Complex Carbs

What Is It?
Health Benefits
Dosage Information

Guidelines for Use

General Interaction

Possible Side Effects



Evidence Based Rating Scale

What Is It?

Complex carbohydrates, primarily starches, are long chains of sugar molecules. These large chain sugar molecules are also known as polysaccharides, which can be composed of various numbers of monosaccharides (simple sugars) and disaccharides.

The three types of complex carbohydrates of nutritional importance are fiber, starch, and glycogen. Fiber refers to foods, which the human body cannot break down. Dietary fiber can be classified as soluble or insoluble. Examples of dietary fiber include beans, oatmeal, and the skins of fruits and vegetables. Starch, primarily found in grains, cereals, breads, and pastas, is the major source of carbohydrate in the diet. It is the storage form of carbohydrates in plants, comparable to glycogen, which is the storage form of carbohydrates in humans. Glycogen, commonly known as animal starch, is a starch-like substance in the liver and muscle tissue that is changed to glucose when it is needed for muscular work and for liberating heat. Glycogen is not included as one of the complex carbohydrates in foods because there are only insignificant amounts in food.


Health Benefits

Complex carbohydrates are important for several reasons. Starch and glycogen represent energy sources for the body while fiber has strong links to disease prevention. Fiber is not a single substance, but represents a large group of different compounds with a variety of effects in the human body. However, all types of fiber are parts of plants that cannot be digested by enzymes in the human intestinal tract. High fiber foods may be beneficial because they tend to be rich in antioxidants and low in Fat and calories.

Specifically, complex carbohydrates may:

Reduce the risk of certain cancers. In a recent Chinese study, 438 women with breast cancer were compared to 438 controls without breast cancer. The study participants were interviewed about their dietary intake over fourteen months. High consumption of total dietary fiber and fiber from vegetables and fruit was associated with a decreased breast cancer risk. (1) A diet high in fiber may also benefit breast cancer survivors by reducing the inflammation that is a risk factor for breast cancer and affects its prognosis. (2)

A leading cause of cancer death in the United States is colorectal cancer. While studies have not corroborated a link between dietary fiber and colorectal cancer, a link has been suggested between rice consumption and colorectal cancer risk. In one study, rice consumption was associated with a decreased risk of colorectal cancer while high consumption of non-rice cereals was linked to increased risk. (3) And in a large study known as the Adventist Health Study, consumption of brown rice at least once a week reduced the risk of developing colorectal polyps (a precursor to colon cancer) by forty percent. (4)

Alleviate symptoms of Crohn's disease. Crohn's disease is characterized by chronic inflammation of the intestines. Although the cause of the disease is unclear, it is believed that dietary fat aggravates the inflammation. One small study involved eleven people with inactive Crohn's disease who were given a mixture of the water-insoluble dietary fiber chitosan and vitamin C. This mixture significantly increased bowel movements and the fat content of feces during the treatment without exacerbating the activity of the disease. Chitosan was given in a dose of 1.05 grams per day for eight weeks. (5)

Reduce risk factors for type II diabetes and metabolic syndrome. Metabolic syndrome is a combination of disorders including hyperglycemia (high blood sugar), dyslipidemia (disruption of blood lipid levels), insulin resistance, obesity, and hypertension. Individuals with metabolic syndrome are at high risk for developing type II diabetes and heart disease. One study showed adding psyllium fiber to a normal diet reduced the risk for metabolic syndrome in overweight and obese individuals. However, the greatest improvements were seen when psyllium was combined with a high-fiber diet. (6) Other studies indicate psyllium may lower total cholesterol levels and increase HDL ("good") cholesterol levels while dietary fiber in general may lower blood pressure, inflammation, and glucose levels and benefit weight loss. (7) Additionally, studies suggest that soluble fiber may lower hemoglobin A1C levels, blood insulin levels, and cardiovascular risk factors in individuals with type II diabetes. (8) In addition to fiber, native banana starch may benefit diabetes. Native banana starch is a type of resistant starch found in green unripe bananas. Resistant starches resist digestion in the small intestine--where most digestion occurs—and go straight to the large bowel. In one study, individuals with type II diabetes who were obese had lower insulin levels and lost weight while supplementing with native banana starch. (9)

Prevent diverticulitis. Diverticulitis is a disorder in which small bulging pouches in the digestive tract become inflamed or infected and cause severe pain, fever, nausea, and changes in bowel habits. Although the cause of diverticulitis is unclear, it has been associated with a diet low in fiber. While dietary fiber may prevent the development of the diverticular pouches, it is not clear if supplementing with fiber has any benefit on the symptoms of diverticulitis. (10, 11)

Benefit heart disease. Studies have associated dietary fiber intake with reduced risk of heart disease. In one study of individuals considered at high risk for developing heart disease, increased dietary fiber through vegetables, fruit, and legumes was associated with lower glucose and total cholesterol levels and increased HDL (“good”) cholesterol levels. (12) In another study, individuals with mild to moderately elevated cholesterol levels received fourteen grams per day of soluble fiber in the form of psyllium for eight weeks. Psyllium reduced LDL ("bad") cholesterol levels, triglycerides, systolic blood pressure, and insulin resistance. (13) The herb Cassia tora (also known as Senna) decreases LDL cholesterol levels and triglyceride levels. (14) Since studies show soluble fiber benefits lipid levels, a recent study was done to determine if insoluble fiber has the same benefits. In a small study of eighty-eight individuals with elevated cholesterol levels, insoluble fiber rich in polyphenols reduced total cholesterol by 17.8 percent, LDL cholesterol by 22.5 percent, and triglycerides by 16.3 percent. (15)

Fructooligosaccharides are a group of complex carbohydrates that may also benefit heart disease. These are alternative sweeteners that occur naturally in plants such as artichoke, asparagus, banana, chicory, garlic, onion and many others. Fructooligosaccharides are calorie-free, do not cause tooth decay, and are considered soluble fiber. They are known to decrease cholesterol and triglycerides. (16)

Assist in weight management. Recent findings suggest solid carbohydrates produce more satiety than liquid carbohydrates and may help with weight management by producing the feeling of fullness. However, studies are inconclusive concerning the effects of dietary fiber and whole grains on satiety. (17)


  • plants
  • animal meat
  • whole grains (breads, pasta, rice, cereal, potatoes, bran)
  • tablets
  • capsules
  • powder

Dosage Information

The American Heart Association recommends an intake of 25 grams per day of dietary fiber preferably from foods rather than supplements. Read the ingredient list on labels to determine the source and amount of dietary fiber in food. Oats have the highest proportion of soluble fiber of any grain while whole-wheat breads and cereals are high in insoluble fiber. (18) 

Guidelines for Use

The United States Department of Agriculture (USDA) 2011 Guidelines suggest half of all daily grains should be whole grains. (19)

General Interaction

Consumption of some carbohydrates may affect blood sugar levels

Possible Side Effects

  • Excess dietary fiber can cause flatulence and bloating.

  • Excess starch is converted to fat and can cause weight gain.

  • Excess glycogen is converted to fat and can cause weight gain.


Glycogen is depleted during exercise and should be replaced with carbohydrates and protein.


1. Zhang CX, Ho SC, Cheng SZ, Chen YM, Fu JH, Lin FY. Effect of dietary fiber intake on breast cancer risk according to estrogen and progesterone receptor status. Eur J Clin Nutr. 2011 May 4. [Epub ahead of print]
2. Villaseñor A, Ambs A, Ballard-Barbash R, Baumgartner KB, McTiernan A, Ulrich CM, Neuhouser ML. Dietary fiber is associated with circulating concentrations of C-reactive protein in breast cancer survivors: the HEAL study. Breast Cancer Res Treat. 2011 Apr 1. [Epub ahead of print]
3. Uchida K, Kono S, Yin G, Toyomura K, Nagano J, Mizoue T, Mibu R, Tanaka M, Kakeji Y, Maehara Y, Okamura T, Ikejiri K, Futami K, Maekawa T, Yasunami Y, Takenaka K, Ichimiya H, Terasaka R. Dietary fiber, source foods and colorectal cancer risk: the Fukuoka Colorectal Cancer Study. Scand J Gastroenterol. 2010 Oct;45(10):1223-31.
4. Tantamango YM, Knutsen SF, Beeson WL, Fraser G, Sabate J. Foods and Food Groups Associated With the Incidence of Colorectal Polyps: The Adventist Health Study. Nutr Cancer. 2011 May 4:1. [Epub ahead of print]
5. Tsujikawa T, Kanauchi O, Andoh A, Saotome T, Sasaki M, Fujiyama Y, Bamba T. Supplement of a chitosan and ascorbic acid mixture for Crohn's disease: a pilot study. Nutrition. 2003 Feb;19(2):137-9.
6. Pal S, Khossousi A, Binns C, Dhaliwal S, Ellis V. The effect of a fibre supplement compared to a healthy diet on body composition, lipids, glucose, insulin and other metabolic syndrome risk factors in overweight and obese individuals. Br J Nutr. 2011 Jan;105(1):90-100.
7. Giacosa A, Rondanelli M. The right fiber for the right disease: an update on the psyllium seed husk and the metabolic syndrome. J Clin Gastroenterol. 2010 Sep;44 Suppl 1:S58-60.
8. Vuksan V, Rogovik AL, Jovanovski E, Jenkins AL. Fiber facts: benefits and recommendations for individuals with type 2 diabetes. Curr Diab Rep. 2009 Oct;9(5):405-11.
9. Ble-Castillo JL, Aparicio-Trápala MA, Francisco-Luria MU, Córdova-Uscanga R, Rodríguez-Hernández A, Méndez JD, Díaz-Zagoya JC. Effects of native banana starch supplementation on body weight and insulin sensitivity in obese type 2 diabetics. Int J Environ Res Public Health. 2010 May;7(5):1953-62.
10. Janes SE, Meagher A, Frizelle FA. Management of diverticulitis. BMJ. 2006 Feb 4;332(7536):271-5.
11. Petruzziello L, Iacopini F, Bulajic M, Shah S, Costamagna G. Review article: uncomplicated diverticular disease of the colon. Aliment Pharmacol Ther. 2006 May 15;23(10):1379-91.
12. Estruch R, Martínez-González MA, Corella D, Basora-Gallisá J, Ruiz-Gutiérrez V, Covas MI, Fiol M, Gómez-Gracia E, López-Sabater MC, Escoda R, Pena MA, Diez-Espino J, Lahoz C, Lapetra J, Sáez G, Ros E; PREDIMED Study Investigators. Effects of dietary fibre intake on risk factors for cardiovascular disease in subjects at high risk. J Epidemiol Community Health. 2009 Jul;63(7):582-8.
13. Solà R, Bruckert E, Valls RM, Narejos S, Luque X, Castro-Cabezas M, Doménech G, Torres F, Heras M, Farrés X, Vaquer JV, Martínez JM, Almaraz MC, Anguera A. Soluble fibre (Plantago ovata husk) reduces plasma low-density lipoprotein (LDL) cholesterol, triglycerides, insulin, oxidised LDL and systolic blood pressure in hypercholesterolaemic patients: A randomised trial. Atherosclerosis. 2010 Aug;211(2):630-7. Epub 2010 Mar 17.
14. Cho SH, Kim TH, Lee NH, Son HS, Cho IJ, Ha TY. Effects of Cassia tora fiber supplement on serum lipids in Korean diabetic patients. J Med Food. 2005 Fall;8(3):311-8.
15. Ruiz-Roso B, Quintela JC, de la Fuente E, Haya J, Pérez-Olleros L. Insoluble carob fiber rich in polyphenols lowers total and LDL cholesterol in hypercholesterolemic sujects. Plant Foods Hum Nutr. 2010 Mar;65(1):50-6.
16. Sabater-Molina M, Larqué E, Torrella F, Zamora S. Dietary fructooligosaccharides and potential benefits on health. J Physiol Biochem. 2009 Sep;65(3):315-28.
17. Pan A, Hu FB. Effects of carbohydrates on satiety: differences between liquid and solid food. Curr Opin Clin Nutr Metab Care. 2011 Apr 23. [Epub ahead of print].
18. American Heart Association. Available at May 15, 2011.
19. United States Department of Agriculture-2011 Nutritional Guidelines. Available at Accessed May 15, 2011.

Evidence Based Rating Scale

The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies and what our clinical advisors have found to be efficacious in their personal practice into a visual and easy to interpret format. This tool is meant to simplify the information on supplements and therapies that demonstrate promise in the treatment of certain conditions.








A high fiber diet may reduce risk of breast and colorectal cancers and reduce inflammation in breast cancer survivors. (1-4)

Crohn's Disease  
One small study showed chitosan with vitamin C alleviated symptoms without exacerbating the disease. (5)
Studies suggest fiber and banana starch lower insulin levels and hemoglobin A1c levels in individuals with type II diabetes. (8-9)

Heart Disease Prevention  
Numerous studies indicate complex carbohydrates reduce risk of heart disease through many factors including reducing LDL, triglycerides, systolic blood pressure, and insulin resistance. (12-16)
High Cholesterol  
Numerous studies indicate complex carbohydrates increase HDL, and reduce LDL and triglycerides. (12-16)
Metabolic Syndrome  
Studies indicate fiber lowers blood pressure, cholesterol, inflammation, glucose levels; increases HDL cholesterol and benefits weight loss. (6-7)

Weight Management  
Solid carbohydrates produce satiety but studies are inconclusive for fiber and whole grains. (17)

Date Published: 05/22/2011
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