My complaint about these studies is that they are all statistic-based. Of course, there's no other way to do them since individuals can vary greatly in their responses to different foods. Sometimes, if you read the fine print, the study involves so few people that the results are more than questionable. Unfortunately, the news media (including the vaunted NY Times) tend to publish headlines that seem to draw rock-solid conclusions but then, if you read the entire article, you find that the results are tenuous.

Often, a study finds that there are "significant" results. The general public doesn't realize that "significant", in statistics, means that there is less than 5% probability that the results are due to chance. Also, the differences between experimental and control groups can be very slight, even if (mathematically) they are significant.

To quote Mark Twain, "There are lies, damn lies, and statistics".

macOS 10.15.5, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365