Organic acid test (OAT) has gained popularity among many functional health experts in recent years. In this article, we will go over the detoxification markers and oxalate metabolism markers and check whether there’s enough research to support their use.
What is the Organic Acid Test?
Organic Acid Test, popularly known as OAT, measures the levels of organic compounds in urine that are produced in the body as a part of many vital biochemical pathways. It’s used to check for RARE inborn genetic defects of metabolism, most often in newborns.
A defect in a particular pathway can result in either accumulation or lowered levels of its byproducts. Thus, measuring the levels of these markers can help to identify which metabolic process is blocked or compromised.
However, OAT has been increasingly available as a pricy, direct-to-consumer test recommended by many alternative practitioners. In this article, we will break down the science behind testing for detoxification markers and oxalate metabolism markers. One of these tests is more useful than the others. Read on to find out more.
Detoxification Markers
According to OAT proponents, low is good for detoxification markers. Higher levels indicate there’s toxic exposure and/or increased oxidative stress.
1) 2-Methylhippuric Acid
Methylhippuric acid (2-methylhippurate) has been used as a marker of xylene exposure [1, 2, 3].
Common sources for xylene exposure are paint thinners, building products, fuel, exhaust fumes, and industrial solvents.
Unless you are exposed to xylene at work, this test will likely be of limited benefit to you.
2) Orotic Acid
Orotic acid is produced in the body as an intermediate compound in pyrimidine metabolism. Levels increase in many inborn errors of the urea cycle, when there is excess ammonia (hyperammonemia). It also increases in a number of other disorders involving arginine metabolism [4, 5].
High orotic acid levels can be caused by:
- Arginine deficiency [3, 4, 6]
- Refeeding after fasting [7]
- Impaired liver function due to alcohol, drugs (such as valproic acid), liver disease or viral liver infection [8, 5, 9, 10, 11, 12]
- Physical trauma [13]
- Inborn errors of urea cycle metabolism [4, 14]
If your levels are abnormal, work with your doctor to find out what’s going on in order to properly treat the underlying condition.
3) Glucaric Acid
Urinary glucaric acid levels indicate overall liver detoxification status.
Elevated levels suggest exposure to:
- Pesticides [15]
- Herbicides [16]
- Solvents [17]
- Petrochemicals, e.g. toluene [18]
- Alcohol, in alcoholism [19, 20]
- Medication, including professional exposure to drugs such as anesthetics [21, 22, 23, 24]
It’s unknown whether testing glucaric acid has any benefits over regular, reliable, and well-researched liver function tests.
4) 2-Hydroxyhippuric Acid
Salicyluric acid (also called 2-Hydroxyhippuric acid) is formed in the body as it eliminates excess salicylates, such as aspirin [25].
People who take aspirin have elevated salicyluric acid [25].
Slightly more salicyluric acid is excreted in the urine of vegetarians than in non-vegetarians, consistent with the observation that fruits and vegetables are important sources of dietary salicylates. However, these levels are nowhere near as high as the levels seen in people taking aspirin [25].
We can’t think of any benefit to using this marker, except possibly for doctors to check for an overdose.
5) Pyroglutamic Acid
Pyroglutamic acid, also called 5-oxoproline, is a metabolite of glutathione. High levels can signal glycine deficiency or glutathione depletion [26, 27, 28].
Vegetarians can have higher levels, due to differences in glycine metabolism [29].
Elevated levels can be seen in case of:
- Acetaminophen (Tylenol, Panadol) toxicity [30, 31]
- Glycine deficiency/insufficiency [26, 27]
- Diabetes [32]
- Burns [33]
- Heart failure [34]
- Genetic disorders [35, 36, 37, 38]
Depending on the cause of elevated levels, people may benefit from glycine or glutathione supplements.
Remember, always speak to your doctor before taking any supplements, because they may interfere with your health condition or your treatment/medications!
6) 2-Hydroxybutyric Acid
This acid, also known as α-hydroxybutyrate (AHB), is produced as a byproduct of the breakdown of sulfur-containing amino acids. Its production increases when there’s an increase in oxidative stress or in glutathione production due to higher detoxification demands [39].
Elevated levels are encountered in:
- Insulin resistance [40, 41].
- Lactic acidosis and ketoacidosis [42, 43, 44]
- Inherited metabolic disorders [45, 46]
Studies suggest 2-hydroxybutyric acid may be useful as an early biomarker of insulin resistance and glucose intolerance in the nondiabetic population [40, 41]. However, larger, well-designed studies are needed to confirm this.
Oxalate Metabolism Markers
Oxalate metabolites include glyceric acid, glycolic acid, and oxalic acid. It’s good to have all of these low.
Glyceric and glycolic acids are elevated in genetic disorders (hyperoxaluria type I and II) [47].
Oxalic acid (oxalate) is elevated in:
- Excessive dietary intake of oxalate rich foods – oxalic acid and its salts (oxalates) occur in a number of plants. When these plants are eaten, oxalates get absorbed. They bind calcium and other minerals in the body and get excreted by kidneys into urine [48, 49].
- Low calcium intake, as calcium decreases oxalate absorption in the gut [50, 48]
- High vitamin C supplementation [51, 52]
- Prolonged antibiotics use [53]
- Ethylene glycol poisoning [54]
- Rare genetic disorders [47]
Vegetarians who consume greater amounts of vegetables will generally have a higher intake of oxalates [49].
While the human body also produces some oxalic acid, high additional amounts from the diet can cause kidney stones [49].
If your oxalate metabolites are elevated, you should:
- Avoid oxalate-rich foods, such as spinach, beets, rhubarb, sweet potatoes, chocolate, and nuts [48]. Boiling and steaming foods high in oxalate will reduce their oxalate content [49, 55].
- Hydrate; dehydration promotes kidney stone formation [56]
- Replace coffee and tea with water. In regular drinkers, coffee and tea can contribute up to 80-85% of total oxalate intake [57].
- Optimize your calcium [48]. Low calcium can increase oxalate levels. Also, calcium binds oxalate it makes it less available [49].
- Make sure you’re not over-supplementing with vitamin C [51+, 52]
- Animal protein in the diet is linked with kidney stone formation. If you are suffering from kidney stones, limit the amount of protein you consume [58].
Doctors will often test oxalates in urine independently or as a part of a routine urinalysis.
Takeaway
While testing oxalate is relatively common practice, testing other “detoxification” markers is of rather limited value and unlikely to be of benefit, unless your doctor is screening for inborn metabolic disorders or you’re exposed to significant amounts of toxic chemicals in your workplace or environment.
Further Reading
To find out which parts of the OAT test make sense and which don’t, we delve into the science and look into each of the marker types in isolation:
