The Carbohydrate Wars Lesson 5: From Field to Fork (Video)

The sources of carbohydrates that we find growing in nature—vegetables, fruits, nuts, seeds, grains, and beans—are all mixtures of sugars, complex starches made of long chains of sugars, and fiber. Our bodies have evolved to use these foods for nourishment and energy.

In nature, high-carb foods with little fiber or highly concentrated sugars are very rare.

In the grocery store, such foods are plentiful. How does that happen?

The simple answer is that on the way to the grocery store the fiber, vitamins and minerals were removed, simple sugars were added, cell structure was destroyed, and starches made of long carbohydrate chains were chopped up into short easily digestible chains. In other words, the food was processed.

There are three aspects of that processing that determine to a large degree how the food affects your blood sugar and insulin levels.

First is the addition of sugars. In some cases the sugar added is table sugar, also called sucrose. In many cases it’s something called high-fructose corn syrup.

To make corn syrup, you start with a corn kernel, and strip off the outer covering where the fiber and the vitamins are. That leaves the white inner material, pure digestible starch, which you grind up into a fine powder.

Being ground up, that starch is easily converted into glucose by industrial chemistry. But we’re not yet finished—quite a bit of that glucose is converted by further chemical action to fructose. That fluid mixture of glucose and fructose is called high fructose corn syrup.

High fructose corn syrup is cheap to make and easy to add to food, so you’ll find it in many processed and highly processed foods. It carries a double whammy – the glucose goes straight into your blood, and the fructose goes to your liver, where it may well be converted into fat that can clog up your liver cells and impact liver function in a way that increases insulin resistance. You can learn more about that in our video “How Does My Liver Get Fat?”.

High-fructose corn syrup has been a staple of the food processing industry since the 1970’s, but it’s not their only trick. There’s also the simple process of grinding grain into flour. The finer the flour, the more quickly it can be turned into glucose in your body. Over the past few centuries with the available of high power equipment, that flour can cheaply be ground extremely fine.

It doesn’t matter what kind of starch you started with, whether it’s a wheat, rice, spelt, or amaranth grain—when you grind it into extremely tiny pieces, you create a substance that much more rapidly turns into glucose.

Third, food processing often removes fiber. A serving of applesauce, for example, has less than half the fiber of an apple. When you eat food that has its natural fiber, the fiber tends to slow down the rate of digestion, and therefore the rate at which other starches and sugars raise your blood glucose level.

Once it was recognized that fiber in food is vital to health, food manufacturers started adding to fiber back into the food to make their labels look better. The labels do look better, but they are misleading, since that added fiber is not all bound up with the starches and sugars in such a way as to slow down their digestion, which means there’s no real benefit in terms of effect on blood sugar.

The most important knowledge to take away is that carbs that start out in a field and end up on your fork can take many different forms. And whether a food is low carb or high carb is much less important than what’s been done to the carbohydrate, and the impact of that action on the relative amounts of sugars, starch, and fiber.

Having that understanding prepares you for the next and final lesson in this course.