Females (n = 28) and males (n = 39) had their plasma analysed for selenium (Se), ubiquinone, alpha-tocopherol (vitamin E), the essential fatty acid (EFA) classes: omega-3 (omega-3, n-3) and omega-6 (omega-6, n-6) fatty acids. Selenium averaged 0.99 +/- 0.03 mumol/l and was positively related to plasma ubiquinone, alpha-tocopherol and the EFA index: the omega-6/omega-3 ratio. Food supplements (nutratherapy) with the lipophilic antioxidants ubiquinone and alpha-tocopherol (Q + E) had no effect on selenium but the addition of omega-3 fatty acids as a fish oil concentrate (Q + E + n-3) had (1.12 +/- 0.05 mumol/l, + 36%, p < 0.001). (Q + E) and (Q + E + n-3) with the addition of selenium (200 micrograms or 2.5 mumol a day) raised selenium but not higher than (Q + E + n-3) itself (1.17 +/- 0.12 mumol/l, p < 0.05). After (Q + E) alone, selenium was related as at base-line to both ubiquinone and alpha-tocopherol but not to any marker for EFA. After (Q + E + n-3), selenium was only related to ubiquinone. An unsatisfactory alpha-tocopherol nutratherapy was suggested as the explanation. EFA or markers for EFA were in no situation related to plasma selenium.