Originally published August 2022. Updated September 2026 with a precise definition, a types table, and current citations.
Introduction
Most people who search what are polysaccharides want a precise definition first. Polysaccharides are large carbohydrates built from many simple sugars (i.e., monosaccharides) linked together by chemical bonds called glycosidic bonds. Starch, cellulose, glycogen, and the beta-glucans in oats are all polysaccharides. They differ in which sugars they contain and how those sugars are linked, and that difference decides what they do in your body. In this article, I explain the main types, where they occur in food, and what clinical research has measured, including my own trials. I also explain why some polysaccharides are rare in the modern diet.
What Are Polysaccharides? A Precise Definition
The short answer to what polysaccharides are is that they are sugar chains long enough to count as large molecules. A single sugar unit, such as glucose or fructose, is a monosaccharide. Two joined units, such as the sucrose in table sugar, form a disaccharide. Short chains of a few units (3-10) are oligosaccharides, and long chains of many units (hundreds to thousands) are polysaccharides.
The links between those units are glycosidic bonds (i.e., the chemical attachment that joins one sugar to the next). A standard glycobiology text defines polysaccharides as large glycans built from repeating sugar motifs (Varki & Kornfeld, 2022). The type of bond matters as much as the sugar itself. Starch and cellulose are both chains of glucose, yet your body digests one and cannot digest the other.
That single contrast explains why I often say that a sugar is not a sugar. Two molecules built from identical units can behave in completely separate ways. The table below answers what polysaccharides are in practical terms, with examples of polysaccharides you already eat.
| Polysaccharide | Built from | Key role in nature | Where you get it |
|---|---|---|---|
| Starch | Glucose | Energy storage in plants | Potatoes, rice, wheat, corn, beans; digested for energy |
| Glycogen | Glucose | Energy storage in animals | Made and stored by your own liver and muscles |
| Cellulose | Glucose | Structure of plant cell walls | Vegetables and whole grains; insoluble fiber you cannot digest |
| Chitin | N-acetylglucosamine | Structure of shells and fungal walls | Crustacean shells, insects, mushrooms |
| Beta-glucans | Glucose | Cell wall material | Oats, barley, mushrooms, yeast; soluble fiber |
| Pectin | Mainly galacturonic acid | Cell wall material in fruit | Apples, citrus peel; soluble fiber |
| Acemannan | Mannose, partly acetylated | Carbohydrate of aloe inner gel | Aloe vera gel and standardized aloe powders |
General chemistry drawn from Varki and Kornfeld (2022) and standard biochemistry references.
Types of Polysaccharides and What They Do
Scientists sort polysaccharides into two broad groups by job. Storage polysaccharides, such as starch and glycogen, hold glucose in a compact form until a cell needs energy. Structural polysaccharides, such as cellulose and chitin, give plants, fungi, and shellfish their shape and strength.
That split answers a common question about why starch is a reliable source of energy. Enzymes in your saliva and small intestine break the bonds in starch and release glucose for fuel. Your body stores surplus glucose as glycogen in the liver and muscles, which is the same strategy in animal form.
Structural polysaccharides pass through the small intestine largely intact because human enzymes cannot break their bonds. Many of them reach the colon as dietary fiber, where gut bacteria ferment some types into short-chain fatty acids. So when people ask what polysaccharides do, the honest answer depends entirely on which polysaccharide they mean.
Polysaccharides in Food: Common Sources and Rare Ones
Most polysaccharides in food come packaged as complex carbohydrates in whole plants. Whole grains, beans, lentils, vegetables, fruit, and mushrooms supply starch alongside several kinds of fiber. A refined diet built on white flour and sugar supplies mostly starch and simple sugars instead.
Some polysaccharides are rare in almost anyone’s diet. My own research has focused on polysaccharides from two sources, aloe vera and rice bran, and neither shows up much on an ordinary plate. I have yet to meet anyone who eats aloe vera with dinner. I describe the aloe molecules in detail in my article on aloe polysaccharides.
Rice bran is the outer layer removed when brown rice is polished into white rice. Most people therefore eat extraordinarily little of it, even when rice is a staple. I cover its nutrients in stabilized rice bran. Not every product I make relies on polysaccharides, such as my Curcumin product, which I discuss in the article on tetrahydrocurcumin vs curcumin.
What Clinical Research Shows About Dietary Polysaccharides
The strongest human evidence concerns polysaccharides eaten as dietary fiber. A Lancet series of systematic reviews pooled 185 prospective studies and 58 clinical trials with 4,635 adult participants (Reynolds et al., 2019). In those observational data, those consuming the most amount of fiber had 15 to 30 percent lower all-cause and cardiovascular mortality than those who consumed the lowest amount.
Those observational figures show association, not proof of cause. In the clinical trials within that same Lancet series, higher fiber intakes produced significantly lower body weight, systolic blood pressure, and total cholesterol in adults. The researchers found the largest risk reductions at 25 to 29 grams of fiber per day (Reynolds et al., 2019).
One specific polysaccharide has especially clean trial data. Across 28 randomized trials in adults, at least 3 grams daily of oat beta-glucan lowered LDL cholesterol compared with a control (Whitehead et al., 2014). The average reduction in those adults was 0.25 millimoles per liter. Across those trials, HDL cholesterol and triglycerides stayed statistically flat.
What My Own Polysaccharide Trials Measured
I will state the limits of my own work before the findings. Our clinical trial in Alzheimer’s disease was not placebo-controlled or blinded, and it included 34 subjects (Lewis et al., 2013). Every subject who took our formula (four teaspoons daily) already had a diagnosis, so none of these results can be read as findings in healthy adults. Cognitive test scores in those adults were significantly better than baseline by months 9 and 12, and several inflammatory and immune markers decreased. An uncontrolled design like that cannot establish cause, so I read these results as signals rather than proof.
From the data from the same study, we examined immune balance in more detail (Lewis et al., 2023). The subjects’ Th1/Th2 ratios started higher than those of healthy adults at baseline, and five of six measured ratios decreased over the year. I explain what that measure means in the Th1/Th2 ratio.
Every paper from that study appears on my page, the published research behind Daily Brain Care. That page lets you judge the evidence directly rather than through my summary.
Where Polysaccharides Fit in My Own Routine
I have eaten a whole-food, plant-based diet since 1999, which includes a lot of complex carbohydrates. Whole grains, beans, and vegetables deliver starch and fiber in the form the Lancet data describe. I train daily without drugs, and that training runs on the glucose those foods supply.
Food does not easily supply the aloe and rice bran polysaccharides I have spent years studying. That gap is the reason Daily Brain Care exists, and I use it daily myself. Knowing what are polysaccharides and which ones are missing from your plate are the first steps toward making a sensible choice.
I would rather you understand the chemistry than simply trust a label, and that conviction runs through my philosophy at Dr Lewis Nutrition®. Whether polysaccharides are good for you depends on which ones, in what form, and in what amount.
Conclusion
So, what are polysaccharides? They are long chains of simple sugars joined by glycosidic bonds, and bond type decides whether they fuel you or pass through as fiber. The best human evidence supports eating polysaccharide-rich whole foods, while research on rarer types such as aloe polysaccharides remains smaller and earlier. If you want those rarer polysaccharides alongside a whole-food diet, Daily Brain Care was designed to supply them.
Frequently Asked Questions
What are polysaccharides?
Polysaccharides are large carbohydrates made of many simple sugars linked by glycosidic bonds. Starch, glycogen, cellulose, chitin, pectin, and beta-glucans are common examples of polysaccharides. They differ in their building blocks and bond types.
What do polysaccharides do for the body?
Storage polysaccharides such as starch are digested into glucose for energy. Structural polysaccharides such as cellulose pass through as fiber, and gut bacteria ferment some types into short-chain fatty acids. The effect depends on the specific polysaccharide.
What is the most common polysaccharide?
Cellulose, the material of plant cell walls, is the most abundant polysaccharide in nature. Starch is the most common digestible polysaccharide in the human diet. Both are chains of glucose joined by different bonds.
Why are polysaccharides a reliable source of energy?
Starch packs many glucose units into a compact molecule. Digestive enzymes release that glucose gradually, and your body stores any surplus as glycogen. Fiber polysaccharides supply little direct energy because human enzymes cannot break their bonds.
Are polysaccharides the same as sugar?
Polysaccharides are built from sugars, but they are different from table sugar. Sucrose is a disaccharide of just two units, while polysaccharides contain many. That structural difference changes how quickly and how completely your body uses them.
References
Lewis, J. E., McDaniel, H. R., Agronin, M. E., Loewenstein, D. A., Riveros, J., Mestre, R., Martinez, M., Colina, N., Abreu, D., Konefal, J., Woolger, J. M., & Ali, K. H. (2013). The effect of an aloe polymannose multinutrient complex on cognitive and immune functioning in Alzheimer’s disease. Journal of Alzheimer’s Disease, 33(2), 393–406. https://doi.org/10.3233/JAD-2012-121381
Lewis, J. E., McDaniel, H. R., Woolger, J. M., & Khan, S. A. (2023). The characterization of the Th1/Th2 ratio in moderate-severe Alzheimer’s disease patients and its response to an aloe polymannose-based dietary supplement. Journal of Alzheimer’s Disease, 96(4), 1723–1737. https://doi.org/10.3233/JAD-230659
Reynolds, A., Mann, J., Cummings, J., Winter, N., Mete, E., & Te Morenga, L. (2019). Carbohydrate quality and human health: A series of systematic reviews and meta-analyses. The Lancet, 393(10170), 434–445. https://doi.org/10.1016/S0140-6736(18)31809-9
Varki, A., & Kornfeld, S. (2022). Historical background and overview. In A. Varki, R. D. Cummings, J. D. Esko, et al. (Eds.), Essentials of glycobiology (4th ed., Chapter 1). Cold Spring Harbor Laboratory Press. https://www.ncbi.nlm.nih.gov/books/NBK579927/
Whitehead, A., Beck, E. J., Tosh, S., & Wolever, T. M. (2014). Cholesterol-lowering effects of oat β-glucan: A meta-analysis of randomized controlled trials. The American Journal of Clinical Nutrition, 100(6), 1413–1421. https://doi.org/10.3945/ajcn.114.086108
