Do Protein Bars Give You Gas?

woman eating a protein bar

The Bottom Line

Protein bars often contain compounds called sugar alcohols, which are lower in calories than traditional sugars. Sugar alcohols are associated with multiple gastrointestinal side effects including abdominal pain, bloating, and gas.

man with a stomach ache

The Full Story

The word “protein” is derived from the Greek word “proteios”, or primary, and proteins are an important primary source of nutrition. Proteins contain amino acids, many of which cannot be made by the human body and must be obtained through dietary sources. When consumed, the body breaks down proteins into their amino acid components, and these amino acids are then used to sustain healthy cell growth and function. It’s important to maintain a normal protein balance, as too little or too much protein can cause serious disease.

There are many sources of protein in our diets, including meat, dairy, fish, and animal products. However, vegetable-based proteins account for the majority of dietary protein intake worldwide. In the Western diet, wheat (especially in the form of bread) represents the largest source of protein. In other parts of the world, corn is a main protein staple. Other cereal proteins, including rice, represent additional sources of protein. While pure milled rice and rice flour are not good sources of protein, rice can be processed into byproducts that contain large amounts of protein. There are also more than 200 species of insects that are used as food, providing alternative sources of protein for many individuals worldwide. 

More and more people have realized that protein intake is a significant factor in maintaining a healthy lifestyle, and because of this there has been an increased worldwide demand for protein-rich foods. Plant-based protein has surged in popularity in recent years, and many individuals also consume protein bars on a regular basis.

Protein bars are typically made from protein powder, sugar syrup, and fat. Because of an increased consumer demand for healthier, low-calorie products, many protein bar formulations include sugar alcohols instead of traditional sugar sources such as fructose, glucose, or sucrose. Sugar alcohols, including xylitol, sorbitol, mannitol, and erythritol, are naturally present in small amounts in fruits and vegetables and have varying levels of sweetness compared with traditional sugar. These compounds have a lower nutritional value and lower caloric content than traditional sugars, because they are poorly absorbed from the human gastrointestinal system after consumption and are instead broken down within the intestines by bacteria present within the gut. Because of this, sugar alcohols have only minor effects on blood sugar and insulin levels. In addition, some sugar alcohols have unique properties that distinguish them from traditional sugars. For example, xylitol prevents the growth of oral bacteria that contribute to dental plaque and cavities. For this reason, xylitol is often found as an ingredient in “sugar-free” chewing gums and candies. However, xylitol causes severe poisoning, including low blood sugar levels and liver disease, when consumed by dogs.

There are some adverse effects associated with the consumption of sugar alcohols in humans. Some scientists believe that the intestinal breakdown of sugar alcohols by gut bacteria adversely affects the intestinal microbiome and may contribute to the development of obesity. Because they are poorly digestible, sugar alcohols can also cause gastrointestinal side effects including abdominal pain, bloating, and gas. Sugar alcohols can have a laxative-like effect on the intestines and cause diarrhea. These undesirable gastrointestinal effects typically occur after consumption of high doses of sugar alcohols, but some people are more sensitive to the laxative effects and may develop symptoms after consumption of smaller quantities. The occurrence of gastrointestinal side effects also depends on other factors including individual body weight, whether the consumed product was liquid or solid, and the type of sugar alcohol consumed. Erythritol undergoes more intestinal absorption than other sugar alcohols, leading to fewer side effects when compared to other similar compounds.

For questions about unexpected or undesirable effects after exposure to sugar alcohols, including xylitol and sorbitol, contact poison control for expert advice. There are two ways to contact poison control: online at www.poison.org or by calling 1-800-222-1222. Both options are free, confidential, and available 24 hours a day.


Kelly Johnson-Arbor, MD
Medical Toxicologist

Poisoned?

Call 1-800-222-1222 or

HELP ME online

Prevention Tips

  • Read food labels carefully to understand the ingredients.
  • Eat a balanced diet, including fruits and vegetables as well as protein sources.
  • Do not allow dogs to consume products that contain xylitol.

This Really Happened

A 12-year-old girl presented for medical evaluation of chronic abdominal pain and cramping. These symptoms occurred several times a week and were accompanied by diarrhea. A physical examination and laboratory evaluation were unremarkable. Further history revealed that the girl chewed one to two pieces of sorbitol-containing “sugar-free” gum, several times a week. She also drank “light” drinks and ate diet cereal bars on a regular basis. When the “sugar-free” and diet products were eliminated from her diet, her gastrointestinal symptoms completely resolved.

For More Information

Eat Any Sugar Alcohol Lately? (Yale New Haven Health)

What You Should Know About Sugar Alcohols (Cleveland Clinic)


References

Ewy MW, Patel A, Abdelmagid MG, Mohamed Elfadil O, Bonnes SL, Salonen BR, Hurt RT, Mundi MS. Plant-Based Diet: Is It as Good as an Animal-Based Diet When It Comes to Protein? Curr Nutr Rep. 2022 Jun;11(2):337-346.

Grembecka M. Sugar alcohols- their role in the modern world of sweeteners: a review. Eur Food Res Technol. 2015;241:1-14.

Granja C. Recurrent abdominal pain caused by sorbitol malabsorption. Glob J Pediatr Neonatal Care. 2020;3:1-2.

Henchion M, Hayes M, Mullen AM, Fenelon M, Tiwari B. Future Protein Supply and Demand: Strategies and Factors Influencing a Sustainable Equilibrium. Foods. 2017 Jul 20;6(7):53. 

Hyams JS. Sorbitol intolerance: an unappreciated cause of functional gastrointestinal complaints. Gastroenterology. 1983 Jan;84(1):30-3.

Janket SJ, Benwait J, Isaac P, Ackerson LK, Meurman JH. Oral and Systemic Effects of Xylitol Consumption. Caries Res. 2019;53(5):491-501.

Mäkinen KK. Gastrointestinal Disturbances Associated with the Consumption of Sugar Alcohols with Special Consideration of Xylitol: Scientific Review and Instructions for Dentists and Other Health-Care Professionals. Int J Dent. 2016;2016:5967907. 

Malecki J, Tomasevic I, Solowiej BG. The influence of the syrup type on rheology, color differences, water activity, and nutritional and sensory aspects of high-protein bars for sportsmen. J Food Qual. 2022;2317676:1-12.

Ortolani JM, Bellis TJ, Griego MD. Xylitol toxicosis and serotonin-like syndrome occurring simultaneously in a dog secondary to ingestion of Natrol 5-HTP Fast Dissolve Tablets. Clin Case Rep. 2018 Nov 8;7(1):5-10.

Payne AN, Chassard C, Lacroix C. Gut microbial adaptation to dietary consumption of fructose, artificial sweeteners and sugar alcohols: implications for host-microbe interactions contributing to obesity. Obes Rev. 2012 Sep;13(9):799-809.

Shih FF, Daigle KW. Preparation and characterization of rice protein isolates. J Am Chem Soc. 2000;77:885-889.

Storey D, Lee A, Bornet F, Brouns F. Gastrointestinal tolerance of erythritol and xylitol ingested in a liquid. Eur J Clin Nutr. 2007 Mar;61(3):349-54.Wu G. Dietary protein intake and human health. Food Funct. 2016 Mar;7(3):1251-65.

Zumbé A, Lee A, Storey D. Polyols in confectionery: the route to sugar-free, reduced sugar and reduced calorie confectionery. Br J Nutr. 2001 Mar;85 Suppl 1:S31-45.  

Poisoned?

Call 1-800-222-1222 or

HELP ME online

Prevention Tips

  • Read food labels carefully to understand the ingredients.
  • Eat a balanced diet, including fruits and vegetables as well as protein sources.
  • Do not allow dogs to consume products that contain xylitol.

This Really Happened

A 12-year-old girl presented for medical evaluation of chronic abdominal pain and cramping. These symptoms occurred several times a week and were accompanied by diarrhea. A physical examination and laboratory evaluation were unremarkable. Further history revealed that the girl chewed one to two pieces of sorbitol-containing “sugar-free” gum, several times a week. She also drank “light” drinks and ate diet cereal bars on a regular basis. When the “sugar-free” and diet products were eliminated from her diet, her gastrointestinal symptoms completely resolved.