What comes to mind when you hear the word “starches,” or “starchy foods”? For most people, it’s probably processed food — especially bread products like dinner rolls, crackers, and cookies. But there are also many whole, unprocessed foods that are high in starch: rice, corn, quinoa, and potatoes, for example. In fact, most traditional human diets have been centered around starches.
While it’s true that cookies and quinoa both contain starch, they don’t affect the body in the same way. If your idea of starches is only based on processed grains or fried potatoes, you may be surprised to learn that some starches are among the healthiest foods you can eat. In fact, some types of starch offer gut health benefits that can’t be achieved with any other food, making them important foods for a healthy life.
So, what are starches, exactly? Which types of starches are healthy and unhealthy, and how can you add more of the good ones to your diet?
Three types of carbohydrates are found in nature: sugar, fiber, and starches. This means that all starches are carbohydrates, but not all carbohydrates are starches. Sugar, for example, is a simple carbohydrate, while both fiber and starches are complex carbohydrates.
This doesn’t mean that all starches act like complex carbohydrates once we subject them to processing, though. Most cookies, white bread, and crackers (for example) typically get digested as rapidly — and spike blood glucose just as dramatically — as simple carbohydrates like table sugar.
But, let’s back up and talk about starches as they appear in the plants that contain them. These starches are natural compounds composed of long, branching chains of glucose (a sugar, and the primary source of energy for living cells). They’re produced in plants to serve as an energy source, helping plants survive when the climate is cold or dry. Starches are also an energy source for humans and other animals who then consume these plants further up the food chain.
When starches are digested, they’re broken down into glucose molecules with the help of digestive enzymes called amylases.
Different types of plants contain varying amounts of starch. For instance, plants that can photosynthesize easily thanks to a large leafy surface area and many hours of full sun tend to have less starch than plants that have to save energy for literal and figurative rainy days.
As you’ll see, it has plenty of reason to brag.
Undigested carbohydrates, including resistant starch, are prebiotics that ferment and turn into food for the good bacteria in your digestive system. Eating resistant starch boosts the population of these beneficial bugs, which are commonly called probiotics. So fortified, these good critters crowd out the bad ones, making for a happier gut (and a healthier gut owner).
Eating resistant starch helps to heal gut issues while preventing the development of a leaky gut that could otherwise drive food allergies, inflammation, and weight gain.
The positive change that resistant starch brings about in your gut microbiota may even translate to benefits for kidney health. Studies have shown that starch helps those with chronic kidney disease reduce inflammatory and toxic biomarkers in their plasma. Starch increases the number of good bacteria, strengthening the epithelial lining and outcompeting bacteria that produce harmful metabolites. Thus, fewer inflammatory agents are able to reach the bloodstream and cause issues for those with compromised kidneys.
Research shows that in humans, consumption of starch increases insulin sensitivity. This makes sense, as we’ve already seen that its lower digestibility leads to a decreased release of glucose into the bloodstream.
The metabolic benefits of dietary starch, especially in terms of improvements in insulin processing, occur independently of your gut microbiota. In one study, 15–30 grams (about 2–4 tablespoons) of potato starch per day improved insulin sensitivity and fat loss in obese men.
Some researchers suggest that starch may help to prevent or treat obesity. How? Starch is low in digestible calories. Low-caloric-density eating has been shown to be a sustainable approach to weight loss, since dieters may feel less deprived with a higher volume of food.
Furthermore, starch can work on a metabolic level to help reduce fat accumulation through its influence on gut bacteria and lipid metabolism.
A high cholesterol level and, in particular, a high ratio of LDL “bad” cholesterol to HDL “good” cholesterol, is a risk factor for developing heart disease.
But a 2018 meta-analysis (including 20 trials and published in Nutrition Research) showed that resistant starch was able to lower LDL cholesterol. Researchers found that adding resistant starch to subjects’ diets optimized triglyceride and cholesterol levels while decreasing fat mass. The effects were found to be most prominent when people ate at least 20 grams of RS per day, and did so for at least 4 weeks.
Starches and starchy foods often get a bad rap, but, like carbohydrates in general, not all starches are unhealthy. Starches that are slowly digested (or not digested at all, in the case of resistant starch) can be beneficial for health and disease prevention, especially by supporting your gut health. While there is no official recommended daily intake for resistant starch, many people might benefit from including more of it in a healthy, balanced diet — especially when it comes to digestive health, and the prevention of diabetes and obesity.