Testing Urinary Neurotransmitters? Avoid the Big 5

By Allison Smith, ND – Clinical Consultant at ZRT Laboratory

Food is medicine. It’s well understood that the food we eat provides the amino acids, micronutrients (eg., vitamins and minerals) and macronutrients (proteins, fats and carbohydrates) that we need to sustain our lives. However, it may come as a surprise to know that some foods contain more than just the amino acid precursors to neurotransmitters and actually contain high levels of some neurotransmitters themselves like serotonin1and dopamine2. For some people, a diet rich in those foods that are high in neurotransmitters lends just the balance they need to feel well in lieu of psychotropic medication. As an example, someone who struggles with irritability and a low mood might try a diet rich in serotonin and vitamin B6-containing foods like bananas, walnuts and pineapples. But when you’re testing neurotransmitters in the urine, these foods in fact can cause problems with the testing.

We want to measure the neurotransmitters the body is making overall that end up in the urine (sourced from the adrenals, brain, gut, etc) and the balance (or lack of it) that exists in the body. An important variable that’s easy to control, yet can significantly and artificially increase urinary neurotransmitter levels is the food you eat. There are 5 specific foods that are known to produce the biggest shifts, creating what’s known as a false positive result.

These 5 foods will send urinary neurotransmitter levels to the moon for hours after eating them. It’s essential that patients avoid these foods the day prior to and the day of urine collection:

  • Bananas and plantains
  • Nuts (especially walnuts)
  • Nut butters
  • Pineapples
  • Avocadoes

When testing urinary neurotransmitters within four or so hours after consuming these particular foods, we see an entirely food-induced elevation in serotonin, dopamine, and 5-HIAA.2 In some cases, the elevations are so significant that they can lead to misinterpretation of the test and raise suspicion of carcinoid syndrome or pheochromocytoma. Think of it like a fasting blood sample for glucose. If you have a pancake breakfast instead of fasting and check glucose just afterward, there’s a good chance you’d be mistaken for a diabetic. Your treatment advice would be based upon a false-positive result or rather a non-fasting result instead of a fasting one. If you just can’t abstain from that banana bread with walnuts for a those couple of days around your urine test collection, please remember to mark it down on your requisition form that comes in with your sample. Identify the forbidden food and jot down what time you ate it. If it shows up in your urine sample, it’ll help with the interpretation.

A urinary neurotransmitter test is a functional test which means the interpretation can be tricky – you’re doing more than just observing highs and lows (that’s easy), you’re putting weight into the high-normals, the low-normals, the ratios, appreciating the dominance of excitatory or inhibitory neurotransmitters, assessing enzyme activity and cofactor availability in those biochemical pathways by looking at the downstream metabolites, and then trying to discern and control the factors contributing to your patient’s unique symptom constellation.

Urinary neurotransmitter testing, such as that offered by ZRT, may answer big questions. For others, it may only fill in some of the missing pieces of the puzzle. Either way, the human body’s an intricate machine. The more tools we have to assess its function, the more comprehensive the treatment options become.

Download: ZRT’s Neurotransmitter Testing Patient Handout

The original blog can be found here.


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1Feldman, J M and Lee, E M. Serotonin content of foods: effect on urinary excretion of 5-hydroxyindoleacetic acid. Am J Clin Nutr October 1985 vol. 42 no. 4 639-643.

Kema IP, Schellings AM, Meiborg G, Hoppenbrouwers CJ, Muskiet FA. Influence of a serotonin- and dopamine-rich diet on platelet serotonin content and urinary excretion of biogenic amines and their metabolites. Clin Chem. 1992 Sep;38(9):1730-6.



ZRT Labs, portraits, beaverton, oregon, 06-19-2014

Dr. Allison Smith worked in private practice focused on primary care and women’s health after completing her naturopathic degree at the National College of Naturopathic Medicine in Portland OR. Now part of ZRT’s clinical team, her focus has shifted to sharing integrative approaches to health and dissecting tough cases.