Just one anecdote on that point. I'm pre-med and I recently shadowed the director of cardiac research (a cardiac surgeon) at the big hospital/medical school in this area. He was asked point-blank by a patient, "I've been reading that with diet and exercise I might be able to reverse my heart disease. What do you think?"
The doctor's answer was, "Absolutely not."
This is one data point, so it's hardly conclusive, but coming from a doctor who (a) teaches doctors and therefore plants seeds for the next generation and (b) should be an expert on new medical treatments with his position as the director of research, it's troubling.
Meanwhile, there is a growing minority of doctors who take patients through an eating "bootcamp" where they help them take out processed foods/white-flour/high-fructose corn syrup from their diet, teach them how to shop and cook plant-based foods, etc. I saw a documentary on it, "Forks Over Knives" I believe. Fascinating stuff.
In the documentary, they take a man with advanced heart disease, cut out all meat/dairy/processed foods from his diet, and take before-and-after blood readings (cholesterol, blood pressure, etc.). It was surprising how quickly the intervention reversed his numbers.
There are other pioneers working in this area. There's Dr. Terry Wahls, an MD who reversed her multiple sclerosis by eating what some would call a "paleo" diet (only vegetables, fruits, nuts, meat). Here's her TED talk if you're interested: http://www.youtube.com/watch?v=KLjgBLwH3Wc She's currently working on human clinical trials to test this diet-intervention in other patients.
To your point, "all doctors say eat better, etc." I have two thoughts.
1. I'm glad you have doctors who have mentioned that but I've never had that experience.
2. A doctor who says, "You really need to eat better," is not quite what we need. For reversible conditions like heart disease, diabetes, (MS?) etc we need doctors who say, "Your next appointment will be with a food specialist/nutritionist. He will help you completely change your eating habits, go shopping with you to get new staple-foods, and you will stick to this new lifestyle for x months. Here's a list of foods you must not eat and here are x great-tasting recipes that are easy to make. Come back in 6 weeks and we'll do another round of blood-tests to see how it's working. If you're not willing to do this I can give you [statins, etc. fill-in-the-drug] but they won't actually treat the disease and may not make you feel better. They will keep you alive though. It's totally up to you and I'll support you in either decision."
Just my 2 cents. I think medicine will eventually look more and more like this, but it will take time to change the culture and the traditions of western medicine.