This systematic review of U.S. studies on health literacy found that 26% of adults had low health literacy and 20% had marginal health literacy. These rates were consistently associated with education level, ethnicity, and age. Low health literacy was not linked to gender or the specific measurement instrument used. The review included 85 studies with data from 31,129 participants. The prevalence of low health literacy varied widely, ranging from 0% to 68%. The study highlights the importance of improving health education and simplifying health services to address health disparities. It also notes that health literacy is a critical factor in health outcomes and that limited health literacy is a significant issue in the U.S. The review emphasizes the need for further research and policy changes to improve health literacy and reduce disparities. The findings suggest that health literacy is a key component of effective healthcare delivery and that addressing it can lead to better health outcomes for Americans.This systematic review of U.S. studies on health literacy found that 26% of adults had low health literacy and 20% had marginal health literacy. These rates were consistently associated with education level, ethnicity, and age. Low health literacy was not linked to gender or the specific measurement instrument used. The review included 85 studies with data from 31,129 participants. The prevalence of low health literacy varied widely, ranging from 0% to 68%. The study highlights the importance of improving health education and simplifying health services to address health disparities. It also notes that health literacy is a critical factor in health outcomes and that limited health literacy is a significant issue in the U.S. The review emphasizes the need for further research and policy changes to improve health literacy and reduce disparities. The findings suggest that health literacy is a key component of effective healthcare delivery and that addressing it can lead to better health outcomes for Americans.