Omega-3 fats are a heart healthy nutrient that doctors noted is difficult to get through diet alone but easy to supplement by taking fish or flax seed oil. Especially for those with an elevated risk of heart disease, doctors recommended adding this supplement to patients' diets.
B vitamin supplements are a good option for vegetarians and vegans since they avoid eating fish and meat, the best source for vitamin B. Several doctors contacted noted that they suggest supplementing to their patients who have these kinds of diet restrictions.
Dr. Richard Besser, ABC News' senior health and medical editor, said the only way to get vitamin B12 is from meat. Non-meat eaters should therefore take a multivitamin or vitamin B12, he added.
Another way to get vitamin B12 is to eat a fortified cereal that includes it, he added.
Vitamin D and calcium were repeatedly noted as problematic nutrients to keep up with using diet alone -- especially if a patient doesn't get enough exposure to sunlight or can't or chooses not to eat dairy.
Michos says that "unlike the other vitamins, vitamin D is hard to get sufficient quantities from food alone. Fortified milk, orange juice, and cereal have vitamin D, but in low amounts," so "vitamin D supplementation is widely used to treat and prevent osteoporosis and fractures."
Most doctors also mentioned that during certain phases of a patient's life, extra calcium and Vitamin D are needed, such as during pregnancy or menopause, and during the first decade or so of life, and these times, a supplement might be needed.
Vitamin D, especially, has become a hot topic among pediatricians after several studies suggest widespread deficiency in American children. A 2009 study from the America Academy of Pediatrics showed that over 60 percent of kids in the U.S. are lacking in this vitamin, especially among minority populations.
Anecdotally, doctors also mention seeing patients with low Vitamin D. Schwartz recommends routinely checking patients for a deficiency and notes this issue is becoming more common.
Dr. Andrew Racine, director of the section of general pediatrics at Montefiore Medical Center, notes that mother's milk or cow milk-based formulas do not provide the recommended daily amount of Vitamin D that infants need. He and several other doctors suggest using Vitamin D drops or pre-made vitamin mixtures to supplement an infant's diet.
Besser agrees that most people do not need to take a multivitamin if they are healthy, eat a balanced diet and get enough exposure to the sun for vitamin D.
"If you have a very balanced diet … you probably don't need a multi-vitamin," Besser said, but added that "there are many people for whom I recommend them."
Besser also said he recommends vitamins for some children.
Because children are developing rapidly and tend to be picky eaters, there may be times when they will benefit from a multivitamin in chewable or liquid form.
"Children are growing, they're developing and their taste buds are developing as well," he explained. Besser's own son went through a phase where he didn't want to eat vegetables.
"My son was in the beige phase," he said. "During that period I put him on a multi-vitamin."
Children can take chewable vitamins and vitamin drops are available for newborns, he said, adding that pregnant women should take a prenatal vitamin.