The research, published in the May issue of the Journal of the American Dietetic Association, formed part of a wider study of children's dental health.
The parents of 400 white children in Iowa were asked to fill out periodic questionnaires about their offspring's supplement intake, and to keep diaries of their food and beverage intake between the ages of six weeks and two years.
Even in the first three months of life about 20 percent of breastfed infants were seen to receive supplements, and the prevalence increased after six months.
By 24 months, 31.7 percent of children took some supplement.
During the first nine months, the majority of users took vitamins with fluoride. After months most took multiple-vitamin supplements or multiple vitamins with extra vitamin C. Few young children took a single vitamin or mineral.
Despite this usage, study author Julie Mae Eichenberger Gilmore said the parents' food diaries belied little need for supplementation for the majority of children in the study, as most were obtaining adequate vitamins and minerals from diet alone.
The exception to this was seen to be vitamin E and folate, of which a large proportion of young children were not consuming enough from diet alone.
On the other hand, they consumed more than the dietary reference intake for some other nutrients, such as vitamin A.
According to Eichenberger Gilmore, there have been few studies reporting supplement use by very young children until recently. Those that do exist have tended to be cross-sectional and assess use retrospectively.
"This study provides unique, valuable information on pediatric use of nutrient supplements," she wrote.
However she did admit some limitations to her research. In particular, the study sample was not randomly selected, was disproportionately white and was of a relatively high socioeconomic status.
"These findings are not directly applicable to all age/racial groups; therefore, an evaluation of the target population should be conducted before making recommendations regarding nutrient supplementation."
While parents no doubt have their childrens' best interests at heart when they give them dietary supplements, a study published last year expressed concern at the number of children and adolescents using dietary supplements.
The report, conducted at Brenner Children's Hospital and published in the April 2004 issue of Paediatric Annals found that 45 percent of the 145 families surveyed reported giving their child a herbal product, and only 45 percent of these said they have discussed their use with the child's primary health care provider.
The dietary supplements retail market in the United States was worth an estimated $6.48 billion in 2004, according to market researcher Euromonitor.