No, eating the same things every day - especially healthy foods - won't affect you adversely, and your body won't become toxic as a result. However, it is important to vary your diet to make sure that you are covering all your nutritional bases and that you're not getting too much of any one thing. I checked with pediatrician Sandy Newmark, M.D. to see if eating the same foods daily could pose a health problem for children. He said that he had seen no research that suggested any such danger, but he agreed that a variety of foods is best, for children as well as for adults.
It may be possible, however, to develop intolerances to foods you eat often - you may find you are less able to digest them than you used to be or that you react badly to some of them. But with certain exceptions (lactose intolerance, gluten intolerance) food intolerances are highly individual and mysterious. In some cases they are triggered by physical or emotional stress or exposure to environmental toxins. Lactose intolerance stems from a deficiency of the enzyme lactase, which is needed to help digest lactose, a sugar in milk. Individuals with this problem develop bloating, abdominal pain and, often, diarrhea when they consume milk. Gluten intolerance is caused by an abnormal immune response to gluten, the major protein in wheat and some other grains. These problems have a genetic basis.
Some people react to natural substances like the histamine in foods such as cheese, some wines and certain fish, particularly tuna and mackerel. Eating a food with a high level of histamine can lead to what seems to be an allergic reaction but is really just a response to the effects of the compound, sometimes called "histamine toxicity."
I encourage you to vary your diet - include as much fresh food as possible, minimize your consumption of processed foods and fast food and eat lots of fruits and vegetables. If you follow my anti-inflammatory diet, you'll get the vitamins, minerals, essential fatty acids and dietary fiber you need for optimal health.
Andrew Weil, M.D.