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Overview: ALDH2 Deficiency
ALDH2 Deficiency is a genetic mutation affecting over 1 billion people globally. Those with the mutation are unable to properly break down a toxin called acetaldehyde.

Overview of ALDH2 Deficiency

Three terms to understanding the problem:

1. ALDH2 ( Aldehyde Dehydrogenase 2 ) is an enzyme found in the liver. It is responsible for the breakdown of acetaldehyde. The average person with a healthy ALDH2 enzyme can quickly and safely break down acetaldehyde.

2. Acetaldehyde is a common cancer-causing toxin naturally occurring in both avoidable and unavoidable sources in everyday life.

3. ALDH2 Deficiency is a genetic disorder in which the ALDH2 enzyme is present, but inactive and unable to properly regulate acetaldehyde levels. This enzyme mutation is especially common among those of East Asian descent. Those with the mutation are at increased risk of long-term disease.

    What is Acetaldehyde?

    Acetaldehyde is Class 1 carcinogen naturally occurring in the air we breathe and many food and drinks we consume. For individuals with normal metabolism, acetaldehyde is safely broken down by an enzyme found in our liver. This enzyme is called Aldehyde Dehydrogenase 2 ( ALDH2 ).

    Deficiency in the enzyme leads to unhealthy levels of acetaldehyde that may cause serious diseases like Liver Cirrhosis, Esophageal & Gastric Cancer and Alzheimer’s Disease. ALDH2 Deficiency is a dominant genetic disorder affecting over 1 billion people globally. While ALDH2 Deficiency affects up to 40% of all people of East Asian descent, it can also affect people of other ethnicities. 

    Where Does Acetaldehyde Come From?

    • Drinking Alcohol - Drinking alcohol spikes blood acetaldehyde concentrations to very high levels for short periods of time, typically 2-4 hours. Ethanol found in alcoholic beverages is quickly converted into acetaldehyde. In those with ALDH2 Deficiency, the acetaldehyde accumulates rapidly, leading to physical symptoms known as Alcohol Flush Reaction (Commonly referred to as 'Asian Flush' or 'Asian Glow'). Acetaldehyde concentrations can be more than 10 times higher in people with ALDH2 Deficiency.
    • Smoking - Acetaldehyde is the most common toxin in cigarette smoke and is the cause of many of the negative health risks associated with cigarette smoking. When tobacco is burned, acetaldehyde is produced and enters the smoke, which is then inhaled. Individuals who smoke, or are frequently inhaling second-hand smoke, are continuously being exposed to more acetaldehyde.
    • Breathing Polluted Air - Acetaldehyde is one of the most common indoor and outdoor air pollutants. Indoor air concentrations of acetaldehyde in the home and the workplace are often even higher than outdoor concentrations. Major indoor sources of acetaldehyde in the air come from building materials, flooring, paints and treated wood. Second-hand smoke is a major contributor to indoor air acetaldehyde. Outdoors, acetaldehyde is commonly released into the air during production and transportation of the chemical. In addition, acetaldehyde is released into the air via vehicle emissions, power plants, factories, and the burning of plant or trash material.
    • Food and Diet - Fermented foods and beverages, dairy products, coffee, tea, bread, ripe fruits, and some processed foods contain varying levels of acetaldehyde. Diets high in refined sugars can lead to an increase in acetaldehyde. Yeast populations called Candida albicans live naturally in the human gut, and are usually kept in check. Candida albicans convert sugar from the diet into acetaldehyde through fermentation. A diet higher in sugars can lead to an overgrowth in Candida albicans populations, which convert more sugar into acetaldehyde in the gut. This acetaldehyde can cause damage to the gut and can eventually make its way into the body and other tissues. Use of antibiotics can also disrupt the balance of Candida albicans in the gut and lead to overgrowth.

    ALDH2 Deficiency and Disease

    Since acetaldehyde is regularly entering the body from numerous sources or being created inside the body, it is always present in low concentrations. In those with ALDH2 Deficiency, acetaldehyde accumulates and can damage DNA and proteins in the body. Long term exposure to acetaldehyde can have serious health implications, including higher risk of diseases like:

      • Gastric and Esophageal Cancer: Acetaldehyde entering the throat and GI tract from foods, alcohol, and cigarette smoke causes damage to the esophagus and stomach. More information.
      • Liver Disease: Exposure to acetaldehyde over time causes scarring in the liver that leads to liver cirrhosis and liver disease. More information.
      • Alzheimer's Disease: There has been research indicating that the increased acetaldehyde entering the brain in those with ALDH2 Deficiency causes damage to brain cells. More information. 
      • Osteoporosis: Acetaldehyde can negatively impact bone development, and recent research shows those with ALDH2 Deficiency are at a significantly increased risk of losing bone density and developing Osteoporosis. More information.

    Detecting ALDH2 Deficiency

    Symptoms of ALDH2 Deficiency are largely unnoticeable as acetaldehyde can circulate in the blood at low to medium concentrations without causing any particular symptoms. The most noticeable symptom of ALDH2 Deficiency is Alcohol Flush Reaction, a series of symptoms that occur when drinking alcohol, the most obvious of which is red flushing of the face and skin. You can also find out if you have ALDH2 Deficiency by taking a simple at-home DNA test for the ALDH2 gene.