The animals we eat or get milk and eggs from are being fed GMO grasses and grains. This cannot be avoided just due to wind and bird droppings which has gone on for decades. I don't know when genetically modified food began, but the video produced in the early 90's, "Food, Inc." declares that our food had been changing for over fifty years and that it was being engineered to last longer. I am in my late 60's and I can remember seedless grapes and watermelons when I was a kid. They had been genetically modified to grow that way.
Personally I think corn is the main culprit but all grasses and grains are affected. After my husband and I watched the video, we went through a summer of all free-range, grass fed animals, milk and egg consumption. I even screened the farm where our eggs came from. We had more constipation, indigestion, kidney pain, UTI's and incontinence until I went back to the grocery store purchases and reduced my meat consumption to no more than two or three ounces at a time.
My husband is a corn lover had a very large growth just under one of his breasts until he stopped eating so much corn. Can't confirm corn was solely the problem but I stopped buying it and the growth reduced in size and eventually appeared to go away.
The video encourages free range, grass fed animals and natural/organically grown vegetables but GMO's were not as pervasive when that was produced. I was also getting certified, organically grown carrots but my hubs and I had more trouble with candida. I then found out organics are grown in soil that contains a genetically modified fungus. There was my answer.
I only get 2% milk in glass bottles and eggs in cardboard containers.
With all due respect I have lost faith in the medical profession that could not give me some answers to problems I was having so I researched on my own and found more relief. My PCP said that medicine changes every four or five years. I believe it is because our food supply is changing and that also affects any supplements, prescriptions and any OTC medications.
I am sorry if this is overwhelming to you. This is just my opinion from what we have gone through here.