For foods, herbs, supplements and diets--like pharmaceuticals--"one size does not fit all". There is a Goldilocks Effect for much of what we ingest. One of the keys to finding out if you are on the "too little" or "too much" or even the "just wrong" part of the Goldilocks Effect is to being with understanding your genes. There are two ways to learn about your genes and nutrition: first, through SNPs (Single Nucleotide Polymorphisms, or variants) or having a full genome scan which will provide the SNP information along with other DNA modifications such as: splice variants, copy number variants (CNVs which are 4.8-9.5% of genes and especially important for how food is processed), inverted gene sequences, and segmental duplication.
Once you have your DNA sequenced, the DNA doesn't change and only needs to be done once. While the DNA doesn't change, it can be modified by diet and modulated by diet and by the way that food is metabolized.
The attached articles provide a review of some of the key SNPs that can affect what you ingest.
The Mediterranean Diet is an example of "One Diet Does Not Fit All". The genetics of the people living around the Mediterranean adapted to the available foods and have thrived on this diet. Many of us also benefit from this diet, but not all of us. There are SNPs that make aspects of this diet more or less beneficial for the individual. The article by Gkouskou et al. describes some of the important variants.
The article by Gurley below discusses the origins of genetic variability and plants, including potential herb-drug interactions that could be important.
Personalized genomics and your nutrition, or "Can You 'Eat for Your Genes'" is the topic of Mullins et al. the article provides a good overview of how genetics fits into the what you feel or experience. There is an overview of some important SNPs and the potential biological effects of their variants.
Vesnina et al. provides a comprehensive overview of the 34 genes involved in eating preferences and the potential role of these SNPs in personalizing nutrition. They also note how the frequency of these SNPs vary by geography/ethnicity. Some of the differences are as much as 40-50%.
Diet and genes play an important role in the development and course of chronic-degenerative diseases. DeRenzo et al. describe the dynamics managing and personalizing nutrition with the help of SNPs to manage or help prevent chronic-degenerative diseases.