Journal Title (Medline/Pubmed accepted abbreviation): Appl. Physiol. Nutr. Metab.
Page Numbers: 484-489
Background: Protein bars are extremely popular and are often marketed as "health foods". In addition to protein, these bars often include lots of sugar (or sugar alcohols) as well as total fat, saturated fat, and cholesterol. Sugar alcohols are sweet like sugar but contain fewer calories and, on their own, do not lead to a spike in blood sugar after consumption. Although these bars are marketed as “healthy”, it is unknown if they do in fact elicit a healthier physiological response than a regular candy bar.
Hypothesis: Consumption of the protein bar will lead to similar responses in blood glucose, insulin, cholesterol, and triglyceride (fat) levels in the one hour after consumption.
Experimental Design: randomized cross-over design
Subjects: Healthy, active males (n = 5) and females (n = 5), age 24 ± 5.5 y
Protein bar: Supreme Protein® Carb-Conscious Caramel [96 g, 360 kcal, 16 g fat, 20 mg cholesterol, 34 g carbohydrates, 4 g sugar, 27 g sugar alcohol (maltitol), 30 g protein]
Candy bar: Snickers® bar (75 g, 355 kcal, 18 g fat, 10 mg cholesterol, 45 g carbohydrates, 40 g sugar, 0 g sugar alcohol, 5 g protein)
Protocol: The participants consumed one of each of the treatments one week apart. On the day of the testing session, they arrived at the laboratory after an overnight fast. Height, weight, blood pressure, and heart rate were measured. After a baseline blood draw, the participant consumed one of the bars. Blood was drawn 15, 30, 45, and 60 min after consumption. Blood was analyzed for glucose, insulin, cholesterol, and triglyceride concentration.
- The candy bar led to maximum blood glucose concentrations of 6.2 ± 0.8 mM 15 min after consumption (multiply blood glucose level in mM by 18.02 to get mg/dL). The protein bar also led to peak blood glucose concentrations after 15 min but blood glucose peaked at 4.9 ± 0.5 mM (p < 0.05), which was very similar to the baseline blood glucose level.
- Both bars led to a fall in blood sugar below baseline at 45 min and even further at 60 min. Specifically, 60 min after consumption of the bar, blood glucose was 2.3 mM for the protein bar session and 3.0 mM for the candy bar session.
- Blood cholesterol was slightly greater at every time point after consuming the protein bar vs. the candy bar but differences were not statistically significant.
- Serum insulin concentrations peaked 15 min after consumption of the candy bar at 48 ± 32 μIU/mL. In contrast, serum insulin concentrations peaked 30 min after consumption of the protein bar at only 32 ± 14 μIU/mL. There was a lot of variation in insulin concentration between individuals and, therefore, differences between treatments were not statistically significant.
- Serum triglycerides tended to increase with time for both groups over the hour. The protein bar led to slightly greater concentrations at each time point, though the differences were not significantly different.
Key practice applications: As it was designed, the carb-control protein bar did not spike blood glucose concentrations after consumption. However, both bars led to a robust insulin response which likely was responsible for the extremely low blood glucose concentration observed 45 min after consumption. Blood glucose concentrations below 3.9 mM can lead to a reduced coordination and focus. In conclusion, a candy bar-like protein bar elicited similar insulin, cholesterol, and fat profiles for the one hour following ingestion; replacement of the sugar with sugar alcohols prevented the immediate rise in blood sugar after ingestion.