Seniors and supplements: an issue that has many caregivers wringing their hands in frustrated indecision.

Should my parent take supplements? Are they safe? How much do they need? Is it worth the money?

Even if you have the time to wade through the conflicting literature surrounding supplements, it can be hard to find a straightforward answer to these questions.

Just recently, a new study surfaced saying that Omega-3 fish oil—one of the more highly-touted supplements—wasn't effective in reducing a person's mortality risk, or their propensity to have a heart attack or stroke. These results ran contrary to the prevailing wisdom that Omega-3s may help stave off heart disease and death.

The bottom line is that no pill can replace a balanced diet.

"My motto is always: food first," says Rachel Berman, R.D., Director of Nutrition for Calorie Count, "Foods found in nature are always more nutritious because our bodies are used to processing natural food."

Common senior supplements

Berman does acknowledge that supplements may be beneficial for those with unvaried or restricted diets.

There are a variety of issues that can limit a senior's diet.

Changes in ability to taste and metabolize food can lead to a loss of appetite. Allergies and ailments such as Crohn's and celiac disease can also wreak havoc on an elder's ability to digest and absorb nutrients from food.

A doctor may advise your loved one to take certain supplements to make up for the deficiencies that result from an abbreviated diet.

Here's a rundown of four supplements most frequently suggested for seniors:

Vitamin B12

What it does: Vitamin B12 performs a variety of functions, including: central nervous system maintenance, red blood cell production, and metabolism regulation. People who don't get enough B12 may suffer from constipation, loss of appetite, anemia, weakness and tiredness. Berman says that seniors need more vitamin B12 because, as a person ages, they lose their ability to effectively use the B12 found in food sources. Celiac and Crohn's disease can also inhibit natural absorption of the vitamin.

Natural sources: Vitamin B12 is found in high concentrations in red meat and clams. Fish, eggs, poultry and milk also contain significant levels.

Potential dangers of supplementation: When it comes to B12, overdosing doesn't present much of a concern. The vitamin is water-soluble, meaning that any excess will get flushed out of a person's body in their urine. However, B12 supplements may interact badly with certain kinds of medications, including: Metformin (a popular diabetes drug), proton pump inhibitors, histamines, and certain antibiotics.

Vitamin D

What it does: Vitamin D helps promote good bone health by facilitating the absorption of calcium into your teeth and bones. Healthy levels of vitamin D have been linked with a decreased risk for certain cancers and a potential reduction in the symptoms of depression. Conversely, vitamin D deficiencies may increase a person's risk for: osteoporosis, multiple sclerosis and type-2 diabetes. According to Berman, people gradually lose their ability to extract vitamin D from calcium as they get older. Things that inhibit the body's ability to absorb vitamin D include: being over age 50, overweight, or lactose intolerant. Those suffering from celiac or Crohn's disease may have trouble metabolizing the vitamin. Certain medications (laxatives, steroids, anti-cholesterol) can also make it more difficult for people to get sufficient vitamin D.

Natural sources: Because human beings are meant to get most of their daily dose of vitamin D from the sun, there are few foods that are naturally good sources of it. Salmon is a vitamin D champion—one three-ounce portion contains almost 100 percent of the recommended daily amount for seniors. Fortified foods, such as: cereals, orange juice, milk, yogurt, can also be good sources of vitamin D.

Potential dangers of supplementation: It is possible to overdose on vitamin D supplements. Complications of getting too much vitamin D may include: an elevated risk for urinary tract infections, a loss of appetite and kidney stones.

Omega-3 fatty acids

What it does: Omega-3 fatty acids get a lot of press, and with good reason. Research indicates that these "good fats" may lower inflammation and help a variety of ailments, including: dementia, arthritis, cancer, heart disease, and depression. There are three different kinds of Omega-3s: DHA, EPA, and ALA. The omegas found in certain kinds of fish (DHA and EPA) are thought to provide the greatest health perks. While ALA, the omega found in certain nuts and vegetables, is slightly less beneficial.

Natural sources: Salmon, tuna, herring, sardines and anchovies are all solid sources of Omega-3s. Spinach, Edamame (soy beans), walnuts and broccoli also contain beneficial levels of this fat.

Potential dangers of supplementation: People with diabetes as well as those taking blood-thinning or blood pressure-lowering medications should be wary of Omega-3 supplements. Studies have shown that omega-3 supplements, when used in conjunction with certain medications, may increase bleeding risk and cause a person's blood pressure to drop to dangerously low levels. They may also cause blood sugar spikes that can be dangerous for diabetics.

Co-enzyme Q10 (CoQ10)

What it does: Though many people may have never heard of it, CoQ10 is one of the more universal substances found in the human body. Every cell has some amount of the enzyme, which is essential for cell repair and growth. It is also an antioxidant, and provides protection to both skeletal and heart muscles. According to the Mayo Clinic, age, cancer, Parkinson's disease, heart disease, and diabetes may all play a role in lowering a person's CoQ10 levels. Statin medications can decrease the amount of CoQ10 in the body.

Natural sources: Many foods contain CoQ10, including: red meat, salmon, fresh sardines, tuna, mackerel, soybeans, soybean oil, sesame oil, peanuts, walnuts, broccoli, spinach, and whole grains. To get the biggest benefit, avoid over-cooking meat sources of CoQ10, and eat the non-meat sources raw. Heat alters the CoQ10 enzyme, making it less effective.

Potential dangers of supplementation: CoQ10 encourages blood clotting (a big no-no for those taking warfarin and other anti-coagulants), and can lower blood sugar and blood pressure to potentially dangerous levels. It may also interfere with chemotherapy treatment.

If you're worried that a senior is not getting enough variety in their diet, take you concerns to their primary care physician first. Do not give a loved one any kind of dietary supplement before consulting with their doctor.

Ask the physician about natural, food-based alternatives to supplementation and be sure that they are aware of all the medications your loved one is taking, especially if they suggest adding any supplements to their diet.