to a lack of B12, zinc (found in oysters, nuts, and beans), folate (in asparagus, Brussels sprouts, and oranges), and iron.

One of vitamin B12's many jobs is to help your nervous system (made up of your brain, spinal cord, and nerves) work the way it should. If you don't get enough, researchers think, the signals between your ears and your brain can be affected, and this might lead to hearing loss or tinnitus -- ringing or buzzing in your ears. If you're having hearing problems, see your doctor to find out what's causing them.

Calcium is a building block for bones, and vitamin D helps your body absorb it. If you don't get enough of these, you can be more likely to have osteoporosis, a disease that makes your bones weak and brittle. The best way to get vitamin D is through supplements, but you can get calcium through dairy products and some fortified foods. Talk with your doctor about what's right for you.

A lack of vitamin B6 can cause this as well as skin rashes. It's found in poultry, fish, starchy vegetables like potatoes, and noncitrus fruits like grapes and apples. Check with your doctor before starting a B6 supplement, though -- it can cause problems if you take certain medications.