October 2003 - Carbs 101

We get calories in three forms - fats, proteins, and carbohydrates. Carbohydrates come strictly from plant sources, and until very recently were considered quite innocuous unless you had diabetes. We're now learning that the truth is not so simple.

A Brief History

For thousands of years, humans lived in hunter-gatherer societies. The foods we ate were those that could be hunted or gathered that day. The carbohydrates consumed consisted of fresh fruits, vegetables, nuts, and sprouts. Virtually none of them came from grains or simple sugars.

Around 9000 years ago someone in Iraq apparently invented the plow, and the Agricultural Revolution was born. Grains were the earliest crops grown. This stone-ground, calorie-dense, inexpensive food allowed populations and cities to grow, and (we know from archeological records) also caused humans to become much smaller. Many people often had little more than bread or porridge to eat, and got very little protein.

150 years ago another big change in society, the Industrial Revolution, occurred. As machinery was put to use to produce crops, food (especially wheat, corn, oats, and various other grains) became even less expensive. The grains we ate also became much more processed. The bran and the germ were typically removed, and the flour was crushed to a fine powder under steel rollers, resulting in a soft white bread with an extended shelf life.

Further dietary changes have occured in the past 20 years, as we were given the message that fat is bad, and carbs are good. The USDA 's Food Guide Pyramid urges us to eat more servings from the Bread, Cereal, Rice, and Pasta group (6 - 11 per day) than any other category of food, promising us in return a longer healthier life. Society has responded to this message (with many people downing handfuls of Snackwell Fat-free Cookies in the mistaken notion that this would help them lose weight) to the point that today 78% of the carbohydrates we eat come in the form of sugar, corn syrup, breads, pastas, crackers, chips, rice, cereal, and other starches.

Carbohydrates and the Glycemic Index

Carbohydrate is another name for "sugar". It can come in the form of a sweet simple sugar such as fructose or sucrose (table sugar). Or it can be a "complex carbohydrate", which is a molecule that is made up of a string of simple sugars all connected together. When you eat any carbohydrate, your body breaks it down into simple sugars and then insulin is used to move those simple sugars into the cells of your body.

The "glycemic index" is a measurement of how quickly a carbohydrate is digested and releases its sugar molecules into your bloodstream. Foods with a high glycemic index quickly release a lot of sugar molecules into the bloodstream, and also result in an insulin spike , which serves to move those large amounts of sugars into cells . The glycemic index multiplied by the number of calories in a food gives the "glycemic load", indicating the total relative rise in blood sugar for a given food.

So What's the Problem?

Accompanying the dramatic changes in our diet has been an equally dramatic rise in cardiovascular disease, diabetes, arthritis, senility, and other degenerative diseases. Though the blame can't all be pinned here, there are no doubt some connections.

The spike in insulin after a high-glycemic meal causes blood sugar levels to drop below normal a couple hours later, before eventually returning to normal. This drop in blood sugar then causes fatigue and hunger. A coffee-doughnut break will temporarily take care of that problem, but only causes the cycle to repeat. Studies have shown that people are much more hungry at the meal following a high-glycemic meal, and and that they have a more difficult time losing weight when eating high glycemic index foods.

The body has a very limited ability to store carbohydrates. The liver stores what it can hold, and the rest is converted to fat. So high glycemic foods tend to raise the fats, also known as triglycerides, that are circulating in your blood, and lower HDL (good cholesterol) levels, increasing your risk for cardiovascular disease. So substituting white flour for fat might not be doing your heart any good.

Recent studies have also shown that eating too many high-glycemic index foods can increase the risk of type-2 diabetes. Excessive amounts of high-glycemic index foods can put pressure on the pancreas to increase insulin production. Eventually the cells of the body can become resistant to that insulin, and the person can end up with Syndrome X, and eventually diabetes.

What to eat

The numbers associated with the foods below are relative to glucose, which has a glycemic index of 100.

Though its difficult to predict the glycemic index of a food until its tested, there are some general rules of thumb. The easiest thing to remember is to pay attention to your consumption of "white" foods. White bread, white rice, white sugar, and white potatoes all raise blood sugar dramatically. Below are some additional guidelines for choosing low-glycemic foods:

• Fruits and vegetables. These are your healthiest carbohydrate options, with the majority having a low glycemic index.
  

• Lean meats and healthy fats. When it comes to healthy eating, cheap carbohydrates are often your worst choice. Protein and fats can both lower the glycemic response when eaten at a meal with carbohydrates.
  
  
• Strictly limit grains, and limit potatoes unless you are extremely active. Sweet potatoes are lower glycemic than white, and barley is lower glycemic than wheat.

Heart disease, diabetes, and other degenerative diseases rarely happen by chance. We cause them to happen by our lifestyle habits. Paying attention to the carbs you ingest can make a tremendous difference in your health and longevity.

This is a large topic to discuss in a brief forum like this, and there is still much to be learned about how carbohydrates affect the body. For more information, you can access a database of glycemic indexes from the American Journal of Clinical Nutrition at: http://www.centerfornaturopathic.com/Glycemic%20index.htm

Go Long,

Wiley