Menu
Menu
Probiotics are beneficial bacteria that might help our gut. However, as mentioned in a previous blog post, many studies indicate that probiotics often don’t make a significant difference because our own gut bacteria dominate, rendering new incoming probiotics largely ineffective (1).
Prebiotics, on the other hand, serve as food for our gut bacteria and offer health benefits by promoting the growth and diversity of these bacteria. They must resist digestion, reach the gut intact, and be fermented by gut bacteria.
So, Is Prebiotic the Same as Fiber?
Although most prebiotics are fiber, not all fiber is prebiotic. Additionally, some non-fiber food substances, such as polyphenols and resistant starch, can also function as prebiotics.
Insoluble Fiber: This type passes through the digestive system mostly intact and acts as a bulking agent. It reaches the colon, attracts water to bulk up stools, and stimulates intestinal contractions, speeding up the passage of food and waste.
Soluble Fiber: Soluble fiber dissolves in water, forming a gel that softens stool, aiding smooth and comfortable passage.
Insoluble fiber is rarely utilized by gut bacteria and mostly gets excreted. Some soluble fibers have prebiotic properties, meaning our gut bacteria can ferment and break them down, producing beneficial metabolites like short-chain fatty acids (SCFAs) and vitamins (2). SCFAs nourish the gut lining, reduce inflammation, regulate immune function, improve insulin sensitivity, and aid in weight loss. Different plant foods contain varying proportions of soluble and insoluble fibers.
Some common prebiotic fibers and their sources include:
| Prebiotic fibers | Sources |
|---|---|
| Inulin and fructo-oligosaccharides (FOS) | Chicory root, Jerusalem artichoke, asparagus, onions, garlic, bananas |
| Beta-glucans | Oats, barley, wheat, mushrooms |
| Pectins | Citrus peels or the core and skins of fruits like apples and pears |
| Galactooligosaccharides (GOS) | Legumes, including lentils and chickpeas. |
Foods such as chicory root, Jerusalem artichokes, and asparagus are high in inulin and FOS but may not be commonly consumed in everyday diets. Instead, opt for more commonly eaten foods like onions, garlic, leeks, and bananas. While cooking onions and garlic can reduce their prebiotic content, even a small amount from natural food sources can make a significant difference to your gut health.
Inulin and FOS supplements are also widely available and can be considered. FOS is often used as a sweetener in health food products since it is about half as sweet as table sugar and calorie-free. For those using zero-calorie sweeteners, FOS is another option to try that can double as a prebiotic supplement. Since pectin is mostly derived from inedible parts of fruits, supplements like apple pectin can also be considered. However, unlike inulin and FOS, pectin thickens quickly, so be sure to drink plenty of water with it.
Some common non-fiber prebiotics and their sources include:
| Non-Fiber Prebiotics | Sources |
|---|---|
| Polyphenols | Tea, fruits, dark chocolate, nuts and seeds, red wine, olive oil |
| Resistant starch | Green banana, glass noodles, cooked and cooled starchy carbs like rice, pasta, bread and potatoes. |
Polyphenols, a category of plant compounds also known as phytonutrients, are easily obtained from various food sources. Over 8,000 types of polyphenols have been identified, which offer health-promoting effects such as antioxidant, anti-inflammatory, and neuroprotective properties. Emerging studies also highlight the positive relationship between polyphenols, gut microbiota, and the health benefits they provide (3).
Resistant starch, as the name suggests, resists digestion and functions similarly to soluble, fermentable fiber. Most carbohydrates in our diet contain some resistant starch, but the amount can increase in cooked rice, pasta, bread, and potatoes when they are cooled in the refrigerator—a process known as retrogradation. In addition to feeding our gut bacteria, resistant starch offers benefits such as improved insulin sensitivity, lower blood sugar levels, and various benefits for digestion (4).
Green bananas and glass noodles contain about 20-40% resistant starch, while most common starches like rice, pasta, and potatoes have only about 2-4% (5), so it's best to introduce them gradually and in small quantities to avoid stomach discomfort. Since green bananas may not appeal to everyone's taste, green banana flour is often preferred. Alternatively, consider trying a prebiotic blend, such as this product, which combines two prebiotic fibers (Jerusalem artichoke and acacia fiber) and a resistant starch (green banana flour).
Prebiotics are essential for maintaining a healthy gut microbiome and overall well-being. To achieve good gut health, it is important to incorporate a wide variety of prebiotic foods or supplements, as this supports both the growth and diversity of gut bacteria. Since prebiotics ferment in the gut and produce gas, it's best to introduce them slowly to your diet and monitor your body's reaction.
