Aspartate aminotransferase is an enzyme involved in the balance of proteins (amino acids). Levels of this molecule in the body can be used as a sign of liver disease and other health problems.
People go to their doctor to get their AST tested as part of a standard panel. Almost always, the results are not scrutinized, even though we know that you can be healthier and live longer when your results lie within optimal ranges. When I used to go to doctors and tried to discuss my results, they had no clue what these meant from a health perspective. All they cared about was whether they could diagnose me with some disease.
Read more to learn more about the function of AST, its associated diseases, and how to raise and lower levels of this molecule.
What is Aspartate Aminotransferase (AST)?
Aspartate aminotransferase (AST) is a protein (enzyme) in your body that speeds up chemical reactions. This specific protein is found mostly in the liver and heart but is also present in red blood cells, muscle tissue, the pancreas, and kidneys. Small amounts of this compound can also be found in the bloodstream outside of cells [1, 2, 3].
AST speeds up a chemical reaction in cells that is essential for metabolism. This chemical reaction occurs primarily in the liver, where one of the final products (glutamate) is then sent to the kidneys to get excreted through the urine .
Additionally, higher or lower measured levels of this protein can be indicative of health problems. There are tests available that measure the levels of aspartate aminotransferase in the body, and have been shown to be a useful diagnostic tool for patients. Although AST levels are mostly used to diagnose liver disease, it can be used as a marker for other diseases as well [1, 2].
The rest of the article will elaborate on the function of this protein, how different levels of this enzyme may impact your health, and how it can serve as a marker for the disease.
Aspartate aminotransferase is one of the key enzymes involved in the aspartate (amino acid) pathway. At a macro level, this pathway impacts the overall metabolism of amino acids and fats (fatty acids). The aspartate pathway also has partial roles in detoxification (urea cycle) and glucose production (gluconeogenesis) [2, 4].
At a micro level, the direct chemical reaction that aspartate aminotransferase accelerates is the conversion of an amino acid (aspartate) and acid (alpha-ketoglutarate) to a different acid (oxaloacetate) and amino acid (glutamate). This conversion is vital for other metabolic processes such as the urea cycle, glucose generation, and glucose breakdown (glycolysis) [2, 4].
Normal AST Levels
Levels of aspartate aminotransferase are highest in the liver and the heart. This protein can also be found in your muscles and kidneys. Normal healthy levels of this protein in your blood range from 10 to 40 U/L. The upper limit slightly varies across research labs [3, 5].
Conventional doctors will look at high or low AST levels and not mention anything. Sometimes, a lab result may be in the reference range, but not actually be in the optimal range. Reference ranges are not the same as an optimal range. This is why AST even in the “normal” range can be unhealthy and indicate that certain processes in the body aren’t optimal.
There are a variety of health problems that are associated with higher than normal levels of AST, and this will be elaborated further below .
Low AST Levels
Fifty-two patients with dysfunctional kidneys (prospective study), 17 of which had low AST, received vitamin B6 supplementation for a period of 5 weeks. It restored AST levels in some of the patients with low AST and caused no changes in the patients who initially had normal AST. It was concluded that the initial low AST levels were a result of vitamin B6 deficiency .
How to Increase AST
Overall, low AST levels in the blood are normal and should not be a cause for concern. Vitamin B6 deficiency may cause low AST, and therefore supplementation may be needed.
If you are diagnosed with low AST, there are some natural supplements that may help restore AST levels. Elderly patients may be especially susceptible to low AST levels, as they are at increased risk of nutritional deficiencies. Supplementation with vitamin B6 generally increases AST in the elderly .
High AST Levels
One of the major signs of a health problem is having elevated AST levels (above 40 U/L). There are a number of conditions that can cause your AST levels to be elevated, including:
- Rhabdomyolysis: This is the process of breaking down damaged muscle, causing the release of AST from the muscles. It also causes the release of a protein (myoglobin) that is difficult for your liver to process. This results in the release of AST, leading to elevated levels in the body. This can be caused by strenuous exercise [5, 7].
- Viral and alcoholic hepatitis has been reported to be one of the key players in elevated AST in the body. The inflammation of the liver increases AST levels and activity, and significantly elevated AST levels help diagnose hepatitis. Chronic alcohol consumption can also elevate AST [5, 8].
- Fatty liver also results in increased AST levels in the body. Excess alcohol consumption and obesity are both associated with having a fatty liver .
- Age: A study of 602 healthy individuals found age-related increases of mean ALT (alanine aminotransferase) levels. This increase of ALT with age was correlated with an increase in AST. AST levels might rise with increasing age .
- Gender: Adults in a specific region of China were evaluated in a study on metabolic syndrome. Although not a direct conclusion of the study, researchers noticed that AST levels were higher in males compared to females .
- Drugs: Some drugs such as painkillers, chemotherapy drugs, and statins (reduce blood pressure) may cause increases in AST. This increase in AST is usually associated with strain on the liver caused by long-term consumption or overconsumption of the drug [11, 12, 13].
How to Lower AST
There are a number of natural supplements that may reduce AST levels in your body. Although these supplements may be useful, it is more effective to treat the underlying cause of elevated AST levels (i.e., treating liver disease). Consult with your physician before taking any supplements. The supplements are as follows:
- Licorice: The effectiveness of licorice in the non-alcoholic fatty liver disease was evaluated using 66 patients who had measured increases in AST. When supplemented with licorice for a period of 2 months, the mean AST levels amongst the patients significantly decreased. This same decrease was absent in patients who did not get treated with licorice .
- Green Tea: Eighty participants with non-alcoholic fatty liver disease were given green tea treatments over 12 weeks. At the end of this period, the patients treated with green tea showed significant reductions in AST .
- Caffeine: A study involved 177 patients with liver disease who completed a caffeine questionnaire. This allowed researchers to evaluate the relationship between liver disease and caffeine. They found that patients with greater caffeine intake had lower AST levels. Caffeine may help to reduce elevated AST levels .
- Milk thistle: Supplementation in 34 patients with hepatitis C and 51 patients with type 2 diabetes reduced AST levels. Taking milk thistle may help to reduce AST levels [17, 18, 19].
Tudca (tauroursodeoxycholic acids) is a safe, short-term treatment for the restoration of liver enzymes. In a pilot study of 23 patients with liver disease, daily doses of Tudca for 6 months restored elevated AST levels in these patients .
- Turmeric may also help reduce elevated AST levels. An experiment in rats with induced liver damage with significantly increased AST levels found that turmeric treatment for 4 days significantly reduced AST levels in these rats. Turmeric may be a useful treatment for elevated AST .
- Ganoderma lucidum (mushroom): In a study previously mentioned, mice with induced-liver injury were evaluated. The mushroom, Ganoderma lucidum, was made into a liquid extract, which was used to treat the rats. Treatment with liquid extract of the mushroom significantly decreased AST levels in the blood of the mice. This mushroom may help to reduce AST in humans as well .
- Dill: One study in hamsters with high cholesterol found that dill extract and dill pills significantly reduced levels of AST. These effects suggest that dill extract supplementation may help reduce AST levels in your body .
- Alpha lipoic acid has been shown in rats to be useful in treating non-alcoholic fatty liver disease. It helps to reduce levels of liver enzymes such as AST. Supplementation may help reduce AST in your body [25, 26].
- N-acetyl cysteine (NAC): Rats were administered with a chemical that caused liver damage, resulting in increased AST levels. Upon treatment with NAC, the AST activity in the rats returned back to normal levels. This may help reduce AST in your body .
- Curcumin and capsaicin: A group of rats with induced liver disease and elevated AST were treated with curcumin and capsaicin. These dietary supplements reduced the activity of AST in the rats and may reduce AST activity in your body too .
- Vitamin C and E: One study damaged the liver cells of rabbits to test the effectiveness of vitamins C and E as supplements for the liver. Prior, these rabbits exhibited a significantly increased activity of AST; however, treatment with vitamins C and E reduced the AST activity .
Reducing alcohol consumption and losing weight may be effective in reducing AST levels in your body. This is because reduced fat and alcohol consumption will help treat those suffering from a fatty liver, ultimately reducing AST in the body [5, 8].
Additionally, coffee consumption may also help reduce AST levels. A study of 27,793 healthy participants (survey study) found that higher intakes of coffee reduced AST levels, regardless of caffeine content .
An AST test measures the amount of the enzyme in your blood. This helps diagnose underlying diseases or conditions, especially liver disease. An AST/ALT (alanine aminotransferase) ratio or ALT/AST ratio is also commonly used for the same function, and will also be touched on.
A study analyzed the medical records of all patients with extremely elevated AST (3,000 U/L and above) during a full calendar year. The elevation was measured by an AST test. Of the 56 patients who fit in this category, 40 were found to be suffering from a type of liver disease. It is concluded extreme AST elevation is most often attributed to liver disease .
The relationship between risk factors (elevated AST) and heart disease was explored in 610 patients with varying degrees of heart disease. Of these, 350 patients with heart disease had higher mean AST levels relative to 260 healthy patients. High AST levels in the blood are biochemical markers used to predict the degree of heart disease .
The AST test is used to diagnose pregnancy complications (preterm premature rupture of membranes(PROM)). In a study, 148 women in the same phase of pregnancy were evaluated. Of these women, the 74 with PROM had elevated mean AST levels relative to the healthy individuals. Measurement of AST in vaginal fluid can be used as a reliable test for the diagnosis of PROM .
Exposure to chromium is associated with many diseases such as cancer, ulcers, and other tissue damages. Rats that were administered chromium over a period of time had increased AST activity in the blood with increased chromium exposure. It was concluded that measuring AST activity levels serves as a useful marker for exposure to chromium .
ALT/AST and AST/ALT Ratios
The ALT/AST ratio may be used as a marker for insulin resistance. A cross-sectional study of 998 non-obese and 344 obese Japanese adults found that the ALT/AST ratio is a reliable marker to predict insulin resistance in non-obese individuals .
A retrospective study analyzed the use of the AST/ALT ratio as a diagnostic marker in 252 patients with chronic liver disease. They found this ratio is a useful and reproducible way of diagnosing liver disease. Progressive liver disease is associated with an increase in the ratio (and an increase in AST) .
Irregular AST Levels?
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