What food do people with food allergies eat to get the same nutrients they need from the foods they're allergic to? i.e. nuts, shellfish and pork?

Micronutrients: Protein, Omega fatty acids and micronutrients are nutritional advantages of the foods you have mentioned. A whole raw food multivitamin and other protein sources such as lean beef, organ meats, soy, avocado, spinach, kale can help make up the difference.

Talk to your doctor : You can still eat enough variety of other foods to get the nutrients you need. You can consult a dietician for specific details.