Many people with autism spectrum disorder (ASD) utilize vitamin and mineral supplements. Nutritional deficiencies can be corrected, metabolic issues treated, and symptoms and quality of life enhanced, as reported by a number of studies. The effectiveness of ANRC-Essentials Plus (ANRC-EP), a vitamin/mineral/micronutrient supplement developed for children and adults with autism, was evaluated in a survey of 161 persons. A 3-month randomized, double-blind, placebo-controlled study of the supplement’s predecessor was used to evaluate the results of an open-label survey. The National Survey on Treatment Effectiveness for Autism (NSTEA) Overall Benefit/Adverse Effect scale and the Parent Global Impression of Autism (PGIA) were used for these analyses. The individuals in the active group reported significantly higher mean PGIA scores than those in the placebo group effect size of 0.66 in a previous trial of this type. About 73% of respondents to the NSTEA survey ranked the Overall Benefit as moderate, good, or great, significantly higher than the NSTEA study’s findings for multivitamins, the average of 58 nutraceuticals, and the average of 28 psychiatric and epileptic drugs. Overall, the number of reported adverse effects was very small (0.25/3.0), which is on par with or slightly higher than the scores for comparable nutraceuticals and far lower than the average for 28 psychiatric and seizure drugs (0.9/3.0). Sub-analysis showed that gender, age, autism severity, food quality, self-limited diet, use of psychiatric or seizure drugs, dosage, developmental history, intellectual handicap, or seizures did not substantially alter the Overall Benefit of ANRC-EP. This suggests that many individuals with ASD, whether young or old, may benefit from ANRC-EP. The study’s retrospective character, as well as the fact that respondents were more willing to participate if they were receiving favorable benefits, are drawbacks. Positive effects on multiple symptoms were observed with ANRC-EP, and negative ones were determined to be rather minor.