Approximately 10.2 million persons in the United States sometimes or often do not have enough food to eat, a condition known as food insufficiency. Using cross-sectional data from the Third National Health and Nutrition Examination Survey (NHANES III), we examined whether dietary intakes and serum nutrients differed between adults from food-insufficient families (FIF) and adults from food-sufficient families (FSF). Results from analyses, stratified by age group and adjusted for family income and other important covariates, revealed several significant findings (P < 0.05). Compared with their food-sufficient counterparts, younger adults (aged 20-59 y) from FIF had lower intakes of calcium and were more likely to have calcium and vitamin E intakes below 50% of the recommended amounts on a given day. Younger adults from FIF also reported lower 1-mo frequency of consumption of milk/milk products, fruits/fruit juices and vegetables. In addition, younger adults from FIF had lower serum concentrations of total cholesterol, vitamin A and three carotenoids (alpha-carotene, beta-cryptoxanthin and lutein/zeaxanthin). Older adults (aged > or =60 y) from FIF had lower intakes of energy, vitamin B-6, magnesium, iron and zinc and were more likely to have iron and zinc intakes below 50% of the recommended amount on a given day. Older adults from FIF also had lower serum concentrations of high-density lipoprotein cholesterol, albumin, vitamin A, beta-cryptoxanthin and vitamin E. Both younger and older adults from FIF were more likely to have very low serum albumin (<35 g/L) than were adults from FSF. Our findings show that adults from FIF have diets that may compromise their health.