Carbohydrates

Carbohydrates, literally, consist of organic molecules in which water (H₂O) have been added to carbon (C) to produce molecular fragments with the formula C(OH)H. The most common carbohydrates are sugars, starches, and fiber.

Plants are rich sources of carbohydrates, and carbohydrates are an important source of energy for humans. But in a larger context, carbohydrates are an important part of "the circle of life." Plants, through the process of photosynthesis combine the energy of the sun with carbon dioxide (CO₂) and water (H₂O) to produce carbohydrates (C(OH)H) and oxygen (O₂). In turn, animals (including humans) "burn" carbohydrates using oxygen (O₂) to produce energy, CO₂ and water (H₂O). In this context, (CO₂) is a necessary "plant food" and not a dangerous "green house gas."

Most carbohydrates of nutritional significance consist of chains of 5 or 6 C(OH)H fragments joined into a ring, where one of the C(OH)H fragments is further oxidized to form a C=O fragment (aldehyde or ketone) as part of a ring structure.

Common carbohydrates include:

• Ribose (5 carbon chain - building block of DNA and RNA)
• Glucose (6 carbon chain - most important sugar in the body)
• Fructose (6 carbon chain - mainly found in plants)
• Galactose (6 carbon chain - mainly found in milk)
• Sucrose ("table sugar" - combination of glucose + fructose)
• Lactose ("milk sugar" - combination of glucose + galactose)
• Starch (combination of many molecules of glucose; humans can digest)
• Fiber (combination of many molecules of glucose; humans cannot digest but bacteria and termites can)
  • Insoluble fiber (feeds good bacteria in the gut and reduces constipation)
  • Soluble Fiber (feeds good bacteria in the gut and reduces diarhhea)

Glycemic Index

For the purposes of dietary analysis and planning, the concept of Glycemic Index (GI) is useful. The GI of a food is determined by feeding healthy individuals a measured amount of a carbohydrate-containing food, and then measuring how high their blood glucose level goes. Pure glucose enters the blood very rapidly, and is assigned a glycemic index value of 100; most foods are absorbed less rapidly, and have lower GI values. A GI value of 0 denotes no rise in blood glucose.

According to [Mayo], we can score the glycemic index of common foods as:

• Low GI (1 to 55): Green vegetables, most fruits, raw carrots, kidney beans, chickpeas and lentils.
• Medium GI (56 to 69): Sweet corn, bananas, raw pineapple, raisins, cherries, oat breakfast cereals, and multigrain, whole-grain wheat or rye bread
• High GI (70 and higher): White rice, white bread and potatoes

Generally speaking, the terms "Low GI" and "Complex Carbs" are synnonymous, and likewise the terms "High GI" and "Simple Carbs" are synonymous.

The bottom line is that Complex Carbs are digested and absorbed by the body more slowly, which allows better hormonal regulation of insulin, glucagon, and cortisol. This in turn stabilizes blood sugar, preventing hypoglycemia caused by excess insulin and too little glucagon and cortisol, as well as preventing elevated blood glucose found in type 2 diabetes.

It should also be mentioned that eating any carb mixed with protein or fat delays the digestive process and thus effectively lowers the glycemic index of the meal.

Plants are the primary source of all carbohydrates. Fungi (mushrooms) are also a minor source. The more important question is, what are the glycemic index and glycemic load of different plant sources. There are published tables for this information.

In general, glycemic load should be balanced versus the protein content of each meal, and glycemic index should be minimized to reduce excess insulin response and reactive glycemia.

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  Fiber

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  [Wiki]
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  [Mayo]
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  [PubMed]