Honestly there are too many ingredients for me to pinpoint any one nutrient as the "cause" and at the end of the day I took a holistic approach.
Allopathic medicine (ie modern medicine) simply looks at treating symptoms. They are always chasing their tails and many of the prescribed treatments just mask symptoms and often create different problems while ignoring the underlying issues that cause the problem to begin with.
The holistic approach is to not worry about the specific symptoms but treat the whole. What I mean by this is you cant make a cake if your missing ingredients. You cant build a house if your missing materials and you cant support proper human anatomical function if you are not getting all the micronutrients your body needs.
Sure you can bake a cake with half as much sugar or flour. You can build a house if your missing finishing nails for the moulding but would have to use something else resulting in less than an ideal finished product.
Your body has an amazing ability to "make due" in times of "drought" where certain nutrients may be lacking but it can not do so forever, sooner or later the shortages MUST be made up for if complete and proper function is to ever be restored.
The problem we face is multi faceted. The quality of our food sources declines every year as the soil becomes depleted of minerals. We are inundated with toxins which damage nutrients within the body and lastly a medical system and government that have long lost the idea that we as humans have varying nutritional needs and fail to admit that lack of essential nutrients can cause real and insideous health problems. Ever since humans gained the ability to synthesize and PATENT drugs the "need" for nutrients was swept under the rug.
There is no money in a healthy community!!
So, long story longer in addition to low T, fatigue, mental fog, depression, afib and other heart issues all happening while avidly lifting and forcing myself to get into the gym mind you, I got tired of "modern medicine" wanting to just throw meds at me.
I started researching for hours a day the role every nutrient played and the chance that the FDA and their RDA was flawed in many aspects.
I started by logging my food intake and taking a closer look at the micro-nutrients provided. Explored various sources of info, anecdotal and otherwise, of people needing and using MORE of any given nutrient than the RDA recommended dose.
It quickly because clear that my diet was not providing me even the often understated RDA requirements of many nutrients and even if it did many scientific articles have shown athletes have often much higher requirements of many nutrients.
I slowly began to add various supplements to my daily intake regiment. Some provided fairly noticeable and drastic benefits, others not so much but as the months went by my brain fog lifted, my depression passed, energy levels rose and performance in the gym increased noticeably.
All in all I am much healthier and have much better performance in my late 40's than I did in my late 30's. I have also guided other friends and family and have seen them make significant changes in their health as well.
Once you have made sure your body has what it needs then its time to revisit your nagging problems, if any still remain and if they do take a closer look at them and then and only then medication may be required but I think its pure folly to ignore the fact your body simply will not function optimally if it doesnt have what it needs to do so and no amount of drugs will replace the nutritional building blocks.
Feel free to pm me if you have any specific questions.