We can choose carbohydrate-rich plant foods over animal foods to boost tryptophan levels, but ideally, it would be more than just carbs. Since the main determinant of brain serotonin concentrations appears to be the ratio of tryptophan with others that compete with it for uptake into the brain, to maximize the mood-elevating effects of diet, one would ideally choose a snack with a high tryptophan-to-total protein ratio—which would mean primarily seeds, such as sesame, sunflower, pumpkin.

“Protein-source tryptophan as an efficacious treatment for social anxiety disorder: a pilot study.” So, what protein source did they use? Butternut squash seeds, because of their high tryptophan-to-protein ratio, as part of a randomized, double-blind, placebo-controlled, crossover study of people suffering from social phobia, also known as social anxiety disorder. And, they found significant improvement in multiple objective measures of anxiety in those eating the squash seed bars.

Before studies like this one, “a change in the composition of intact dietary protein was not seen as a possible option for the treatment of common psychological disorders associated with low serotonin levels.” But, that’s because they were using animal proteins (which can make things worse), not plants.

If this is true, then those eating vegetarian should be golden. And, indeed, this was the reasoning used to explain why “Global mood…was significantly better in the ‘vegetarian’ than in the ‘mixed’ diet group.” It’s all about carbohydrates, and a huge tryptophan-to-protein ratio. “The vegetarian group was instructed to avoid meat, fish, and poultry and to restrict intake of milk, milk products and eggs to a minimum…” And, within three weeks, the vegetarian diet groups had a significantly improved global mood.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Kerry Skinner.

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