These days, there's a protein powder for everyone. Hemp, soy, rice; muscle building, dieting, meal replacement—you name it. While it used to be simple—weight lifters head to aisle three for protein—the proliferation of choices has also brought more confusion. However, wending your way through the ins and outs of protein powders can be simplified with some basic knowledge.

Proteins are compounds made up of amino acids. There are 20 amino acids, 12 of which the body can synthesize. The other eight need to come from food and are therefore known as essential amino acids. There is some controversy over how many essential amino acids there actually are. Histidine is known to be essential in children, and is often included in the essential list. Arginine is considered conditionally essential for small populations and might also make the list. Therefore, you might encounter a list of "essential" amino acids ranging from eight to 10.

The (confusing) math of protein nutritional value

The U.S. Food and Drug Administration, as well as the Food and Agriculture and World Heath Organizations of the United Nations, use the Protein Digestibility Corrected Amino Acid Score to determine a protein's nutritional value. The PDCAAS is calculated by dividing the percentage of a particular amino acid in a test protein by the percentage in an ideal formulation of that protein and then multiplying by the digestibility. There is some debate about what "digestibility" really means. Also, the protein reference pattern values were calculated using the essential amino acid requirements of a preschool child.

Here are some PDCAAS values according to the UCLA Center for Human Nutrition. The highest score is 1.0:

Casein (a milk protein): 1.0
Whey: 1.0
Soybean isolate: 1.0
Beef: 0.92
Garbanzo beans: 0.66
Lentils: 0.52
Hemp: 0.46
Whole wheat: 0.40

Other methods of calculating a protein's nutritional value include the Biological Value and Net Protein Utilization scales. Protein scales tend to have a fair amount of variability, as numerous factors play into digestibility and utilization.

Proteins are an integral part of cell processes, from metabolism to immune response to muscle building, but not all proteins are created equal. Each has its benefits and possible drawbacks, depending on a person's needs.

Whey protein

That "water" that sits on top of your yogurt or cottage cheese is actually whey. It's turned into powder concentrate form by removing the lactose via filtration. More filtering yields a whey protein isolate, which has fewer impurities such as lactose. That isolate is then spray-dried and combined with lecithin to improve dissolvability and to produce the final powder.

According to Jay Robb, clinical nutritionist and chief operating officer of Jay Robb Enterprises, a nutritional supplements manufacturer based in Carlsbad, Calif., "The most highly filtered, highest-quality and most expensive of [whey protein isolates] range in protein content from 90 percent to 98 percent."

Lisa Dorfman, R.D., a sports nutritionist and adjunct professor at the University of Miami, says higher-grade protein isolate is more easily absorbed—and more expensive. Finding companies that use this higher-grade isolate is key to finding a quality powder, Robb says.

As for whey's benefits, Dorfman says, "Whey has been shown to be a better recovery protein, assisting with muscle repair and preventing muscle breakdown." Robb agrees and adds, "Besides increasing muscle tone, whey protein has numerous health benefits," including boosting immune and cardiovascular health and building bone density.

For regular folks not looking to build muscle, Robb says, "Like other proteins, [whey] also makes you feel full more quickly and for a longer period of time, so you don't feel the urge to overeat or snack between meals."

Certified organic whey protein powder is available, but Robb says the quantities are still too small— but growing. His company plans an organic line for early next year.

Soy protein

According to Dorfman, soy is the most complete vegetable protein available and, like whey protein, comes in soy concentrate and isolate. James Gibbons, president of Nature's Plus, a Melville, N.Y.-based energy supplements manufacturer, says there is the possibility of some confusion as both terms are in current use. Soy protein isolate can represent the entire spectrum of proteins isolated from soy, he says. Manufacturers may then add back in soy isoflavones, the antioxidant portion of soy.

As with whey, there are levels fo purity among soy isoflavones. Gibbons says, "Lower-quality proteins often taste bitter, are difficult to digest and are nutritionally inferior." It therefore pays to discuss the protein quality of the brands that you sell with manufacturers.

Gibbons says soy's usefulness for athletes and weekend warriors should not be written off as inferior to whey, often considered the king of proteins for athletes. "Contrary to popular belief, soy protein has been tested and found to be an excellent adjuvant for endurance and muscle-building exercise regimens," he says. "Its high digestibility makes it an outstanding source of amino acids for post-workout recovery and muscle growth."

And, as Dorfman says, soy has added heart-health cachet. Customers might very well come in asking for soy just for this reason.

Hemp protein

Hemp continues to be a new ingredient darling, with hemp-based products proliferating like weeds. Protein powder is no exception. "Concentrated natural hemp has a high fiber content, omega-3 and -6 essential fatty acids, vitamins, minerals and antioxidants—all necessary ingredients for good health," Dorfman says. Hemp also contains all the essential amino acids, though Dorfman says five are at levels below the minimum reference pattern.

Mike Fata, president and co-founder of Manitoba Harvest Hemp Foods & Oils, based in Winnipeg, Manitoba, Canada, says hemp is easy to digest and assimilate and is not known to be an allergen, a bonus for allergy sufferers looking to up protein intake. "Hemp also contains a high level of the branched-chain amino acids that play a key role in the repair and growth of lean body mass—of particular importance to athletes." In addition, Manitoba Harvest's cold-press and cold-milling processes ensure that enzymes, vitamins, minerals and nutrients are not destroyed, Fata says.

One trade-off of sorts with hemp powder as opposed to hemp oil is that while the powder contains fiber, its omega-oil content is much smaller. Retailers should be aware of the difference when recommending EFA products to their customers.

Fata adds that hemp protein powder has a non-nutritional benefit—it's eco-friendly. "Hemp is naturally pest-resistant, and because hemp plants grow rapidly and close together, they crowd out weeds and don't need herbicides. Hemp's only fertilizer requirement is nitrogen, which can be provided by manure."

Eggs and rice are also nice

Two other popular protein-powder ingredients are egg and rice proteins. According to LisaDorfman, R.D., a sports nutritionist and adjunct professor at the University of Miami, egg protein is high in branched-chain amino acids and is completely and easily absorbed by the body.

Jay Robb, clinical nutritionist and chief operating officer of Jay Robb Enterprises, agrees and adds, "Egg protein comes from the white of the egg, so it is high in protein and fat-free." He says it also has no cholesterol and is high in the amino acid arginine, which causes "your blood vessels to relax, which means lower blood pressure for you and an increase in your blood flow."

Rice protein is isolated from brown rice and contains all essential and nonessential amino acids, Dorfman says. Rice protein is also hypoallergenic and has been shown to reduce cholesterol levels in clinical studies.

Mix and match proteins

Because of the variability in digestibility scores among various types of proteins and the vagaries of each individual's digestive system, combining proteins might give customers the extra insurance that all the amino acids are being absorbed in adequate amounts, Dorfman says. "Most powder supplements contain their own proprietary blend of different proteins." Nature's Plus, for example, uses a patented blend of soy, fermented soy, rice and pea proteins.

As with all the products you stock, quality is the main ingredient. "Cheap proteins may be deficient in some essential amino acid," Gibbons says. "They may taste bitter. And they may leave customers unhappy and averse to [protein powder] forever."

If your customers are worried about digestive issues, they can always go the old-fashioned way—experiment with different types. With all the choices available, they're sure to find one that works for them.

Bryce Edmonds is a freelance writer—and protein powder aficionado—in Boulder, Colo.

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