You may have heard stories about the benefits of fish oil, but what is good about it? Fish oil contains two types of healthy omega-3 fatty acids, docosahexoenoic acid and eicosapentaenoic acid. Data from several large-scale studies have shown that eating fish or taking fish oil supplements may lower your triglyceride levels (a good thing) and reduce the risk of heart attack, stroke, and abnormal heart rhythms in people with cardiovascular disease.

Because not everyone likes to eat fish, and not everyone can easily buy fish to prepare and eat regularly at home, fish oil supplements are one way to increase the amount of healthy omega-3 fatty acids in your diet.

Be sure to talk to your doctor or another healthcare professional before you start taking fish oil supplements, especially if you take other medications. And if you are allergic to fish, be safe and avoid fish oil products and other omega-3 supplements. You can get omega-3 fatty acids from other sources including walnuts, flaxseed, and green leafy veggies.

Also talk to your doctor if you experience any side effects associated with fish oil or omega-3 supplement use. These side effects include an upset stomach and diarrhea, and a slight increase in fasting blood glucose if you have type 2 diabetes.

Everyone needs vitamin D, and if you don’t get enough in your diet, you may need a vitamin D supplement. Vitamin D is important because it helps your body absorb calcium. If you don’t get enough vitamin D, you are increasing your risk for developing osteoporosis as you age. In general, adults age 50 years and older need more vitamin D than younger people to maintain adequate calcium as their bones become more brittle.

The best way to supply your body with vitamin D is through food. Cheese and butter are high in vitamin D, and all milk sold in grocery stores in the U.S. has been fortified with vitamin D. Fortified breakfast cereals are great sources of vitamin D, as are fish and oysters. Most people can get vitamin D from food, but talk to your doctor about vitamin D supplements if you are in one of these high-risk categories:

• Older age (older than 50 years)
• Darker skin
• Limited sun exposure
• People with liver disease, celiac disease, cystic fibrosis, Crohn’s disease, or other conditions that make it hard for their bodies to absorb fat from foods.

Be sure to talk to your doctor or another healthcare professional before you start taking new.

When it comes to healthy eating, vitamin supplements can’t and shouldn’t replace real foods. Although many vitamin supplements won’t do you any harm, you may need to supplement your diet with additional vitamins and minerals if you fall into any of these categories:

• You are pregnant or trying. Prenatal vitamins are important to promote fetal development and a healthy pregnancy and healthy baby.
• You are a vegetarian. If you are a strict vegetarian, your diet may be deficient in any or all of the following nutrients: iron, zinc, calcium, vitamin D, and vitamin B12. You can get enough of these vitamins from non-meat foods, specifically green leafy veggies, fortified soy foods, legumes, nuts, and whole grains. If you don’t eat enough of these foods, consider taking supplements for one or more of these nutrients.
• You don’t eat enough food. If you are on a very low calorie diet (less than 1,200 calories per day) you may not be getting enough nutrition from food. Do not embark on a very low-calorie diet unless you are under a doctor’s regular supervision.
• You have medical problem that affects your body’s ability to absorb food, or if you have intolerance to food groups such as dairy products, your doctor may recommend dietary supplements.
• You just don’t eat well. If you only eat once or twice a day and you eat fewer than 5 servings of fruits and vegetables, you may not be getting adequate nutrients from food.

If you are pregnant or thinking of getting pregnant, most doctors recommend folic acid supplements, either as a separate supplement or in a prenatal multivitamin. What’s the big deal about folate? Research has shown that women who consume plenty of folate in their diet or from supplements can reduce the risk that their babies will have neural tube defects such as spina bifida.

Be sure to include folate-rich foods in your diet, too. Good sources of folic acid include beans and legumes, whole grains, dark green leafy vegetables (spinach and broccoli are good choices) bananas, melons, poultry, pork, shellfish, and liver.

Folate or folic acid (also known as vitamin B9) helps the body absorb and create new proteins. Folate helps red blood cells produce DNA, which is why it is especially important that women who are planning to become pregnant consume enough of it. Prenatal vitamins are an exception to the general rule that most people can get adequate vitamins from food sources alone.

Be sure to talk to your doctor or another healthcare professional before you start taking new supplements.

Although foods are your best sources of vitamins and minerals, some people do need or want to take vitamin or mineral supplements. If you are one of those people, keep these tips in mind for choosing and using supplements:

• Read the labels. The product label (although it is not standardized like a prescription drug label) should tell you the active ingredients, serving size, and the dosage. If it doesn’t, look for another brand.
• Don’t take megadoses. You can have too much of a good thing. Choose multivitamins that provide 100 percent of a variety of vitamins and minerals (such as Centrum One-A-Day) rather than supplements that claim 500 percent of one vitamin but less than 100 percent of other nutrients.
• Check the USP. The U.S. Pharmacopeia (USP) is an organization that tests supplements for strength and purity, so choose supplements with a USP on the label when you can. And remember that the USP is not the same as regulation by the U.S. Food and Drug Administration.
• Beware of deterioration. Check the expiration date and discard supplements (or any medication) that have expired. Don’t buy supplements that don’t have expiration dates; you don’t know how old they are, and supplements lose their effectiveness over time.
• Avoid gimmicks. Vitamins are vitamins; added herbs, enzymes, or other products won’t add to the benefit of a dietary supplement, but they probably will add to the cost.

Be sure to talk to your doctor or another healthcare professional before you start taking new supplements.

If you are taking dietary supplements, take as much care as if you were taking any prescription medication. Keep these safety tips in mind to avoid making mistakes with medications or supplements:

• Don’t dose in darkness. Never take medication in the dark, even if you think you know exactly which bottle you are grabbing; you could be wrong.
• Use standard measuring devices to measure daily doses to ensure that you take the same amount consistently each day. A set of measuring cups and spoons works well to measure doses.
• Keep all medicines in their original containers with their original labels. Wipe the top and neck of liquid medicine or supplement containers to help keep the labels clean and readable.
• If you take medication with water, drink a full 8-ounce glass to ensure that the medication or supplement is fully absorbed by the stomach.
• Shake it up. Shake all liquid supplements or medications before using to ensure that the ingredients are well mixed. Keep in mind that some liquid medications require refrigeration.
• Store dietary supplements in a cool, dry place, where children can’t reach them. Don’t store them in the bathroom—the heat and humidity from the shower can cause supplements to deteriorate.
• If you have problems swallowing a pill or capsule, look for the same supplement or medication in a liquid form.
• If you take multiple medications or supplements, keep a medication calendar to keep track of your daily dosages. Try to take medication or supplements at the same time each day, but a half hour either before or after is unlikely to upset your stomach or your daily routine.
• If you realize that you have taken the wrong supplement or an incorrect dose, contact your doctor immediately.

Be sure to talk to your doctor or another healthcare professional before you start taking new supplements.

Your body can’t store vitamin B12, so you need to consume this vitamin in food or in a supplement every day.

When you consume foods or supplements with B12, your body uses what it needs and eliminates the rest through urine.

Vitamin B12 is important because it plays a key role in the body’s metabolism, which includes your body’s ability to perform basic functions such as breathing and circulation. Vitamin B12 also helps your body maintain a core body temperature on an ongoing basis. Good sources of vitamin B12 include eggs, meat, shellfish, poultry, milk, and milk products.

If you follow a strict vegetarian or vegan diet and don’t consume any eggs or milk products, you may need vitamin B12 supplements because the best food sources for B12 are animal products. Although some non-animal products contain B12, the amounts are not usually enough to meet the body’s needs. Be sure to ask your doctor to help you choose a vitamin supplement with B12 that is right for you.

Vitamin C has antioxidant properties and it does the bulk of the repair work on your body. Vitamin C also helps your body perform maintenance and repair on bones, teeth, and cartilage. And it helps wounds heal.

Vitamin C is water-soluble, which means that it is not stored in the body and you need to consume it every day. Eating foods rich in vitamin C is the most efficient way to get it. Citrus fruits are among the foods with the highest amounts of vitamin C. Half a cup of fresh orange slices (a small orange) gives you about 48 milligrams.

Other fruits high in vitamin C include strawberries, raspberries, blueberries, and pineapple. Although many people associate vitamin C with fruit, there’s also plenty of it to be found in green peppers (60 milligrams per half cup serving) and tomatoes (23 milligrams per half cup serving).

But be sure to check with your doctor before taking any vitamin C supplements. If you don’t get enough vitamin C, you may be less able to fight off infections and colds. You may experience dry, brittle hair and skin, as well as nosebleeds, bleeding gums, and poor quality tooth enamel.

Herbal products have active ingredients that can affect your body in positive and negative ways, just like a prescription medication, so they should not be taken lightly. And they are not for everyone. It’s best to avoid herbal supplements if you meet any of the following criteria:

• Are you taking prescription medications? Herbal supplements can cause potentially dangerous interactions with prescription drugs, even birth control pills.
• Are you older than 65 years? As you age, you metabolize medications differently, and this goes for supplements, too. Few safety studies of herbal supplements have been conducted on older adults. If you are still keen to try an herbal supplement, be sure to discuss it with your doctor first.
• Are you having surgery soon? Herbal supplements can complicate your surgery by causing you to bleed more easily or by interfering with the effectiveness of anesthesia.