It seems pretty obvious that eating has something to do with our wellness.  Without eating, we starve to death.  But for something so obvious, eating is filled with conflict, controversy and confusion in our culture. 
   Starting from a strictly biological, physiological standpoint, eating food is important, of course, because it is the source of all our energy and resources for the growth, maintenance and healing of the body.  We need all three of the macronutrient categories - protein, fat and carbohydrates.  We need the micronutrients - vitamins, minerals and phytochemicals. And we need water.  A lack in any of these categories has a range of impacts, from a lessening of efficiency of the body's normal operations to a full-blown deficiency disease. 
   After that, it's a bit less clear.  The question of how much, what kind, what proportion comes up and everyone and their brother has a different idea and perspective with a different study or experience to back it up.  This year.  In another year it will likely change!  There are many individual factors that make a one-size-fits-all diet virtually impossible.  Your exploration into your relationship with eating and wellness is well worth the time and effort.
   There are some basic considerations about food, however, that apply in general.  First, ALL the previously mentioned macro- and micro-nutrients are essential and food is the preferred source for them - not a multi-vitamin pill.  You will never be able to overcome poor dietary choices with a vitamin.
   Second, the closer a food is to its natural state, the better for our health it tends to be - i.e., an apple is better than Apple Jacks cereal.  This also tends to minimize the chemical additives, dyes, preservatives and other mysteries that are loaded in processed foods.  Organic foods eliminate pesticides, antibiotics and hormone exposure, as well as irradiated and genetically modified foods. 
   Wellness and eating are about more than the actual food you take in, however.  Eating has a large emotional component for most people.  This started in our very first meals, as we found the comfort, security and love - or not - from our mothers.  The association of being fed and being cared for comes early and strong.  Later in life, this association will contribute to our habits of eating when under stress, for comfort, security, companionship.  Food is also used to relieve boredom and pain - both physical and emotional.  We can see this in anorexia and bulemia, and there is a significant correlation between obesity and a history of sexual abuse.  Food can be a master insulator from a variety of unwelcome feelings.
   There is a strong social component to eating.  Most celebrations, family and social gatherings, even business meetings revolve around food.  In a larger social context, the food choices we make have an impact on farmers and animals and migrant workers and the earth.  With our general movement away from family and local farming, there are many hands involved in getting food to our tables. 
   Between the government USDA & FDA and the researchers and the diet book & program gurus and the food and drink business  marketing and the animal rights people and the CSA promoters and your doctor and your brother-in-law's 2nd cousin who has the perfect answer - how do you REALLY know what eating and wellness looks like?  That answer is going to be different for each of us - and it starts with getting to know all about YOUR relationship with food.  If you have specific health issues related to foods (like diabetes or Celiac's disease), be sure to start with good medical attention.  Start paying attention - keep a journal - and notice what and where and when you eat (and drink), and with whom, and what your mood was when you began eating and when you finished, and what physical things are happening - like headaches, stomach upset, reflux, stuffy nose, joint pain and energy levels - immediately and for a day or two after different foods.  Start reading labels and maximizing whole, unprocessed foods in your diet.  Start having mealtime be an event on its own - eating with awareness and gratitude, rather than obliviously while you're also watching the news, driving to an appointment or fighting with your kids.  Trust that your body will tell you about your relationship with food and wellness if you slow down and listen to it closely. 
   Consider growing some of your own food.  Many vegetables are simple to grow in not too much space.  Even a pot of herbs on the kitchen window sill can play a fun part of your eating relationship!
   Having a healthy pattern of eating contributes to our physical health surely, but plays an important role in our emotional and social health too.  Let it be a joyful relationship!

There are many on-line resources for journaling about food and habits.    If you're interested, here are a couple to try:
Fit Day
My Fitness Pal