Sure, start with these. Good references, too.

Perspective: Limiting Dependence on Nonrandomized Studies and Improving Randomized Trials in Human Nutrition Research: Why and How https://academic.oup.com/advances/article/9/4/367/5055939

Implausible results in human nutrition research https://www.bmj.com/content/347/bmj.f6698

His most famous paper, Why Most Published Research Findings Are False https://journals.plos.org/plosmedicine/article?id=10.1371/jo...

Here's a talk on nutrition science methods, along with a specific audience moment with Walter Willet, former head of Harvard Nutrition dept, and advocate for his questionnaires. https://www.youtube.com/watch?v=KTAbx4i8Dyg -- https://youtu.be/KTAbx4i8Dyg?t=23m40s