When deciding whether to eat a certain food or not consider where it stands on the spectrum of good and bad and make choices on that basis. Why I say this is that there is no such thing as the perfect food, or ingredient or supplement. They all have their pros and cons. You just need to be as aware of those pros and cons as possible and make choices on that basis.
So for people who eat meat they may choose the meat from grass-fed animals over factory farmed animals. Some people may choose organic produce over non-organic. Despite being arguably more healthy, both of these have cons of being more expensive. However choosing a cheaper meat or vegetable might be allow you to buy more, and if you have a family to feed that can become an important choice.
All that may sound common sense, so why do I say it?
My first point is that, as anyone who is ceoliac knows foods that contain gluten must be totally avoided. To address my own health issues I went through a totally exhaustive elimination program that at its heart took six months. Thus I know very precisely what foods I can eat and what foods will potentially harm me. Not everyone is so lucky. Yes, going through that six month process was pretty tough, I consider it the hardest battle of my life. But the result is safety in knowing exactly what I must not eat, or consume in very limited quantities. So for example, no matter how much someone says "this tomato fresh of the tomato plant is possibly the best I have ever tasted," that holds no inducement for me to eat one.
My second point is that we live in an Internet age where lots and lots nutrition research is easily accessible (including on this forum). Sadly much of that research can be confusing and contradictory. However there are common threads everyone should be aware of who has health issues. For instance avoiding processed foods except on rare occasions is a no-brainer, in my mind. This means avoiding cheap chocolates and cakes with very attractive packaging and pricing near the supermarket checkout. Not easy to avoid when you are feeling low.
But at the very least you should become as informed as you can. Then when you are in a mindset to make better choices you will be able to make them with more confidence.
Just being a member of this forum is one of those choices you have made, so you are obviously off to a head start.
But, for me at least and hopefully for you, this is a lifetime journey. Educating yourself about better health choices is not something you did last week and that's that. It is about continually picking up ideas and testing them on your body in your own time at your own pace.
Finally is it about not accepting what others say (including myself, your doctor, your dietitian, government, nutritionist, food website, research paper etc) just because they sound informed, authoritative etc. It is about learning to look critically at any advice anyone gives about food.
This is not an easy road. There are many untruths out there, many opinions biased for commercial reasons. Build up your knowledge about yourself. Learn to listen to your body. Treat it with respect and when it is damaged by illness it can heal itself, even life threatening illnesses. No this is not an easy road, but it is the best road. Every other road leads to poorer health.
Tips and good food eat 
Is the food you eat healthy？
Healthy Eating With Severe Food Allergies
10 foods you should never eat
