Liver Enzymes and Detoxification

Dr. Adam McLeod, ND

The majority of the foods and medications that you consume are metabolized in the liver. The liver is an incredibly complicated organ that carries out many vital tasks required for life. In the context of detoxification there are only a few major metabolic pathways in the liver that do most of the work. The liver enzymes that gets the most attention are the Cytochrome P450 enzymes. These enzymes get their name from the wave length of light they absorb (450nm) when they are in their reduced state complexed to carbon monoxide. In the human body there are 57 identified genes that code for this class of enzymes. It is incredible that the liver is able to work with such an immense variety of compounds with only a select few metabolic pathways.

Our bodies are constantly exposed to toxins and it is not possible to completely avoid this toxic burden to our cells. There are obvious sources of toxins such as heavy metals from cosmetics, pesticides on our food and pollution in the air. Even oxygen itself will generate free radicals which directly damage DNA and impair cellular function. Cumulatively this toxic stress on our cells can have a big impact on our long term health and it is connected to a long list of chronic diseases including cancer3,4.

It is critical to be proactive about addressing this toxic concern rather than waiting until a disease manifests. We know that this stress impacts our cells and there are natural therapies that can help to reduce this toxic burden. There are a wide range of effective detoxification plans that can all be helpful to eliminate toxins and several of these will be discussed in this newsletter.

Milk thistle is a herbal remedy that has a long history of safe and effective use for supporting liver function5. When the liver becomes overwhelmed with stress of eliminating toxins, milk thistle can help to gently support the liver in this effort. There are many situations where the actual liver enzymes may not be elevated on the patients blood work but they can still benefit from this additional liver support. Even though milk thistle can be helpful to stabilize liver enzymes on blood work, elevated liver enzymes are not a requirement for using milk thistle.

Heavy metals are directly connected to the formation of cancer and the metabolic reasons for this are obvious. Not only are they damaging to our cells but our bodies lack effective mechanisms to remove them from the tissues. The liver is involved in the initial steps for the removal of heavy metals but this is often not sufficient to adequately remove them from the body. There are several tests that can be done to assess the heavy metal burden in your tissues. If the levels are determined to be high then intravenous chelation therapy can be used to effectively eliminate these chemicals from your body. Chelation physically binds to the heavy metals and the resulting product is much easier for your body to eliminate.

The proactive removal of heavy metals by chelation is more indicated as a preventative approach rather than its use as a therapy for an acute condition. The mobilization of these heavy metals is actually an inflammatory process but this effect is only temporary because with each treatment there are fewer heavy metals to eliminate. The long term consequences of chelation therapy are a lowered heavy metal burden and less chronic inflammation. The reduction of this chronic inflammation is a critical component in the prevention of chronic disease.

Some of the most commonly prescribed medications are dependent on liver metabolism to either activate the drug to a therapeutically active form or to deactivate the drug for excretion. If the activity of these liver enzymes is altered then it has potential to alter the effectiveness or safety of a given medication. It is important to point out that not all interactions are clinically significant. Just because a food or a supplement is broken down by the same liver enzyme, does not mean that it is a significant interaction. It takes professional guidance from a experienced Naturopathic physician to recognize which interactions are a legitimate concern.

A well documented interaction which can impact liver metabolism is Saint-John’s Wort. This is a herbal remedy that is commonly given for depression and it is quite effective when used properly1. In addition to treating depression it also induces the liver enzyme CYP3A4 while inhibiting CYP1A1, CYP1B1 and CYP2D62. This effect makes Saint-John’s Wort contraindicated with certain medications including several prescription anti-depressants. It’s not just herbal remedies that influence these important enzymes, even grapefruit juice will have a powerful impact on liver metabolism making it contraindicated with many prescription medications.

With all this talk about interactions it is important to remember that we can use natural therapies to safely and effectively support liver metabolism. Just because something is a inhibitor or a inducer of a pathway does not make it a bad thing. When used in the correct context this can be not only safe but extremely helpful in supporting liver function. This is why you need professional guidance when putting together a treatment plan to support liver function and detoxification.



1) Linde, Klaus, et al. “St John’s wort for depression—an overview and meta-analysis of randomised clinical trials.” Bmj 313.7052 (1996): 253-258.

2) Chaudhary, Amit, and Kristine L. Willett. “Inhibition of human cytochrome CYP1 enzymes by flavonoids of St. John’s wort.” Toxicology 217.2 (2006): 194-205.

3) Nawrot, Tim, et al. “Environmental exposure to cadmium and risk of cancer: a prospective population-based study.” The lancet oncology 7.2 (2006): 119-126.

4) Boffetta, Paolo, Nadia Jourenkova, and Per Gustavsson. “Cancer risk from occupational and environmental exposure to polycyclic aromatic hydrocarbons.” Cancer Causes & Control 8.3 (1997): 444-472.

5) Ferenci, P., et al. “Randomized controlled trial of silymarin treatment in patients with cirrhosis of the liver.” Journal of hepatology 9.1 (1989): 105-113.