Nitrogen is part of all the amino acids used to make proteins and essential for good health. As long as you eat at least 0.83 grams of protein per kilogram or 2.2 pounds of body weight per day, you'll meet your body's nitrogen needs. Nitrogen also occurs in substances called purines, which are present in many different foods and also occur naturally in the body. People with gout should limit purines in their diet, because they may make gout worse, but healthy people don't need to limit purines.
Meat and Poultry
Meat and poultry, including beef, pork, chicken, turkey, goose, duck and the organ meats of these animals, contain high amounts of protein and purines. The healthiest cuts are those that have had extra fat removed, such as skinless chicken or trimmed lean cuts of beef, including tenderloin, top sirloin and round cuts.
Fish and Seafood
You'll also get a lot of nitrogen from fish and seafood due to the high purine and protein content of these foods. Seafood choices particularly high in purines include mussels, sardines, anchovies and scallops, but crab, shrimp, lobster and oysters also contain a moderate amount of purines. The healthiest seafood options include those that are high in essential omega-3 fats, such as herring, salmon, mackerel and sardines.
Fruits and Vegetables
Legumes and soy products are the only types of vegetables that are high in protein. Some fruits and vegetables are high in purines, however, and thus contribute to your nitrogen intake. These include legumes, cauliflower, spinach, green peas and asparagus. No fruits are high in either protein or purines, so fruits aren't a good source of nitrogen.
Dairy products, eggs, nuts and seeds all provide protein, so they also provide nitrogen, although they're low-purine foods. Whole grains, including wheat and oats, also provide some purines and protein. MedlinePlus recommends choosing lowfat dairy products, watching your serving sizes of nuts and seeds due to their high fat content and limiting eggs to no more than four per week because of their high cholesterol content.