Humans, perhaps Westerners in particular, tend to share a certain creed that goes something like this: If one is good, two are better.
That's fine when it comes to dollars in the collection plate or hours spent volunteering, but not so with certain items consumed in the name of health. Think nuts, red wine, dark chocolate, coffee.
Nuts, for instance, once thought to be merely delicious and fattening, are - well, delicious and fattening. They've also been shown to be full of all sorts of good things such as omega-3 fatty acids. Thus dietitians recommend an ounce (28 grams) of them (especially walnuts and almonds) several times a week for health benefits.
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Doesn't it stand to reason that if one ounce is recommended a few times a week, two ounces (56 grams) every day would be better?
In a word, and a very firm one at that: no, says Linda Michalsky, assistant professor of clinical nutrition at the University of Texas Southwestern Medical Centre.
"A handful of nuts is good, but just a handful. Palm-size. A small woman's palm's size, not the whole bag."
Too many nuts equal too much fat and too many calories. Unless, of course, you're compensating by cutting back on something else, which is not very likely.
"I'm a chocoholic," says Michalsky, a registered dietitian who holds a doctorate in nutritional sciences. "I make the choice between putting butter on a sandwich or having chocolate later on. But too much dark chocolate won't be good for anybody. It's moderation. I've been preaching moderation for decades. It all comes down to a general balanced diet."
Her moderation soapbox is shared by fellow experts, including Amanda Smith of the University of Texas at Dallas.
"Overconsumption of anything can lead to negative effects," says Smith, assistant director of the school's Student Wellness Center. "What has us concerned are studies coming out about things like red wine. They tell you a glass a night is healthy. But we Americans are so into, 'if one is good, 14 are better'."
Justification, she says, is as close as the internet.
"If you want to hear that drinking that amount is good, you can find it. In this country, it's our mentality. We want quick fixes, we want miracle cures, and we want them right now."
Thus, someone who hears that drinking a glass of red wine will give health benefits could easily think, "I want two weeks' worth today so I can see the results quicker."
Someone who reads that coffee can help prevent Alzheimer's disease might up their intake of drinks that include coffee, which usually come with a high-calorie price tag.
A health-conscious person could take "dark chocolate has healthy flavonoids" to mean a lolly-bar buffet.
Good health isn't something you reach and then are set for life. It's an ongoing quest.
Regarding the studies, Michalsky offers this caveat: "Most of the pure studies are saying that doing this or that may have a beneficial effect," she says. "They're not saying you should go out and do it. Coffee isn't bad for you in certain amounts, or alcohol if you're already drinking it."
Remember these when deciding what to eat or not to eat:
No one thing can make you healthy.
"Variety gives you a wider variation of nutrients, some we haven't even discovered yet," Michalsky says.
Portion sizes count.
"You could get fat on oatmeal, peanut butter and grilled chicken," says Amy Goodson of Texas Health Fort Worth Hospital. "Excess calories, whether you eat chocolate or whole-wheat pasta, can add weight."
Think it through.
"Caffeine is addictive. Consuming too much increases your heart rate," Smith says. "Yes, wine has cancer-fighting agents. But if you drink too much, you need to worry about alcohol dependency. People just think of the good parts, not 'how can this affect me negatively?'"
Take small steps.
"At least have something healthy in your diet," Michalsky says. "What's the best thing to do? Everything in moderation."