I'm a bit of a follower of Patrick Holford, but have not read this particular book. Perhaps the word "high" might be overselling the effects of the supplements a bit. Also, it highlights the fact that everyone is different, so the supplements mentioned in the book might not work for everyone.

Taking supplements to fix a particular problem, or achieve a particular effect, can be a bit hit-and-miss. For example, taking tryptophan for sleep or mood would only work if a tryptophan deficiency was your problem. If the issue was actually caused by something else, a different supplemt or other approach might be required.

The only major criticism I have of Patrick Holford is that he sells his own supplements. This makes him biased in favour of reporting the positive effects of products he earns money from. This is why I like the nutrition expert Andrew Saul, because he refuses to sell his own supplements or even recommend any specific brands. He'll recommend what nutrients you need to take, but won't say where to buy them. This indicates a higher level of integrity.