Dopamine, norepinephrine and epinephrine -- the latter commonly known as adrenaline -- are collectively termed catecholamines. Dopamine and norepinephrine act as neurotransmitters in the brain and nervous system, and each has a distinct function. Norepinephrine is released in response to fright, exercise, cold and low levels of blood glucose, and it increases both blood pressure and the breakdown of stored fats. Dopamine has many functions in the brain, including sleep, memory, attention and learning. Both are synthesized from tyrosine, an amino acid derived from phenylalanine, which is essential to the diet. Foods that contain the catecholamine precursors, phenylalanine and tyrosine maintain healthy levels of these important neurotransmitters.
Animal Products
Animal products are among the best sources of dietary tyrosine. Per 100 g, egg white contains 3 g of tyrosine, while whole egg contains 2 g per 100 g. Cheese is also a good source of the non-essential amino acid, tyrosine. Varieties that include blue, brick and brie contain 1 g per 100 g serving, while Parmesan cheese contains 2 g. Cod is another good source, containing 2 g per 100 g.
Other Tyrosine Foods
Other sources of tyrosine that aren't animal products include soy-protein isolate and soy-protein concentrate, whole grains, wheat and oats, and fruits such as avocado and bananas. If you're looking to increase your intake of tyrosine, choose from a variety of legumes, seeds and nuts. Almonds, lima beans, sesame seeds and pumpkin seeds are all high in tyrosine.
Phenylalanine
Phenylalanine is an essential amino acid that a person cannot synthesize and so must obtain in the diet. Your body converts phenylalanine into tyrosine. The recommended-daily intake is 1,000 mg. Foods rich in phenylalanine include many of the sources of tyrosine, which include eggs, cheese and fish. Nuts are also rich in phenylalanine. In fact, a 20 g-serving of peanut butter contains 1,290 mg phenylalanine, which exceeds the requirement. There are no health risks associated with consuming amounts above the recommended intake.
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