Prebiotics are indigestible nutrients that serve as food for probiotics. Since humans don’t digest prebiotics, these nutrients pass through the digestive system until they are fermented in the large intestine by bacteria. Prebiotics are what allow probiotics to thrive.
Besides being a food source for probiotics, prebiotics may have some health benefits of their own, including the following:
• Enhancing absorption of minerals, such as calcium, iron, and magnesium
• Promoting healthy bowel function and regularity
• Inhibiting growth of cancerous lesions in the digestive tract
• Improving the funtioning of the immune system
• Lowering blood cholesterol levels
There are many natural dietary sources of prebiotics. The following foods are especially good sources:
• Jerusalem artichoke
• Chicory root
• Wheat bran
Prebiotics may also be added to foods like cottage cheese, yogurt, yogurt drinks, cereals, granola bars, and pasta. Food ingredients that act as prebiotics — but may or may not be proclaimed as such — include the following:
• Inulin (don’t confuse this with insulin!), a type of fiber
• Fructooligosaccharides, which consist of connected sugars
• Galactooligosaccharides, which result from certain enzymes acting on lactose (“milk sugar”)
• Polydextrose, a synthetic type of fiber
• Maltodextrin, derived from corn, rice, or potato starch
• Lactulose, a synthetic indigestible sugar
• Resistant starch, called this because it resists digestion (found naturally in cooked and cooled starchy foods such as pasta salad)
Like probiotics, prebiotics are available as supplements, usually in capsule or powder form. These supplements most commonly contain inulin, chicory root extract, polydextrose, or oligosaccharides. It’s probably best, though, to get your prebiotics from natural food sources, since many of these foods contain fiber and other important nutrients. There is no established recommended daily level of consumption for prebiotics. Some studies suggest that aiming for 5–15 grams daily is a good idea; Americans actually get about 1–4 grams each day on average. Foods that contain added prebiotics usually provide 2–4 grams per serving.
Prebiotics are generally considered to be safe. Common side effects include gas, bloating, and cramps, especially if you suddenly increase your intake of prebiotics; it’s best to gradually increase your intake. Remember that while prebiotics themselves do not affect blood glucose level, if they’ve been added to a food that contains carbohydrate, they may slow or otherwise change the digestion of that food’s carbohydrate.
A win-win situation
Both probiotics and prebiotics play a vital role in sustaining good health. Whether through supplements or simply through dietary changes, you may find that adding these living organisms — and their food — to your diet ends up making you a happier organism, as well.