The Vegan Trap
Here’s the reason I believe this happened, courtesy of Steve Fowkes (click here to listen to the Bulletproof Radio episode with Steve Fowkes), a friend and one of the wisest biochemists I’ve ever known, and author of Smart Drugs & Nutrients II, one of the “bibles” of cognitive enhancement. Steve writes: (bolding is mine)
Unfortunately, the benefits to consuming a PUFA-containing product do not counteract the rancid-oil exposure. Furthermore, the non-rancid PUFAs deposit in the fatty tissues and cell membranes of the body where they become targets for oxygen free radicals. This is the bad side. The good side is that the PUFAs promote membrane fluidity and membrane permeability, which has a pro-metabolic effect that is in some ways similar to that generated by thyroid hormone, progesterone, exercise, vitamin D, vitamin A (not beta-carotene), magnesium and selenium (and other agents). But because it mimics the effects of these other agents, there can be perceived benefits that are not truly biologically sustainable. In other words, there is a perceived health change for the better, but I believe a vegan diet contributed to his rapid decline.
•	Higher protein intake has consistently shown to produce better training adaptations.(2)(3)(short term* vegan diets – but the long term effects hurt his performance, and then his body. I noticed this with my own vegan and vegetarian experiments. The first 3 months, you’re on fire. Then things start to break, including your brain. I’ve heard this countless times from coaching clients and people who attend my SVHI.com meetings. The sad thing is that the most competitive, hardest working people who try vegan diets tend to stick with them the longest, for the simple reason that they remember how good the first 3 months felt. When their performance – and then health – decline, they convince themselves that it couldn’t be the vegan diet, because of how good it made them feel. So they suffer while they try to figure out all the other reasons their quality of life is gradually declining, but they do not make the connection.I call this the vegan trap – it’s a naturally occurring phenomena that takes advantage of the fact that behavior changes we stick to for 40 days (or 6 weeks) tend to become permanent, and the unfortunate fact that what is a fundamentally unhealthy diet makes you feel good for a time longer than 40 days. It’s the same psychological mechanism behind drug addiction.We don’t know with certainty exactly why Carl Lewis’ performance began to decline. Maybe it was age, loss of enthusiasm, or simply better competition. However, there is good reason to believe a vegan diet contributed to his rapid decline. 
•	Higher protein intake has consistently shown to produce better training adaptations.(2)(3)(4) A vegan diet isn’t zero protein, but it almost always ends up being deficient.(5) 
•	Vegans and vegetarian are likely to be anemic and “have lower mean muscle creatine concentrations than do omnivores, and this may affect supramaximal exercise performance.” Both of these things are going to impair athletic performance, and in the case of the latter, especially sprint performance.(6) 
•	A vegetarian diet decreases muscle carnosine stores which are needed for optimal sprinting performance.(7) 
•	80% of long term vegans are deficient in vitamin B12, which is needed for proper mental function.(8) B12 deficiency causes dementia, cognitive impairment, depression, and degenerative mental disorders.(9) None of these are going to improve your sports performance.
So when it comes to the vegan diet, “Just Say No.” And remember that eating grass-fed meat kills far FEWER animals than a vegan grain-based diet, because there are no “tractor kills” in grass-fed agriculture. Behind every vegan hot dog are dozens of fuzzy mice, cute bunnies, turtles, snakes, and bugs that were mowed down by tractors and farm equipment. A diet high in healthy fats like the Bulletproof Diet only kills about 0.7 animals a year, including agriculture-related deaths, and it makes you healthier, stronger, smarter and happier and it will enable anyone to do more in the world.
Treating hormone imbalances requires a whole-body approach; the best approaches are often preventive and involve diet, exercise and other lifestyle-based strategies, as Dr. Hertoghe discusses. For instance, both estrogen and progesterone are necessary in the female cycle, and their balance is key for optimal health. Many premenopausal women have an imbalance of these hormones. If you have insufficient levels of progesterone to counter excessive estrogen, this imbalance can be further exacerbated by chronic stress. Therefore, your answer might not necessarily lie in taking hormones, but rather addressing your stress levels so that your body can normalize your hormone levels naturally.
A healthful diet, low in processed foods (which are high in health-harming sugars/fructose, grains, genetically engineered ingredients, trans fats, processed salt, and other chemical additives) and high in whole organic foods, along with regular exercise, can also go a long way to keeping your hormones balanced as you age. 
It's important to realize that processed foods—all those refined carbohydrates, and processed and heated fats, all serve to raise your estrogen to abnormal levels—as much as twice the normal, which are maintained for the better part of the adult lives of most American women. This is a MAJOR contributing cause of menopausal symptoms in the first place. Processed foods also decrease a number of other hormones critical to your health and wellbeing. Here's a quick list of Dr. Hertoghe's dietary recommendations to maintain healthy hormone levels:
Eat a Paleolithic diet, rich in fresh organic vegetables and fermented foods 	Avoid sugar and fructose, including fresh fruit juice, as the rapid sugar peak effectively blocks hormone secretion	
Eat low-fructose fruits, and avoid ones that are high in fructose	Avoid regular alcohol consumption, as this decreases your growth hormone production	
Avoid unsprouted grains. If consuming grains (which are best avoided altogether), make sure they're sprouted	Eat high-quality protein such as fish, red meat, and chicken, but cook them at a lower temperature