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in your body. There’s a hell of a lot of it in there already.
    Thinking through: if salmon DNA were absorbed whole by your skin, then you would be absorbing alien, or rather fish, design blueprints into your cells—that is, the instructions for making fish cells, which might not be helpful for you as a human. It would also be a surprise if the DNA were digested into its constituent elements in your skin (your gut, though, is specifically adapted for digesting large molecules, using digestive enzymes that break them up into their constituent parts before absorption).
    The simple theme running through all these products is that you can hoodwink your body, when in reality there are finely tuned “homeostatic” mechanisms, huge, elaborate systems with feedback and measuring devices, constantly calibrating and recalibrating the amounts of various different chemical constituents being sent to different parts of your body. If anything, interfering with that system is likely to have the opposite of the simplistic effects claimed.
    As the perfect example, there are huge numbers of creams (and other beauty treatments) claiming to deliver oxygen directly to your skin. Many of the creams contain peroxide, which, if you really want to persuade yourself of its efficacy, has a chemical formula of H 2 O 2 and could fancifully be conceived of as water “with some extra oxygen,” although chemical formulas don’t really work that way; after all, a pile of rust is an iron bridge “with some extra oxygen,” and you wouldn’t imagine it would oxygenate your skin.
    Even if we give them the benefit of the doubt and pretend that these treatments really will deliver oxygen to the surface of the skin, and that this will penetrate meaningfully into the cells, what good would that do? Your body is constantly monitoring the amount of blood and nutrients it’s supplying to tissues and the quantity of tiny capillary arteries feeding a given area, and more vessels will grow toward areas with low oxygen, because that is a good index of whether more blood supply is needed. Even if the claim about oxygen in cream’s penetrating your tissues were true, your body would simply downregulate the supply of blood to that part of skin, scoring a homeostatic own goal. In reality, hydrogen peroxide is simply a corrosive chemical that gives you a light chemical burn at low strengths. This might explain that fresh, glowing feeling.
    These details generalize to most of the claims made on packaging. Look closely at the label or advertisement, and you will routinely find that you are being played in an elaborate semantic game, with the complicity of the regulators. It’s rare to find an explicit claim: that rubbing this particular magic ingredient on your face will make you look better. The claim is made for the cream as a whole , and it is true for the cream as a whole, because as you now know, all moisturizing creams—even the cheap kinds—will moisturize.
    Once you know this, shopping becomes marginally more interesting. The link between the magic ingredient and efficacy is made only in the customer’s mind, and reading through the manufacturer’s claims, you can see that they have been carefully reviewed by a small army of consultants to ensure that the label is highly suggestive, but also—to the eye of an informed pedant—semantically and legally watertight. (If you want to make a living in this field, I would recommend the well-trodden career path—a spell in trading standards, advertising standards, or any other regulatory body—before going on to work as a consultant to industry.)
    So what’s wrong with this kind of spin? We should be clear on one thing: I’m not on a consumer crusade. Just like the lottery, the cosmetics industry is playing on people’s dreams, and people are free to waste their money. I can very happily view fancy cosmetics—and other forms of quackery—as a special, self-administered, voluntary tax on people who don’t