The study, commissioned by the trade association Council for Responsible Nutrition (CRN), also found that while 80 percent of those asked said they thought eating a balanced diet was important, only 20 percent said they actually do eat a balanced diet every day.
The supplement industry is poised to benefit from these findings, which show there is room for growth in the market as customers are aware of the need to improve their habits.
Although the supplements industry has never suggested that vitamin pills could replace a healthy balanced diet, the CRN maintains that complementary use could be beneficial, and may bridge any inadvertent gaps.
"Multivitamins can help fill that nutrient gap, and in a way that's safe, convenient and affordable," said CRN vice president for scientific and regulatory affairs, Andrew Shao, "The survey clearly makes the point that most people recognize they do not obtain the recommended amount of essential nutrients from their diet alone."
According to the 2005 US Department of Agriculture's Dietary Guidelines for Americans, the benchmark federal recommendations for healthy living, intakes of vitamins A, C and E, along with calcium and magnesium, are especially low in the diets of American adults.
"Taking a multivitamin and eating right should not be an either-or situation," said Dr Cynthia Thomson, a clinical nutrition specialist at the University of Arizona, "A sensible and responsible approach is to do both."
But Dr Thompson questioned whether people really understand what a healthy diet is.
"Likely for many there is still confusion and that in and of itself can be a barrier to change," she told NutraIngredients-USA.com.
"Today we are also bombarded with food advertisements that promote consumption as well as a high availability of energy dense, low cost foods… There is a growing emphasis in public health to change the 'social context' to promote healthier lifestyle choices, but the budgets for these efforts are well below that of companies trying to sell their food products."
According to CRN a lot of Americans are already, in fact, taking multivitamins: Of the 1,025 adults surveyed, 41 percent said they take a multivitamin every day.
But the findings reveal that some groups are more likely to take a multivitamin than others - lighting the path for supplement makers to target certain their brands accordingly and open up to new sectors where the message is not getting across.
For example, women are more likely than men to regularly take a multivitamin (50 per cent of women, compared to 41 per cent of men). And 54 percent of respondents aged 50 or above regularly take a multivitamin compared to 39 percent under the age of 50.
Dr Thompson said that, given these numbers, we are "relatively successful… especially when we review the data on the high non-compliance rates for medications".
But she also highlighted a number of barriers: cost for those of a lower socio-economic status ("although this is a behavior that only costs about 10 cents a day, when you purchase a 6 month supply it can seem very costly"); time; beverage availability or difficulties with dosage format; tolerance - some people complain of upset stomach/nausea when they take multivitamins, generally = related to taking it on an empty stomach.