The potato chip celebrated its 150th birthday last year.

This staple of the $22 billion salty snack industry -- believed to have been created by a cook in Saratoga Springs, N.Y., after a customer complained that his fried potatoes weren't crunchy enough -- just keeps on selling as Americans ride a roller-coaster of diet trends.

THE AISLE FILES This is the first in a series of articles reviewing the health benefits -- or lack of benefits -- found in grocery store aisles by Health Editor Virginia Linn, with Madelyn Fernstrom, director of Center for Weight Management at University of Pittsburgh Medical Center. Here are the remaining articles: Part Two: Dairy overload Part Three: Cereal solutions Part Four: Meaty matters Part Five: We love our daily bread Part Six: Here's how to pack your child a healthy school lunch Part Seven: Not your grandma's TV dinners

Just last week, industry folks attending an expo in Philadelphia for the 800 companies represented by the Snack Foods Association were contemplating new cooking formulas to adapt their products to the ongoing low-carb craze. Some brands have made adjustments, but most are relying on Americans' continued preference for the comforting taste of salty or high-fat snacks that has sustained the industry.

Indeed, take a look in the modern grocery store and you'll see aisles and aisles and dozens of free-standing displays filled with snack foods: chips, pretzels, popcorn and nuts; Entemann's cakes and cookies; Krispy Kreme doughnut displays; breakfast and granola bars, Fruit Roll-ups, Goldfish cheese crackers; chocolate bars, licorice, lollipops and seasonal Easter candy and cakes.

"It's the result of the grab-and-go-generation,'' said Judy Dodd, a registered dietitian and food and nutrition advisor for Giant Eagle, the region's largest grocery store chain. "People are not sitting down for three square meals anymore.

"Snack foods are now considered meals. It fits the needs, that's why it's everywhere: People are looking for the quick and easy: the grabable, packable, fits-into-the-soccer-bag snack that doesn't require refrigeration.''

"The consumers are demanding that their choices be met.''

So, with all these choices, which are the healthiest?

The Post-Gazette recently accompanied obesity expert Madelyn Fernstrom on a trip to a store snack aisle to analyze what's best and what's worst among the chips, candies and cookies. It's the first of six visits in which she'll give advice on choices from the dairy case to the frozen foods section.

Wise selections are particularly important in the wake of the recent federal study predicting that more Americans will die of obesity than from smoking. To combat this epidemic, even the World Health Organization has floated the idea of pushing for a "Twinkie tax'' on fast foods and snacks of low nutritional value.

	Some of the choices you might make in the snack aisle: The best vs. the worst

True, you should probably be nibbling on an apple between meals. But Fernstrom, the director of the Center for Weight Management at University of Pittsburgh Medical Center, recognizes that shoppers need realistic options, too. Some snacks are better than others, but the most important strategy is to limit your portion sizes, she says.

With chips, choose packages that limit portions for you. Single-serve packages of chips are more expensive than the multiple-serving, 10- to 12-ounce bags and may look puny, but it's enough, she says. ''This gives you the satisfaction of eating to the bottom of the bag.''

Chips, on average, are 10 calories a piece, but there is a range. Doritos in all flavors have the fewest calories -- 140, 70 of them from fat -- in a 1-ounce bag. The small bag of Fritos has 200 calories, Cheetos 180. But even that difference is not that great, she says.

"The main issue is portion size, not the selection,'' she says.

Watch out for labels such as "natural,'' which means the product has no preservatives or artificial flavors or coloring. It doesn't mean fewer calories. A baked chip cuts the calories and fat (for regular Ruffles, 12 chips have 160 calories and 10 grams of fat vs. 10 chips at 120 calories, 3 grams of fat for the baked version). But baked chips may not taste as good or make people feel full enough to curb nibbling.

Our shopping guide Madelyn Fernstrom has a "tremendous sweet tooth" herself. Her favorite candy is the snack-size bag of M&Ms at 110 calories. Other snack favorites: minibag of Smartfood Cheddar Cheese popcorn and minbag of Honey Maid Stix. Click photo for larger image.

"It's still about 10 calories a chip. You might be better off with single portions of regular Ruffles.''

Regular pretzels are lower in fat and calories, but even those add up if you eat too many. Frito-Lay Wow! brand, made with the nondigestable fat Olestra, is lowest in calories and fat, but may cause gastrointestinal problems if you eat more than one serving.

Stay away from the 3.5-ounce bags of Cracker Jack, Crunch 'n Munch or other such foods. To the eye, the bags are just slightly larger than the single-serve packages, but actually contain 3 1/2 servings. So if you nibble to the bottom of the bag, you're eating 420 calories, instead of just 120.

Marketers often display snacks with the popular condiments and dips that go with them. You'll find chips next to high-fat cheese spreads or french onion dip. Your best choice is the salsa.

Regular popcorn is a good choice, she says, but like chips, choose the snack-size packets that yield about 110 calories per bag. Stay away from the pour-overs, such as Orville Redenbacher's Cinnabon, that add oodles of a calories and fat to an ordinarily healthful selection.

Peanut butter cheese crackers at 200 calories a package, are "an acceptable snack," Fernstrom says. Cheez-Its, at 180 calories a serving for an active child, is no better or worse than chips.

In the cookie aisle, Fernstrom dove for the single serving packs of Honey Maid Cinnamon Stix at 120 calories, 2.5 grams of fat. "This is a really good choice. This can really save calories.''

Any of the single-serving packs of mini cookies -- Oreos, Chips Ahoy!, etc. -- also are OK, although they'll have 60 to 80 calories more than the grahams. She's not a fan of fat-free cookies such as SnackWell's, which may cut the fat, but still carry the same amount of calories as regular cookies. People often over-indulge on these thinking they're a good choice.

And whatever you do, stay away from any cookie that is double-stuffed.

"Avoid double anything,'' she says.

For candy, two mini candy bars can help stave off your hunger and have far fewer calories than a full-size bar. Here's the difference: a full-size 3 Musketeers is 260 calories; two mini-bars are 70 a piece, for a total of 140.

If you're looking to reduce the fat, but not calories, go for licorice, Mike-N-Ikes, Good & Plenty. Sucking candies such as Creme Savers (25 calories a piece) also can take the edge off your hunger. Lollipops -- Dum-Dums pops, 12 calories; Tootsie Roll Pops, 60 calories -- take a while to eat. Sugarless gum, especially in cinnamon flavor, keeps the mouth busy.

Considered "toxic" because of their packaging are the 10- to 12.5-ounce bags of Reese's Bites, mini Kit-Kats, Pop'ables and other pouches of small chocolate candies. Again, the smallish bag invites repeated hand-dipping and calorie overload. Relatively new in the check-out lanes are the 99-cent, 2.75-ounce, one-serving-size versions of these bags. Buy at your peril -- they each hold 400 calories or more.

Since the snack industry bases its marketing strategy on impulse buying, don't go to the store hungry. And take a list. That will help deter you from reaching for those big boxes of Entemann's cookies that have been strategically placed just within arm's reach in a special display.

Next month: The dairy case.