EDUCATION


The Story of Sugar & Starch
The Story of Sugar and Starch

What They Are and What the Experts Say

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ith diabetes, heart disease and obesity being a problem these days, plenty is being said about sugar and carbohydrates. Sometimes, the terms are used interchangeably and this is when we get confused. Is sugar bad for you? Are carbohydrates bad for you? Aren’t they the same thing? If they are, how come some carbohydrates like rice don’t taste sweet?

Answering these questions requires understanding the basics – which is why we’ve decided to clarify once and for all how rice, carbohydrates and sugar are related to each other as well as what the experts have to say about them.

So let’s start with carbohydrates. Our bodies require carbohydrates because they are our main source of energy. According to the United States Department of Agriculture (USDA), 45% to 65% of our calories should come from carbohydrates (1). Proteins and fats provide calories too but comparatively, carbohydrates are the ones that are more easily broken down by the body for energy (2). Besides that, carbohydrates are also important for a whole list of functions: for example, to maintain in smooth working order our heart, our muscles, our central nervous system and so many of our other organs.

If carbohydrates are so essential, why then is it getting a bad reputation? One of the reasons carbohydrates get the blame for diabetes and heart ailments is the fact that we tend to consume this nutrient in excess. More importantly, we fail to consider the types of carbohydrates we’re taking into our bodies.

This is where sugar comes in. Sugar is a type of carbohydrate and can be further divided into simple sugars and complex sugars. Examples of simple sugars include fructose, sucrose and glucose. We can find fructose in fruits while sucrose is the table sugar that we sometimes use to season our food and add to our drinks. Both fructose and sucrose are broken down by our bodies into glucose – our source of energy.

What about complex sugars? Complex sugars include rice, pastas, potatoes and also grains. These are also known as starch. Starch usually doesn’t taste quite as sweet as simple sugars which is why we don’t really think of “sweet” when we’re eating rice or pastas. Be assured, however, that our bodies break down complex sugars such as starch into glucose; just like they do with the simple sugars.

But if both simple sugars and starches are broken down into glucose, how is it that some starches have a stellar reputation (grains are always good for you, says mom), some get a bad name (watch the rice and pasta, warns well-meaning friends) and simple sugars are just considered villains?

The answer comes down to how fast the body breaks down these sugars (or carbohydrates) and gets them into our bloodstream. This is such an important factor that we now have an index, called the glycemic index (GI), to measure this. Low GI foods would be foods slowly broken down by the body so that the sugar gets into our system gradually, whilst high GI foods are exactly the opposite.

Simple sugars are usually high GI foods. They are easily broken down by the body and quickly get into the bloodstream, causing spikes in the body’s blood sugar level. Our bodies then respond to this spike by releasing a flood of insulin which, to put it simply, transports this glucose from the bloodstream into our cells where the glucose is converted to energy. The problem arises when so much insulin is released; our body thinks we’ve got too much glucose and stores this as fat to be burned off later. And here comes the really bad part: because there’s a lot of insulin in the bloodstream, the glucose depletion happens pretty fast. This results in our blood sugar level dropping drastically and suddenly. When that happens, we feel lethargic and hungry. So what do most of us do? We reach for the sugary foods again!

Do we then avoid simple sugars and just stick to complex sugars or starches? Well, while starches do not break down as easily as simple sugars, different types of starches do get digested faster than others. The former is often called rapidly digestible starch (RDS) whilst the latter is termed slowly digestible starch (SDS).

As we’ve seen in the case of simple sugars, the faster our sugar is digested, the more likely it is to have an adverse effect on our body, so it makes sense to stick to SDS. Most starches aren’t simply just RDS or SDS, though; foods are typically a combination of both. Rice, for instance, is a combination of amylose and amylopectin. Different types of rice would have different amylose-to-amylopectin ratios and one could say the same thing too about other starches such as pasta.

The smart move then would be to stick to foods with a higher amylose-to-amylopectin ratio because these would promote slower digestion and the more gradual release of glucose into the bloodstream. A report by the Food and Agriculture Organization of the United Nations (FAO) (2) states the following:

“Slow digestion and absorption of carbohydrates helps to maintain steady blood glucose levels which can be beneficial to diabetics.” 

The same report goes on to include this too, indicating support for the fact that amylose is an SDS:

“High-amylose starches are associated with a lower glycemic response than low-amylose starches, and they may also empty more slowly from the stomach.”

Keeping to our rice example, then, we would want to go with rice containing a higher amylose-to-amylopectin ratio because it has a lower GI index, allowing for steadier blood sugar levels and longer satiety. One could try, for instance, oats or ragi since both have a low GI index and are often viewed as “healthy” grains. But in case you are typically Asian and rice is your primary choice, then there’s always the Grayns rice cooker where the RDS is drained away so that the GI of the rice is lowered, regardless of what type of rice one starts off with. For more information on the Grayns rice cooker and a healthier way of cooking rice, do click on the following link: SCIENCE OF COOKING RICE


References:
  1. United States Department of Agriculture National Agriculture Library. (2005). Dietary Reference Intakes for Energy, Carbohydrates, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Retrieved from http://fnic.nal.usda.gov/dietary-guidance/dri-nutrient-reports/energy-carbohydrate-fiber-fat-fatty-acids-cholesterol-protein#overlay-context=dietary-guidance/dietary-reference-intakes/dri-reports
  2. McKinley Health Center, University of Illinois at Urbana-Champaign. (2014). Macronutrients: The Importance of Carbohydrate, Protein, and Fat. Retrieved from http://www.mckinley.illinois.edu/handouts/macronutrients.htm
  3. Food and Agriculture Organization of the United Nations (FAO). (1998). Carbohydrates in Human Nutrition: Report of a Joint FAO/WHO Expert Consultation, Rome, 14 – 18 April 1997, Issue 66, p. 98. ISSN 0254-4725