Editor's note: This is the first of a two-part series on health claims on food labels.

When you're walking through the supermarket, the claims on the food packaging can be dizzying and confusing.

While the food label is intended to help consumers make better choices, unfortunately, "The rules for what may appear on the label (or packaging) are influenced by food-industry petitions and responses, court decisions and the philosophy and politics of the party in power," says Luise Light, author of "What to Eat: The Ten Things You Really Need to Know to Eat Well and Be Healthy" (McGraw-Hill, 2005).

"Sometimes confusion occurs, but the original intention was really to limit manufacturers from making claims that weren't valid," says Catherine M. Champagne, a nutrition professor at Pennington Biomedical Research Center.

Here is a rundown on what you should know about the two types of health claims:

Authorized (aka Significant Scientific Agreement) Health Claims

What they mean: This is the gold standard. Authorized health claims characterize a relationship between a substance and a disease or a health-related condition (such as high blood pressure), and are supported by scientific evidence. There are now 12 such claims.

They are sometimes called unqualified health claims because they meet the significant scientific agreement standard and do not require a qualifying statement. An authorized health claim must withstand the greatest scientific scrutiny before it is approved, says Lona Sandon, a spokeswoman for the American Dietetic Association.

What makes something an authorized health claim?

The standard of scientific validity includes two components: the totality of the publicly available evidence must support the substance/disease relationship that is the subject of the claim, and there must be significant scientific agreement among qualified experts that the relationship is valid.

Why they matter: Of all the claims, these might help us the most. According to Sandon, "The public deserves health information based on fact, not fiction or opinion. Health claims are designed to protect the consumer from false or misleading marketing information about food."

How do you know it's an authorized claim?

The statement will include words such as "may reduce risk" or "might reduce risk" but does not specify a degree of risk. The statement must also imply that disease is based on several factors, not just one nutrient alone, says Sandon.

Example: "Diets low in sodium may reduce the risk of high blood pressure, a disease associated with many factors."

What's the most important, relevant health claim?

That fruits, vegetables and whole-grain products containing fiber, particularly soluble fiber, lower risk of coronary heart disease.

QUALIFIED HEALTH CLAIMS

What they mean: Qualified health claims are supported by scientific evidence, but do not meet the significant scientific agreement standard required for the FDA to approve an authoritative claim.

Why they matter: If you're trying to prevent or treat a specific disease, they help create awareness and help the consumer cut through other sources of information, says Lauren Swann, a food consultant with Concept Nutrition, in Bensalem, Pa.

How can you recognize a qualified health claim on a food label?

Look for a qualifying statement, such as "supportive but not conclusive," or "very limited and preliminary scientific research," or "scientific evidence suggests but does not prove" or "limited scientific evidence."

Example: Walnuts and coronary heart disease: "Supportive but not conclusive research shows that eating 1.5 ounces per day of walnuts as part of a low-saturated fat and low-cholesterol diet and not resulting in increased caloric intake, may reduce the risk of coronary heart disease. See nutrition information for fat (and calorie) content."

What's the most important, relevant qualified health claim?

"The one relating to omega-3 fatty acids and reduced risk of coronary heart disease," says Champagne.

Next week: structure/function claims, nutrient content claims and dietary guidelines.

Charles Stuart Platkin is a nutrition and public-health advocate, and author of "Breaking the FAT Pattern" (Plume, 2006). Sign up for the free Diet Detective newsletter at www.dietdetective.com.