A healthy adult should consume approximately 20 milligrams of the amino acid threonine for every kilogram of body weight per day. This means that the average 195.5-pound American man needs around 1,774 milligrams of threonine daily and an average 166-pound woman needs 1,508 milligrams. The only way you can get the threonine you need is through your diet. As an essential amino acid, you cannot synthesize threonine. In foods, it naturally occurs in the L-form your body requires.
Fill Up on Turkey
Turkey breast is one of the richest food sources of L-threonine, according to the U.S. Department of Agriculture. A 3-ounce serving of roasted turkey breast contains 1,090 milligrams of the amino acid, an amount that fulfills 61 percent of a man's recommended daily intake and over 72 percent of a woman's required daily consumption. To avoid excess fat, eat turkey breast without the skin and choose cooking methods such as roasting or grilling instead of frying.
Experiment With Egg White Powder
With no fat, saturated fat or cholesterol in a 2-tablespoon serving, dried egg whites can be used as a healthy alternative to whole eggs in baked goods. They're also high in protein, threonine in particular. Each cup has nearly 4,000 milligrams of threonine, and every 2 tablespoons supplies 513 milligrams, or 30 percent of the daily amount needed by a man and 34 percent of the amount recommended for a woman. Plan on using 2 tablespoons of reconstituted dried egg white powder as a substitute for three fresh egg whites.
Seek Out Soy
All forms of soy are high in L-threonine. Raw soybeans contain the most, with over 3,000 milligrams of the amino acid in each cup, well over 100 percent of the recommended daily allowance for both men and women. A 1-cup serving of roasted, unsalted soybeans -- often called soy nuts -- contains around 2,630 milligrams of threonine and 1 cup of defatted soy flour has 2,144 milligrams. To incorporate soy flour into recipes for baked goods, substitute up to one-fourth of the all-purpose flour called for with soy flour.
Go for Lean Beef
A grilled top loin boneless beef filet contains 2,244 milligrams of threonine, while a braised beef chuck steak supplies 2,142 milligrams and a cooked rib eye filet has 1,989 milligrams. Other cuts of beef are also good sources of threonine, but you should pick the leanest choices available to avoid excess fat, saturated fat and cholesterol. Opt for cuts that have less than 95 milligrams of cholesterol, 10 grams of total fat and 4.5 grams or fewer of saturated fat in every 3-ounce serving or 100 grams.