ASK DR. BETHBy Dr. Beth Prinz

The Confusing Realm of Carbohydrates

Starch, Sugar, Fiber: The Plant-Based Approach

Dr. Beth Prinz

Dear Food Doc,

What is the difference between carbohydrate, sugar, and dietary fiber, and why does it matter to my health? My Cheerios nutrition label divides carbohydrate into five categories: Total Carbohydrate, Dietary Fiber, Soluble Fiber, Sugars, and Other Carbohydrates. I’m confused.

— Carb Crazy in Ojai.

Dear Carb Crazy,

  I find the terminology confusing, too.  The former biochemistry student in me thinks it’s like labeling water as Total H20, Dietary Snowflakes, Melted Snowflakes, Water, and Other H20.  It’s little surprise if consumers are confused. We often hear the message “eat low carb,” yet all fruits and vegetables are composed mainly of carbohydrates and we know more of these in the diet is a good thing.

And what about starch? Although a major dietary staple, starch is not explicitly listed on the food label.  Consumers must deduce that starch is the unnamed carbohydrate, calculated by subtracting Dietary Fiber and Sugars from Total Carbohydrate. 

The fact is, sugar, dietary fiber, and starch are all carbohydrates.  Also called disaccharides and polysaccharides, these compounds have chemical similarities, but with key structural or chemical differences which translate into widely contrasting effects on our health.

As a nation, we over-consume sugar, and under-consume fiber. The United States Department of Agriculture tells us that Americans consume, on average, 150 to 170 pounds of refined sugar a year (we should be getting a maximum of 20 pounds per year, or 24 grams per day), yet only 3 percent of Americans are getting adequate amount of fiber in their diets (recommended 38 grams per day for men, 25 grams per day for women under age 50).  A whopping 97 percent of us are fiber deficient! 

Fiber deficiency comes with a heavy price in terms of health.  The incidence of varicose veins, acid reflux, constipation, hemorrhoids, diverticulosis, and, more importantly, obesity, colon cancer, and heart disease, are inversely related to the consumption of fiber.  Every additional 7 grams per day of total fiber consumed reduces risk of cardiovascular disease by 9 percent.

The consumption of processed sugars wreaks havoc in our bodies. Sucrose does not make it to the large intestine to feed our healthy bacteria. Instead, this small disaccharide is rapidly split into its constituent units — glucose and fructose — and these molecules readily cross our small intestine, flood into our bloodstream, and set off a cascade of hormonal and physiological responses. This scenario was nonexistent in nature before the advent of refined foods, but has become a routine part of our modern diet.

I think of starch as fuel for our cells, fiber as food for our microbes, and sugar as poison (refined sugar, in the quantities we consume today, is poisoning us slowly).

Starch is an ideal source of stored energy. Composed of bulky, branched-chains of glucose molecules connected by specific types of chemical bond that our digestive enzymes are equipped to handle (as opposed to dietary fiber cellulose which is nearly identical to starch except for a slight difference in the chemical bonds between the glucose molecules which renders it untouchable by our digestive enzyme amylase), starch requires several steps, by several different enzymes, in different parts of the digestive tract, before it is fully degraded to glucose and available for absorption into our bloodstream. This multi-step, delayed decomposition is what makes starch a physiologically more favorable carbohydrate than sucrose (sugar).

Indigestible carbohydrates are called fiber. Fiber is structurally diverse. There are hundreds of different types of fiber compounds found in thousands of different plants. This diversity feeds and sustains a variety of healthy bacteria in our colon. This is why we need to eat a variety of whole plants every day to get the necessary variety of fiber for optimal health. 

I think the term “low carb” is confusing and should be avoided. Maybe we should call it a “correct carb diet,” or, better yet, a whole-food, plant-based diet. After all, we don’t want to reduce all carbs, and the only way to increase fiber in our diet is to eat more carbs — of the whole plant variety.

Whole plants are a package deal. Starch and sugar are part of that deal. This needn’t concern us, however, because Mother Nature has a wonderful way of wrapping everything up in perfect proportions, with just the right amount of things that are very good for us — such as starch, fiber, protein, fat, and phytonutrients such as vitamins and antioxidants. When we eat whole-plant foods, the sugars are released from the food slowly, along with all the other nutritious components of the plant. Therefore, if we eat exclusively whole fruit and vegetables, and whole grains, legumes, seeds, and nuts, we can do so without concern about sugar content or weight gain. High-fiber content makes us feel full with much fewer calories. 

For those wishing to try a more plant-based approach to eating, and seeking inspiration, try Farmer & The Cook — my favorite dishes are the raw tacos and the Swiss Chard Enchilada with cashew cheese, or The Hip Vegan — you won’t believe that plant-based eating can taste this great.  The 3 Scoop Salad, (the scoops are a seed pate, a spicy almond pate, and hummus) or the Reuben sandwich made with grilled seitan, cheez, and sauerkraut are my personal favorites, but be sure to leave room for the delicious date shake — comes in four flavors.