These days an array of books, magazines, websites and numerous bloggers promote a variety of flakey “detox” schemes. Our pal Vani believes in a concoction made from celery, cilantro, cucumber, lemon and ginger root. Others promote “detoxing” with lemons, maple syrup and cayenne pepper. There is no mention of what “toxins” are being removed, how they are being removed or what evidence there is that they have been removed. While claims about detox “cleanses” are pure nonsense, the concept of detoxification is real. There are various ways the body deals with foreign substances with the use of cytochrome p450 enzymes being a classic example.
The “p” in the name of this family of enzymes refers to “pigment” and 450 refers to the specific wavelength of light used to spectroscopically identify these coloured (chrome) molecules that are found inside cells (cyto). A spectroscopic study involves exposing a sample to various wavelengths of light and determining which wavelengths are absorbed, a common laboratory identification technique.
Our bodies are constantly exposed to foreign substances that have to be dealt with before they can cause harm. Aromatic hydrocarbons in smoke, bacterial toxins, remnants of industrial chemicals as well as food components such as caffeine, tannins and alkaloids have to be eliminated before they engage in harmful reactions. Drugs are also viewed by the body as intruders that need to be eliminated.
Many of these substances that we collectively call “toxins” are relatively insoluble in water, and therefore present a challenge for elimination through the kidneys. The cytochrome enzymes add oxygen atoms to these molecules, increasing the ease with which they can be flushed out of the system. In some cases the addition of oxygen just makes the compound more soluble and therefore more readily excreted through the urine. In others, the oxygen atom introduces a reactive site that molecules such as glucuronic acid can latch on to. Since glucuronic acid is highly soluble, it acts as sort of a “ferry” to help eliminate compounds that it has been able to grab. Cytochrome enzymes are found mostly in the liver, the organ charged with intercepting dangerous substances before they can enter the circulation and wreak havoc with more susceptible tissues.
But these enzymes can also be looked upon as the proverbial “double-edged sword.” A drug, such as the pain-killer acetaminophen, is a candidate for detoxification as it passes through the liver. The reason such medications have to be taken every few hours is that they are constantly being removed from circulation by the cytochrome enzymes. Indeed, the reason that people have different sensitivities to drugs is a consequence of having a different profile of cytochrome p450 enzymes.
Another problem is that sometimes the oxygenated form of a compound may be more toxic than the original. For example, benzopyrene in smoke, a relatively harmless intruder is converted by cytochrome enzymes into a form that can react with and disrupt DNA. In this case, the oxygen provides a “handle” that DNA can seize.
Interaction of toxins with cytochrome p450 can raise yet another concern. Furanocoumarins, naturally occurring compounds in grapefruit juice, for example, can react with these enzymes and prevent them from carrying out other detoxicating tasks. That’s why patients are told not to take their medications with grapefruit juice. Since the enzymes are not available to eliminate the drug, it can build up and have a greater effect than intended. Certain blood pressure lowering drugs, felodipine for example, can then have the effect of decreasing the blood pressure to dangerous levels.
Finally, there is also the possibility that some substances the body perceives to be toxins can induce the formation of higher than normal levels of cytochrome enzymes in an attempt to eliminate the intruder. In the process other substances may be undesirably eliminated as well. There have been cases of organ rejection attributed to patients taking antidepressants such as St. John’s wort when they were being treated with the immunosuppressive drug cyclosporine. The increased levels of cytochrome enzymes can cause more rapid elimination of cyclosporine, resulting in organ rejection.