The Spice Wars on Meaty Microbes

In a discussion of the spleen (a seriously underappreciated organ) I omitted to mention--how could I?--that my very own brother once suffered from a spleen disease called ITP, which stands for (hold your breath) idiopathic thrombocytopenic purpura.

One of the symptoms of ITP is bruising: I still remember my mother’s consternation one day when she found fresh bruises on his body, long after he was supposedly well again. Turns out he’d been having great fun holding the vacuum cleaner nozzle to his skin and covering himself with suction marks. (Kids--they’re a riot.)

Moving on from the spleen (it’s a fabulous organ, but enough is enough) we wonder if you’ve ever noticed that, in the cuisines of the world, vegetable dishes are generally less spicy than meat dishes.

I can’t say I have, myself. But scientific inquiry has been brought to bear on the issue and recently published in an article titled “Why Vegetable Recipes Are Not Very Spicy.” (Interested readers can check it out in the June issue of the journal Evolution and Human Behavior, which publishes on anything from why people love their pets to where people put tattoos on their bodies.)

In the unspicy-vegetables study, evolutionary biologist Paul Sherman at Cornell University and undergraduate Geoffrey Hash rifled the bookshelves of the university’s School of Hotel Administration and examined 2,129 vegetable recipes in 107 cookbooks from 36 countries. Sherman and Hash compared them with 4,570 meat recipes collected from 93 cookbooks in an earlier scholarly study. And, they found, the hotter countries tended to use more spices than cooler countries--but meat dishes in all 36 countries contained more spices than the vegetable dishes.

Well, I never! Sherman believes that humankind probably started loading dishes with spices to help kill microbes that cause food poisoning--and these grow faster in hotter climes. We need those killing properties more in meat dishes than plant dishes, he reasons--because an animal fights off germs using an immune system that’s as dead as a doornail as soon as the creature dies.

Plants, however, have evolved all kinds of microbe-killing chemicals--and these keep working after the cabbage and carrots are diced and sliced. Plants also have walls that act as barriers. They have acidy juices that are harder for bacteria to grow in. They don’t need the extra ammo.

Sherman doesn’t buy other “why we eat spices” theories: that we eat them to help make us sweat and cool down (many spices don’t make us sweat, he says--and we’re pretty good at sweating on our own) or that we eat them for their antioxidants and other good chemicals. Spices, at least in food, are added in tiny quantities. If we were taking bay leaves for medical reasons, he says, surely we’d take a whole wad of them, not a mere crumbling.

Here, by the way, are the top 10 bacteria-busting spices from Sherman and co-workers’ list: garlic, onion, allspice, oregano, thyme, cinnamon, tarragon, cumin, cloves and lemon grass. The spiciest cuisine comes from Thailand, the Philippines and Malaysia. Least spicy dishes are from Sweden, Finland and Norway (where maybe more than cold keeps bugs at bay: I challenge any microbe out there to try subsisting on lutefisk).

Try This at Home ...

How on Earth do scientists figure out whether that radish, loganberry or potato peeling they’re studying contains antibacterial chemicals? I have vague memories of college labs in which we swabbed plates with sundry substances and checked whether little round colonies of bacteria would sprout up or not. (We, at least I, invariably mixed things up and discovered that bacteria simply adored Pine-Sol or that warmed beef broth killed microbes by the truckload.)

Here’s how you do it. Take a flat petri dish filled with a gelatinlike substance. Spread some bacteria evenly over the surface. Then add your rutabaga extract or whatever to a round piece of blotting paper, place it in the middle of the dish, and incubate.

If there’s a zone around the paper in which no bacterial slime grows, you’re in luck! Something in the rutabaga could be inhibiting growth. It’s time to publish! publish! publish!--and then get a business plan together for that rutabaga power juice, rutabaga health bar, and rutabaga (“nature’s miracle”) cookbook.

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If you have an idea for a Booster Shots topic, write or e-mail Rosie Mestel at the Los Angeles Times, 202 W. 1st. St., Los Angeles, CA 90012, rosie.mestel@latimes.com.