It's supposed to be the ratio that matters more than the actual numbers. My cholesterol is very low in both numbers and always has been. My ratio is also "too low". I was very ill and obese for many years and it was one of the things they checked a lot. I also have very low blood pressure, so they thought I was some kind of mutant to be so fat with none of the common test results.
Once I lost "half my size" by numerous lifestyle and food changes, all my numbers stayed in the good ranges and my health rebounded like crazy. None of my doctors thought my new-found healthy eating had anything to do with it and so I stopped going to see then and stopped taking all their rx meds.
Six years later - here I still am and pretty much healthy and happy even though I still have some chronic, genetic conditions.
My son is vegetarian and makes a huge effort to get his protein. Many vegan/vegetarians I come across in diet groups do not make this effort and so are weak and sickly with no energy after being on this diet for a long periods of time. I find a lot of those people eating pasta, fruit, soy, etc and not getting enough variety in their diets. It can be done but it's not easy. Add the poison in a lot of processed foods of all types and it's a minefield.
I'm on the AIP/Paleo plan which is for fighting autoimmune disease and is heavy in bone broth, organ meat and gelatin along with veggies. Low on fruit, sugar, and other carbs. It works for me and others with my chronic problems, but it is not for everyone.
My advice to anyone on any diet is to get yourself on a nutrition tracker for a week or a month and see what you are getting into your system. There are some things hard to come by if you don't eat meat, or won't eat certain veggies, but it can be done. In my example, I have to make sure to get enough vitamin C and I'm sure to do that daily. If I don't think about it, I won't get it.
I most definitely run into depressed vegans, but I had not connected it to the food. Very interesting and I will pay more attention in the future :)