Self & Other · The Things That Sound Like They Help (But Mostly Don’t)
Zinc, Briefly
Most other herbal “immune support” products have weaker evidence than echinacea or elderberry. Many have essentially nothing beyond traditional use, which is a real category of human knowledge but not a substitute for clinical trials. A remedy used for a thousand years has, by definition, not killed everyone who used it; that is not the same as proof that it works.
A practical point. The supplement industry, in the United States and many other countries, is regulated more loosely than the pharmaceutical industry. Manufacturers do not have to prove that their products work before selling them. They can use vague language (“supports immune function,” “promotes wellness”) that the FDA does not police closely. The contents of the bottle are not always what is on the label, and independent testing has repeatedly found supplements that contain too little of the listed ingredient, too much of it, or sometimes none at all. Caveat emptor applies particularly hard.
Zinc, Briefly
Zinc is one of the few supplements with somewhat better evidence in cold and flu treatment, and it is worth a brief discussion.
Some studies, particularly of zinc lozenges taken at the very onset of a cold, have shown a real but modest reduction in duration. The effect is more reliable with high-dose zinc acetate or zinc gluconate lozenges than with zinc nasal sprays (which have been associated with rare cases of permanent loss of smell and should generally be avoided) or zinc supplements taken as pills. The mechanism appears to involve direct inhibition of viral replication in the throat, where the lozenge dissolves.
Zinc lozenges may shorten a cold by a day or so if taken consistently from the moment symptoms begin. They are not a treatment for the flu or for serious infections. They have side effects — mostly nausea and a metallic taste — that some people find worse than the cold. Long-term high-dose zinc supplementation can cause copper deficiency. Of the over-the-counter remedies for the common cold, this is the one with the cleanest evidence for any benefit.
Cleanses and Detoxes
The cleanse-and-detox industry sells products and protocols designed to remove “toxins” from the body, with claims that doing so will improve immune function, energy, mental clarity, and other things.
The most fundamental problem is that the human body has, built-in, an extremely sophisticated detoxification system. The liver processes essentially every chemical that enters your bloodstream, neutralizing or tagging things for excretion and sending them out through bile or urine. The kidneys filter your blood roughly thirty times a day. The lungs clear volatile compounds with every exhalation. The skin sheds and replaces itself constantly. None of these is going to be improved by a juice cleanse, a colon cleanse, or a foot bath that turns brown.
The “toxins” being marketed are usually unspecified. When pressed, manufacturers either name vague categories (heavy metals, pesticides, environmental pollutants) or refuse to specify. There is no validated test that shows whether a cleanse has removed any of them, because there is no specific thing being removed. The brown color in the foot bath is iron oxide produced by the electrodes reacting with salt water, regardless of who has their feet in it. This has been demonstrated repeatedly.
Juice cleanses deserve a closer look because they feel intuitively healthy. Drinking only juice for several days will change your body. You will lose weight, mostly water and some glycogen. You will have low blood sugar, and depending on your particular biology you may feel either wonderful or terrible. The juice contains vitamins, which are good. It also contains an enormous amount of fructose without the fiber that normally comes with whole fruit, which is hard on your liver. There is no “toxin” being flushed out; the things juice flushes (water, electrolytes, some calories) are things your body was already managing.
The colon-cleanse industry is somewhat worse. The colon does not need cleaning. It is, by design, full of bacteria doing useful work, as we discussed in Chapter 5. Aggressive cleansing can disrupt the microbiome, cause electrolyte imbalances, and in some cases damage the colon wall. There is no medical condition for which colon cleansing has been shown to be beneficial outside of preparation for a colonoscopy.
If you have done a cleanse and felt better afterward, that is real and worth understanding. The most likely reasons: you ate fewer ultra-processed foods; you drank more water; you slept better because you cut out alcohol or caffeine; you spent some time taking deliberate care of yourself, which is its own form of medicine. None of these requires the cleanse part. You can keep the underlying changes without the rest.
Probiotics
Probiotics are an interesting case because the underlying biology is real and the marketing has run far ahead of the evidence.
The biology, from Chapter 5, is that the gut microbiome is a real and important system. The bacteria living in your colon do measurable work for you, and disrupting that community — with antibiotics, with poor diet, with serious illness — can have real consequences. The idea that you might restore or improve a damaged microbiome by eating particular bacteria is biologically reasonable.
The execution in commercial products is mostly weaker than the marketing suggests.
First, most of the bacterial strains in commercial probiotics do not establish long-term residence in the human gut. They pass through. Whatever effects they have, they have transiently. They do not “rebuild” your microbiome; they visit it.