Whey vs Soy Protein

Whey versus Soy is an on going debate.

How is Protein Quality Determined

To compare protein quality, researchers generally use the protein efficiency ratio (PER) or the protein digestibility corrected amino acid score (PDCAAS). PER measures the weight gain in rats fed a particular protein compared the gold standard egg white protein. The higher the PER value, the greater the protein quality.

The PDCAAS method evaluates protein quality for humans by comparing the amino acid profile of a protein with the essential amino acid requirements for humans according to The Food and Agriculture Organization. A score of 1.0 means the protein meets the requirements.

Although the PDCAAS method is the internationally recognized standard for comparing proteins, it does not differentiate among proteins with a PDCAAS of 1.0 even though the PER values differ. The standard does not account for various processing methods that preserve amino acids, peptides and micronutrients that have health benefits.

There is a wealth of research on protein and the health benefits of different amino acids. Each protein source has advantages and disadvantages. Some of the benefits may depend upon how the protein was process. For example, non-pasteurized whey preserves natural protein structures that may have potential benefits not available from pasteurized whey protein.

Whey vs Soy

Soy protein and whey protein both reduce calorie intake, decrease food cravings and raise energy levels. Both proteins are gluten and cholesterol free and safe for those who are lactose intolerant. Soy and whey protein are beneficial in weight loss when added to a balanced, low-calorie diet.

Whey and soy are different in that whey comes from milk and soy comes from a plant. According to the Whey Protein Institute, whey is a more nutritionally complete protein because it contains bioactive ingredients that foster the immune system. Whey also consists of branched chain amino acids.

Soy protein does not absorb as quickly as whey protein, causing it to be slower at repairing muscle tissue after a workout.

Whey vs Soy for Weight Loss

In recent studies Whey beats Soy for weight loss.

According to research from the Nestle Research Center in Switzerland, whey protein consumed at breakfast, lunch and dinner proved more successful than either casein or soy proteins in boosting fat burning and reducing muscle loss.

They found that the total fat oxidation and energy expenditure over 5.5 hours was greater after consuming the whey protein meal versus the other proteins and all were significantly higher than the high-carbohydrate meal. (The American Journal of Clinical Nutrition, March 2011)

In another study, researchers from the US Department of Agriculture randomly assigned 90 participants to consume soy protein, whey protein or carbohydrate supplements at mealtime for 23 weeks without changing calorie consumption.

At the end of the trial, the whey group had lost body weight, fat and had a smaller waist measurement. The soy and carbohydrate groups did not show similar weight loss results. (The Journal of Nutrition, July 2011)

A study from McMaster University (June 2012) in Canada found that when compared to whey protein, ingesting soy protein after a workout or at rest does about as much as plain water for muscle protein synthesis. Soy Protein About as Good as Plain Water for Muscle Building