Environmental influences: factors influencing a woman's decision to use dietary supplements.

Use of dietary supplements by women, particularly those over 40 years of age may be widespread in the United Kingdom. However, from surveillance data, there appears to be a disparity between nutrition and health needs and the rationale for and actual use of dietary supplements by women. This apparent paradox forms the basis for an inverse supplement hypothesis (i.e., supplement use in women appears to be most prevalent among those with least need). Little research has been done to examine the factors underlying the decision to use dietary supplements. Reasons for consuming dietary supplements are often complex, combining social, psychological, knowledge and economic factors. The theory of planned behavior is a widely used model for assessing factors influencing behavioral motivation and action that may be useful for assessing specific diet- and nutrition-related practices. It provided the basis for the development of a questionnaire to explore overall dietary supplement use in a cohort of women in the United Kingdom. The analysis of factors related to beliefs underlying dietary supplement use revealed differences between supplement users and nonusers. Differences included a stronger belief by users than nonusers that taking dietary supplements ensures against possible ill health. Both users and nonusers of supplements also perceived the media (books and magazines) to be a powerful influence on a person's decision to use supplements. These findings highlight the potential of the theory of planned behavior in exploring supplement-taking behavior while throwing light on the factors influencing an individual's motivations to use dietary supplements.