Yes it can. Do you drink a lot of soda? If you do, cut it all out. People who drink lots of soda can get bad nausea.
Why don't you do a test, and eat really healthy for one week, and see how you feel at the end of the week? I'm sure you will feel much better!
Good luck!
Yes, Nausea can be caused by poor nutrition. Some foods will increase the risk for nausea if you have too much of it. Much like if you eat the same food for about an hour, you'll wind up sick of the taste, right? Well, your stomach does the same. If it has too much poor nutrition, it will upset itself.
If you want to fix it, try finding out what foods make you the most nauseous primarily and then slowly work those out of your diet, or moderate them. And try to add in food that's a bit better for you. Don't make the instant jump - your stomach is used to things the way they are now and a sudden change can make you ill. But working your way back is the best thing.
