The skinny on “detox” diets
Once the seasonal excesses of halloween through New Year’s eve are but a faint memory, there seems to be a renewed interest in ‘detoxing.’ It’s a pretty vague concept, and those who market detox programs often refer to eliminating “environmental toxins” from the system through various dietary restrictions. A friend recently asked me to recommend a detox program for her after a season of “too much alcohol and meat,” which prompted this post about the scientific basis for such programs.
Let’s start with some basic physiology and biochemistry. Between your lungs, your GI system, your kidneys and your liver, you already have multiple–and very efficient–detox mechanisms built in. For example, these systems metabolize toxic substances like alcohol and drugs into safe by-products; neutralize and excrete ammonia–which is a toxic byproduct of the metabolism of dietary protein; sequester harmful carcinogens in the intestines; and remove heavy metals from your body. Among many other things.
Ideally, the diet should provide an adequate intake of nutrients to keep these natural detox systems working optimally: sufficient water to allow your kidneys to filter waste effectively; adequate fiber to keep waste moving expeditiously through your intestines; and adequate vitamins, minerals and phytochemicals to support liver function. Beyond this, there isn’t much scientific evidence to support the claim that specific “detox” diets–like juice fasts or herbal supplement regimens–have additional benefits for clearing the aforementioned toxins from the body any better than your body can do on its own with proper nutrition support. So what’s behind some of the claims? Here are some thoughts.
Alcohol is metabolized and ‘detoxified’ by multiple mechanisms in the liver cells. The primary mechanism for detoxification of both alcohol and most drugs is known as the Cytochrome P-450 pathway. Basically, it involves a series of chemical reactions which take toxic compounds and change them into safer metabolites that can then be excreted. A healthy liver is therefore the key to efficient natural detox. Chronic, excessive alcohol intake is a sure way to compromise liver function, as is chronically popping pills like they’re candy. So it does make sense for detox diets to promote abstaining from booze, although occasional, moderate intake is easily handled by your liver without any sort of additional support from herbs or supplements. Moderation, people. It’s all about moderation.
Many detox diets advocate eliminating meat from the diet. My guess is that there are two potentially legitimate reasons that they would suggest this. First, because most conventionally-raised food animals (cows in particular, but also certain types of farmed fish, if you can believe it) are routinely treated with antibiotics and hormones. When you eat them, you unwittingly ingest these substances. However, if you choose organically-produced meats and wild-caught seafood, these concerns should be eliminated. Another reason why these diets may advocate giving up meat is due to the natural occurrence of carcinogenic compounds called heterocyclic amines (HCAs, for short) in cooked meats–especially charred/well done ones. These compounds are known to promote certain cancers–particularly colon cancer. Relatedly, processed meats (hot dogs, sausages, bacon, some cold cuts) contain preservatives called nitrites, which are precursors to carcinogenic compounds called nitrosamines. It is believed that these factors help account for the observation that diets high in meat, particularly red meat and processed meats, are associated with higher rates of stomach, colon and pancreatic cancers.
So does this mean meat is toxic? No, not necessarily. As mentioned above, you have lots of natural detox systems in place to handle these assaults. And one of them is your GI tract. Certain insoluble fibers (like the kind found in wheat bran, for example), bind to carcinogens like HCAs in your gut, tie them up to prevent them from contacting your colon cells, and safely usher them out of your body in the feces. What’s more, some of the bacteria in your gut plays a role in detoxifying carcinogenic compounds that you’ve eaten. Which brings us to the next common detox diet recommendation, which is to load up on high-fiber fruits and vegetables and whole grains. The fiber in these foods helps your intestines do their thing: it binds carcinogens, and serves as food for the gut bacteria that help detoxify harmful substances. Not to mention that the antioxidant and phytochemical content of many fruits and vegetables helps to repair oxidative damage to cells done by pollutants and dietary toxins. These are all scientifically sound reasons to explain why most detox diets recommend focusing on fruits and vegetables.
In diets that are super meat-focused–as in, a big ol’ hunk of meat at the center of the plate 1-2 meals/day–the emphasis on meat can often crowd out other really important foods like whole grains, fruits and vegetables. Therefore, if you’re serious about reducing your exposure to dietary toxins but you choose to eat meat, here’s what I would suggest: (1) Eat less meat when you do eat meat, and choose poultry more often than beef or pork. Treat it like a garnish rather than the main event, or eat portions that take up 1/4 of your plate instead of 1/2 or more. Fill in the missing plate real estate with whole grains and vegetables. (2) Eat the best quality meat (e.g., organic) that you can afford. Go for quality over quantity when it comes to meat. (3) Avoid cured, smoked or processed red meats altogether. If you must have your bacon or hot dogs or sausages, choose brands that are nitrite-free, like Applegate Farms. Usually poultry isn’t a problem, so no need to avoid turkey cold cuts. (3) Make sure your omnivorous diet doesn’t skimp on fiber. You need it to promote efficient, natural detoxification in your gut. Aim for 14g of fiber per 1,000 calories in your diet. Or, about 20g-25g/day for women and about 38g/day for men.
As discussed above, the bacteria in your gut–otherwise known as your natural flora– play an important role in natural detoxification. Therefore, anything that kills them or flushes them out will be counterproductive from a detox perspective. This includes taking antibiotics or having a colonic/enema at your local spa. If you need antibiotics, by all means you should take them! But if you pop antibiotics every time you catch a cold (which is probably a virus anyway), you may want to think twice. And while recreational colonics/enemas are marketed as detox treatments, they may, in fact, leave you more vulnerable to toxins in the medium term. Colonies of billions of bacteria don’t just re-grow overnight, you know.
With all of this emphasis on fruits and vegetables, the detox-minded may ask, aren’t we worried about overexposure to pesticides and other chemical residues? Ah… good question. Yes, of course we’re worried. We’re especially worried when it comes to children, whose small size means that ingesting the same amount of pesticides as adults do can result in much higher levels of chemical residues in the body. If this is something you’d prefer to avoid, buy organic foods whenever possible. But organics are expensive and we’re in a recession, so I personally focus on buying organic for the fruits and vegetables that are known to contain the highest levels of pesticides. (Check out a complete ranking of the pesticide loads on common fruits and vegetables from the Environmental Working Group here.) Other foods where organic matters a lot include butter and milk. And if you cannot access organic produce at all, don’t use that as an excuse not to eat copious amounts of fruits and vegetables. From what the research shows, the health-protective benefits of diets rich in fruits and vegetables outweigh the potential risks from ingestion of whatever pesticides you get in the process.
OK. So we’ve covered alcohol, meat and pesticides. The last set of toxins that I’ve seen addressed by popular detox diets is the heavy metals, like mercury, lead and arsenic. These can accumulate in the body through many types of exposure: by breathing polluted air, smoking, eating fish with high levels of mercury (originating from the aforementioned polluted air), from dental fillings containing mercury… sadly, there is no shortage of ways to be exposed in our modern world. Luckily for us, our body has natural mechanisms to remove these heavy metals. Once again, your liver plays a starring role, and it relies on an antioxidant that it produces itself called glutathione. Several foods in your diet support glutathione function, especially cruciferous vegetables (anything in the cabbage family– broccoli, brussels sprouts, cauliflower, bok choy, kale…) and foods that contain the mineral selenium. You can find selenium in foods such as brazil nuts (go easy…1 per day is all you need, and too much of a good thing is actually a bad thing in this case); walnuts; fish and seafood (especially scallops, shrimp, cod, tuna, salmon and snapper); mushrooms; and eggs. Get your selenium by including the foods listed above in your regular diet, rather than by taking supplements. Too much selenium can actually be toxic, and isolated selenium supplements are not recommended for generally healthy people.
OK. So that was a complex answer to a seemingly simple question. To answer my friend’s original question: the alcohol and meat you gorged on during Christmas are long gone from your body. But if you want to eat defensively to keep your natural detox systems in prime condition for St. Patrick’s Day, I’d suggest you lay off the booze, drink plenty of water and focus on a balanced diet comprised of unprocessed/minimally-processed foods to the greatest extent possible–including lots of fruits and vegetables, whole grains, small portions of nuts, and small portions of high-quality meat/fish if you’re an omnivore. (For a list of lower-mercury fish options, check out the Environmental Defense Fund’s Seafood Selector.) There’s no need to juice fast, give up meat entirely or get a colonic to clean up your inner act.
Unless of course you enjoy colonics. In which case, be my guest.Did you like this? If so, please bookmark it, RSS feed.