Runners do not need to completely avoid any foods entirely (unless they have an allergy or intolerance), however, limiting inflammatory foods such as those high in saturated fat, added sugars, sodium, and cholesterol, is encouraged to support general health and performance [ 1
Simple carbohydrates, such as white grains, juices or sweets, may be an easily digested, carbohydrate option before a run. However, in general, foods and beverages such as alcohol, fried foods, sugary drinks and sweets, should be limited in the overall diet as these are generally less nutritious and provide few essential vitamins and minerals, such as calcium, Vitamin D, zinc, iron, B-vitamins [ 1 2
For some runners, certain foods may also need to be avoided pre-run to reduce gastrointestinal (GI) distress. Runners who suffer from runner’s stomach should avoid or limit foods such as raw veggies, fruits, beans, and other fibrous foods, carbonated beverages and/or dairy products [ 3
3], in and around a running session.
Migala, J. (2021, December 7). The 15 Vitamins and Nutrients You Need for Better Running. Runner's World. https://www.runnersworld.com/nutrition-weight-loss/a20839428/the-15-nutrients-all-runners-need/
Nieman, D. C., Butler, J. V., Pollett, L. M., Dietrich, S. J., & Lutz, R. D. (1989). Nutrient intake of marathon runners. Journal of the American Dietetic Association, 89(9), 1273–1278. https://pubmed.ncbi.nlm.nih.gov/2549112/
Erdman, K. A., Jones, K. W., Madden, R. F., Gammack, N., & Parnell, J. A. (2021). Dietary Patterns in Runners with Gastrointestinal Disorders. Nutrients, 13(2), 448. https://doi.org/10.3390/nu13020448