Patient red flags that may suggest nutrient insufficiencies / metabolic dysfunction:
- Memory loss
- Mood changes – depression, anger, agitation, anxiety
- Sleep abnormalities
- Problems maintaining steady blood sugar
- Weight gain
- Increased cardiovascular disease risk
Metabolism & Cardiovascular Disease (CV)
Elevated Homocysteine, a well recognised risk factor for cardiovascular disease, has been shown to promote the build-up of plaque in the arteries leading to arteriosclerosis, myocardial infarction and stroke. This unhelpful compound can be readily converted within the body to the far more helpful amino acid Methionine via the process of transmethylation. Methionine, and subsequently S-Adenosyl-Methionine, is the body’s principle methyl donor. Methylation reactions are important in the regulation of gene expression, cell proliferation, protein synthesis and function, and also in detoxifying everyday chemicals. The enzyme that drives this conversion from homocysteine to methionine requires vitamin B12, and whilst measurements of Homocysteine directly have been used to ascertain vitamin B12 status, this methodology alone has been prone to numerous misleading factors due to the alternate fates of homocysteine. Likewise, direct serum measurements of vitamin B12 have become notoriously unreliable as a means of ensuring ‘sufficiency’ of this vital yet highly elusive vitamin. Alternatively, vitamin B12 deficiency can be very reliably assessed by measuring the organic acid, Methymalonic acid, in urine. The conversion of methylmalonyl CoA to succinyl-CoA by the enzyme methylmalonly-CoA mutase is vitamin B12 dependant. This pathway is vitally important to every cell in the body as it facilitates the entry of dietary fuel sources (e.g. from amino acid and fatty acid breakdown) into the central energy producing pathway of the body – the Citric Acid Cycle (CAC).
Therefore urine Methylmalonic acid serves as a unique and sensitive marker of vitamin B12 deficiency, which if otherwise left undetected can have a broad spectrum of metabolic/health consequences.
B12 deficiency can manifest alongside:
- Fatigue, anxiety, depression
- Seborrheic dermatitis
- Neurologic disorders: sciatic neuritis, trigeminal neuralgia, Bell’s palsy, dementia
- Megaloblastic anemia
Like methylmalonic acid, the rest of the metabolic acids measured on the US BioTek ‘Urinary Metabolic Profile’ (UMP) represent intermediate metabolites of various biochemical pathways that occur within every cell of the body. These pathways all allow the cell to carry out its vital processes for energy production, growth and repair. For these metabolic pathways to function optimally, they each require certain nutrients; vitamins, minerals and co-factors. Measuring these acids in urine therefore offers an indispensable means for assessing the utility of the nutrients involved in these enzyme pathways (and can often reveal insufficiencies even in the face of existing supplementation, whereby adjustments to doses and forms often need to be considered in order to maximise their efficacy).
The History & Nature of Measuring Metabolic Acids in Urine
Originally, this type of testing was designed to detect high levels of organic acids in the urine of infants due to inborn errors of metabolism (IEM). Such inborn errors are usually due to significant defects in various genes. The products of these genes (enzymes) do not function properly and thus cause high levels of various organic acid compounds (usually upstream from the defective enzyme) to buildup (unmetabolised) and spill into the urine in higher than normal amounts. An example of an IEM is ‘Maple Syrup Urine disease’ or branched chain ketoaciduria. The name is derived from the fact that urine with high amounts of these compounds can often be perceived to smell like maple syrup, and was therefore one of the most obvious to first be characterised.
Being a genetic disorder, it usually starts in infancy and involves a defect in the breakdown of the branched chain amino acids by the enzyme branched chain keto-acid dehydrogenase (BCKADH). BCKADH is a complex of enzymes similar to Pyruvate Dehydrogenase (conversion of pyruvate to acetyl-CoA) and a-Ketoglutarate Dehydrogenase (conversion of a-ketoglutarate to succinyl-CoA) – each of these requires a host of B vitamins to function and is intimately regulated by various minerals (such as, Mg, Ca, and K).
This demonstrates how LOW amounts of certain nutrients in the body can lead to HIGH amounts of unmetabolised by-products from certain biochemical pathways, which can then be compounded by the presence of genetic polymorphisms or toxins. These and other factors will therefore need to be considered when HIGH or IMBALANCED levels of metabolic products appear in the urine.
Therefore, beyond the very obvious and immediate impacts of inborn errors of metabolism like maple syrup urine disease, a vast array of other, more subtle, inherited and environmental factors can also be seen to be present for many individuals.
The Other Factors: Medications, Stress, Ageing…
Diminished enzyme capacity can also result from oxidative stress and ageing. Oxidative decay deforms many proteins, decreasing their affinity for their vitamin cofactors. Medications (such as H2 acid inhibitors, statins, oral contraceptives), smoking, alcohol, or poor diet, may also tax crucial metabolic pathways of the body. Patients on Statin cholesterol lowering drugs, for example; are at risk for developing symptoms of CoQ10 deficiency with chronic fatigue, depression and myopathy. Statins inhibit the enzyme HMG CoA reductase, the rate controlling enzyme of cholesterol synthesis.
The organic acid Hydroxymethylglutarate is an intermediate in this pathway which provides an offshoot in the production of CoQ (coenzyme Q10, ubiquinone). CoQ plays a central role in the electron transport chain (ETC) of the mitochondria which makes energy for the cell.
Ubiquinone collects reducing equivalents from nicotinamide adenine dinucleotide (NADH), and flavin adenine dinucleotide (FADH2) carrying enzymes and passes them along the inner membrane of the mitochondria in a series of reactions to make cellular energy. These enzymes require vitamins B3 and B2 respectively.
Hydroxymethyglutarate may therefore be elevated in patients on statin drugs or individuals with polymorphic HMG CoA reductase enzyme or oxidative damage to this enzyme from age. Furthermore, the organic acids fumarate and malate from the CAC may serve as additional markers of the need for CoQ10.
As the CAC cycle turns, reduced equivalents are generated:
- succinate – fumarate = FADH2
- malate – oxaloacetate = NADH
- isocitrate – alpha-ketoglutarate = NADH
- alpha-ketoglutarate – succinyl-CoA = NADH
Markers of Fatty Acid Oxidation
Seizures and neuromuscular problems may present with deficiencies in the dehydrogenase enzymes that are involved in oxidation and breakdown of fatty acids for energy. The nutrient Carnitine is responsible for getting fats into the mitochondria of the cell to be burned (oxidised) for energy. A deficiency in carnitine or vitamin B2 can perturb this process. As a result we can see the following organic acids elevated in the urine; adipate, suberate and ethylmalonate. Elevation of these analytes may indicate a benefit from the supplementation of carnitine and vitamin B2.
Other key organic acid/nutrient associations:
- Beta-hyroxyisovalerate and biotin
Biotin is involved in fatty acid metabolism and the breakdown of carbohydrates.
- Kynurenate and vitamin B6
Vitamin B6 has a ubiquitous role in energy metabolism, nervous system function and immune function. A deficiency can have broad spectrum consequences from carpel tunnel syndrome, rheumatism, PMS, attention deficit hyperactivity etc.
Markers of Neurotransmitter (NT) Metabolism
Dopamine and Serotonin are two of the most important NTs. Dopamine is the NT that keeps us alert and vigilant. It is responsible for our emotional drive and spontaneity. Without it we can feel dull and ‘out of sync’ with the world around us. Depression and negativity can also result. It also controls our ‘fight or flight’ response by controlling the release of noradrenaline and adrenaline, which automatically alerts us and mobilises energy in an emergency.
Serotonin is responsible for our peace of mind, tranquility and comfort. It ‘filters out’ negative impulses and behaviours. Too much serotonin can lead to nausea and diarrhea. Too little can cause a person to be anxious, restless, depressed, impulsive and aggressive. These NTs are made within the brain (‘behind’ the BBB) from the amino acids Tyrosine and Tryptophan. The responsible enzyme, aromatic amino acid decarboxylase (AAD) requires vitamin B6.
After hydroxylation of Tyrosine to form L-Dopa (which requires vitamin B3), decarboxylation by AAD forms Dopamine (via B6). Dopamine is broken down to Homovanillate (HVA), by the enzyme catechol O-methyltransferase (COMT) – (which requires vitamin B2).
Tryptophan which is first converted to 5-HTP (which requires vitamin B3 and Iron), is also decarboxylated by AAD (and therefore competes with Tyrosine for balance) to yield Serotonin, which is subsequently broken down to 5-Hydroxyindoleacetate (also requiring vitamin B2 and B6).
Low levels of these markers can therefore reveal chronic deficiencies, bottle-necks and imbalances of these NTs. Elevated levels may suggest a high turnover (with a greater demand for the precursor amino acids and vitamin cofactors).
Imbalances such as insufficiency of the enzyme AAD with increased concentrations of HVA has been noted in some autistic patients.
Vitamin B6 therapy to support AAD has been shown to be beneficial in such cases. Keep in mind that autistic individuals may harbour a variety of mutations in different metabolic enzymes not just those involved in neurotransmission and hence require additional nutrients in order to find balance; e.g. vitamin B2 for FAD enzyme processes, vitamin B3 for NAD processes, B12 and Folate for methylation processes and vitamin C to support some of the many impaired detoxification pathways that have been implicated in autism spectrum disorders.
- Quinolinate and Para-Hyroxyphenyllactate and antioxidant status (Vitamins C, E and alpha-Lipoic acid)
- Orotate, from the urea cycle, is involved in the detoxification of ammonia from protein breakdown and requires the amino acid Arginine and the mineral Magnesium.
- Pyroglutamate and Glutathione (GSH)
GSH is the most important antioxidant inside the cell. It reduces chronic inflammation in the tissues that can lead to arthritis, autoimmune diseases and cancer, it helps maintain immuno-competence (stimulates interleukin production and WBCs), and is involved in Phase II detoxification pathways in the liver. Supplementation with N-acetyl- cysteine and alpha- Lipoic acid have both been found to be highly effective in enhancing the regeneration and activity of GSH, especially during oxidative stress such as exhaustion, fighting an illness or a flu, or during intense exercise.
Metabolic acid testing in urine therefore provides a highly valuable and detailed clinical tool to aid in the nutritional work-up of any patient in order to better support their biochemical individuality and clinical needs. Polymorphic genes, oxidative damage from free radicals, age, toxic build-up or drug effects may predispose one to special nutritional needs, requiring higher amounts of various vitamins, minerals and other cofactors than might otherwise be assumed or even considered to drive any one of a number of enzyme pathways sufficiently to reduce the severity and risk for an incredibly broad range of disease and dysfunction.
Toxins: The Other Half Of The Picture
Note: It can be essential to combine any UMP with an EPP (any Urine Metabolic Acids Profile can be combined with an Environmental Pollutants Profile from the same urine sample if requested at time of processing). This provides an even more comprehensive overview of metabolic balance for an individual, identifying and ruling out one of the most insidious non-deficiency based reasons for metabolic derangement.
Conducting a UMP on its own can sometimes leave a practitioner wondering what role chemical toxins (aka endocrine disruptors) are having on any of the metabolic derangements revealed through testing. In turn an EPP conducted on its own can sometimes leave a practitioner wondering what impact any of the detected toxins might be having on cellular metabolism.
It is therefore the combination of UMP+EPP that offers one of the most comprehensive metabolic assessments clinically possible.
Ames, B.N., Ilan, E.S., Silver, E.A. (2002). High-dose vitamin therapy stimulates variant enzymes with decreased coenzyme binding affinity (increased Km): relevance to genetic disease and polymorphisms. Am J Clin Nutr, 75, 616-658. Bhagavan, N.V. 1992. Medical Biochemistry. Boston: Jones and Bartlett Publishers International.