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Metabolomics Testing In Clinical Practice

Metabolomics

Personalised precision medicine is an exciting approach to disease prevention and management that takes into account an individual’s environment, lifestyle, and genetics. Metabolomics is a valuable tool that can be included in your assessment strategy to establish your patient’s metabolic status at any given time. 

Using metabolomics testing in your practice can help you identify exactly what your patients are eating. It can give you clues about nutritional deficiencies and excesses and help to establish your patients’ risk of disease. Metabolomics testing is an important piece of the diagnostic puzzle that can help you guide your patients toward optimal health.

What Is Metabolomics?

Let’s break it down:

  • Metabolomics is the study of the chemical pathways within the body that involves metabolites, the substrates and products of metabolism. 
  • The complete set of metabolites is known as the metabolome – a term that was coined in 1998.
  • When you do a metabolomics test, the results will give you a snapshot of your patient’s metabolic status at that time. 

Although the concept of metabolomics is relatively new, physicians have been testing for metabolites to identify inborn errors in metabolism for a long time. The old technology identified certain markers in order to diagnose a medical condition or an error in metabolism that needs to be managed. The new technology looks at a much larger portion of the metabolite set so that people get a good idea of their current health status.

Combined with a GI-Map test to assess the functioning of the gastrointestinal system and the gut microbiome, and a genomic test to assess genetic markers for disease, metabolomics testing completes the puzzle of a full health assessment.

Metabolomics Testing And Dietary Intake

The results obtained from a metabolomics test provide insight into what your patient is eating. Certain metabolites correlate with the intake of specific foods. FooDB is a database that lists which foods produce each metabolite. Here are some examples:

  • Hydroxyproline: soy products, poultry, processed meat, red meat, peanuts and wheat
  • Glutamic acid: citrus fruit and juice, sugar-sweetened beverages, soybeans, carob and almonds
  • Leucine, Isoleucine and Valine: Milk, fermented soy products, red meat, beer
  • Lysine: milk, almond milk, rice milk, red meat, fermented soy products
  • Cystine: beef, chicken, fish, whole grains, lentils, chickpeas, oatmeal, eggs, low-fat yoghurt, sunflower seeds, cheese, allium and cruciferous vegetables

Different diet styles are also associated with different metabolites:

  • The predominant metabolomic markers in someone who eats a vegetarian diet are:
    • p-Hydroxyphenylacetate
    • Phenylacetylglutamine
    • Citric acid
  • In someone following the ketogenic diet you will find:
    • Β-hydroxybutyric acid
    • Tryptophan
    • Citrulline
    • Sphingolipids
  • The Mediterranean Diet is associated with:
    • Carbohydrates: Β-hydroxybutyric acid, citric acid, cis-aconitic acid
    • Creatine
    • Amino acids: proline, glycine, branched-chain amino acids and derived metabolites
    • Lipids: oleic and suberic acids
    • Microbial metabolites: Phenylacetylglutamine and p-cresol

A study that examined the link between the Mediterranean diet, the metabolome and cardiovascular risk found that a person’s metabolic signature correlates to their adherence to the diet. It can also predict future cardiovascular risk. 

The Impact Of Nutrient Deficiency And Excess On Metabolomics

You no longer have to rely on a patient’s ability to recall what they eat in order to assess their dietary intake. Organic acid tests provide some of the information you need to give someone specific dietary advice. Metabolomics tests give a much more detailed picture of the nutrients your patient may be deficient in and those they are consuming in excess.

You may be familiar with the organic acid Formiminoglutamic Acid, being a marker for folate deficiency. It is useful but it provides only a partial picture. Studies have shown that urinary histidine excretion is three times higher than normal in people who are folate deficient.

If someone eats a lot of a certain type of food you are going to find raised levels of the metabolites that occur when these foods are metabolised. For example, someone who eats a lot of brightly coloured fruit and vegetables will excrete a high amount of polyphenol metabolites in their urine. Levels of sulforaphane, hippuric acid, equol (genistein and daidzein) and 4-hydroxybenzoic acid will be high.

Similarly, a vegetarian who eats large amounts of soy and soy products such as tofu, soy milk, tempeh and miso, will have higher than normal levels of isoflavone microbial metabolites in their urine: Equol. 

Identifying Disease Risk Using Metabolomics Testing

There is a significant amount of research on the relationship between metabolites and disease risk. A meta-analysis published in the Journal of Clinical Endocrinology and Metabolism in 2020 found an association between the following markers and type 2 diabetes:

  • Branched chain amino acids: isoleucine, leucine and valine
  • Aromatic amino acids: tyrosine, phenylalanine and glutamate
  • Alanine
  • Palmitic acid
  • Linoleic acid

It has been shown that an elevated blood concentration of the branched-chain amino acids can be seen up to twelve years before the onset of diabetes. The risk of developing type 2 diabetes is increased fourfold in people who present with these markers.

Other biomarkers that have been linked to disease risk include:

  • 2-Hydroxybutyric acid has been associated with the development of insulin resistance
  • Low glycine levels indicate an increased risk of prediabetes, type 2 diabetes, obesity, insulin resistance and glucose intolerance
  • A higher kynurenine:tryptophan ratio has been associated with an increased risk of type 2 diabetes, obesity, inflammation, renal failure, cancer, reduced cognition and cardiovascular disease.

Metabolomics Testing In Precision Medicine

The results from a metabolomics test provide greater detail of your patient’s metabolic status at any given time. They give you information about chemical pathways that are affected by what your patient does, or doesn’t eat, allowing you to make personalised recommendations that, if your patient adheres to them, may prevent the onset of conditions such as insulin resistance, type 2 diabetes and cardiovascular disease. Including metabolomics testing in your practice helps to complete your patient assessment puzzle, so that you have more information to work with to make an accurate diagnosis and offer personalised advice.