Practical Nutrition/Macronutrients/Carbohydrates

Introduction.

Types of Carbohydrates

Carbohydrates that provide energy

Name	Description	Special Functions	Sources
Glucose	Simple sugar; primary energy source for cells.	Immediate energy; regulates blood sugar levels.	Fruits, honey, corn syrup, and starches
Sucrose	Disaccharide; composed of glucose and fructose.	Used as a sweetener and a preservative.	Table sugar, cane sugar, beet sugar, maple syrup, and molasses
Ribose	A simple sugar that is part of the backbone of RNA and DNA.	Essential for nucleotide synthesis	RNA, DNA, ATP, NADH, FADH2, and some fruits and vegetables
Amylose	Component of starch; linear glucose chains.	Slower digestion; gradual energy release.	Starchy foods such as potatoes, rice, wheat, and corn
Amylopectin	A branched polymer of glucose units that is a component of starch.	Quick energy release.	Found in starchy foods such as potatoes, rice, wheat, and corn
Maltose	Disaccharide; composed of two glucose units.	Used in brewing and food processing.	Malt, beer, bread, cereals, and some fruits and vegetables
Galactose	A simple sugar that is part of the disaccharide lactose.	Essential for lactose synthesis.	Milk, dairy products, and some fruits and vegetables
Fructose	Monosaccharide; sweetest natural sugar; part of the disaccharides sucrose and lactose.		Fruits, honey, agave nectar, and high-fructose corn syrup
Lactose	A disaccharide composed of glucose and galactose.	Primary sugar in milk; essential for infants.	Milk, dairy products, and some processed food

Complex vs Simple Carbs

Simple carbs are short chains of sugar molecules that are easy to digest and provide quick energy. Complex carbs are longer chains of sugar molecules that take longer to digest and provide more stable energy. Complex carbohydrates are digested slower and release glucose into the bloodstream at a more gradual rate. On the other hand, simple carbohydrates are digested rapidly and spike blood sugar faster and higher than complex carbs.

Carbohydrate Types

Carb Type	Simple or Complex	Examples
Monosaccharides	Simple	Glucose, fructose, galactose
Disaccharides	Simple	Sucrose, lactose, maltose
Oligosaccharides	Complex	Raffinose, stachyose, fructooligosaccharides
Polysaccharides	Complex	Starch, glycogen, cellulose

Sources

Figure 1.1. Image depicting wheat products

Figure 1.2. More examples of carbs, less healthy options

Carbohydrates are the most abundant macronutrient in our food supply. They are found in these, among other foods:

• Rice, pasta, bread (wheat products; see fig 1.1)
• Sweet potatoes
• Cereal and quinoa
• Bananas and apples (and other the majority of other fruits)
• Beans and lentils (legumes)
• Doughnuts, potato chips, soft pretzels, candy, french fries, etc (most processed or sweet food; see fig 1.2)

Practical Tips

• Choose whole grains over refined grains. Whole grains contain more fiber and nutrients than refined grains. Examples of whole grains include brown rice, quinoa, oats, and whole-wheat bread and pasta.
• Eat plenty of fruits and vegetables. Fruits and vegetables are low in calories and high in nutrients, including fiber, vitamins, and minerals.
• Limit your intake of processed foods and sugary drinks. Processed foods and sugary drinks are high in simple carbohydrates and added sugars, which can contribute to weight gain and other health problems.

Whole grains

Don't Be Tricked By Packaging

Navigating Tricky Wording - Identifying Whole Grains

Packaging Terms	Whole Grain?	% of wheat in the item that is required to be whole grain
"100% Whole Wheat" or "100% Whole Grain"	Yes, best option.	100%
"Whole Wheat" or "Whole Grain"	Yes	>51%
"Organic Flour"	Maybe
"Stone Ground"	Maybe
"Brown Rice"	Yes	100%
"Bran"	No
"Wheat Germ"	No
"Wheat berries"	Yes	>51%
"Enriched Wheat Flour"	No
"Multi Grain"	Maybe
"Wheat"	Maybe

Comparison of Carbs and Fats

Carbohydrates and fats are both used in the body for energy, but they differ in the amount and speed of energy they supply, as well as the way they are stored and utilized. Here is a comparison of how they are used in the body:

• Carbohydrates are the quickest source of energy, as they can be broken down and absorbed by the body quickly. They provide 4 calories per gram*. The body uses carbohydrates to fuel the brain and nervous system, as well as to maintain blood sugar levels. Excess carbohydrates are stored as glycogen in the liver and muscles, which can be quickly converted back to glucose when needed. However, the storage capacity of glycogen is limited, and any excess carbohydrates beyond that are converted to fat and stored in adipose tissue. Adipose tissue will be discussed later.
• Fats are a slower source of energy (more apt for long-term storage than carbs), as they take longer to digest and absorb by the body. They provide 9 calories per gram*. The body uses fats for cell membrane structure, hormone production, and absorption of fat-soluble vitamins. Fats also serve as a backup source of energy when carbohydrates are not available. The body can store abundant amounts of fat in adipose tissue, which can be mobilized and oxidized when needed.
• Carbohydrates and fats can be used for different types of physical activity, depending on the intensity and duration of the exercise. Carbohydrates are mainly used for high-intensity and short-duration activities, such as sprinting or weight lifting, as they can provide quick bursts of energy. Fats are mainly used for low-intensity and long-duration activities, such as walking or jogging, as they can provide sustained energy.

*See this section on macronutrients and calories for review if needed.

Fiber

Listen to this lecture on fiber:

An in-class lecture on the role of fiber in the body.

Lecture summary:

• Fiber only comes from plants
  • You can't get fiber from meat, or any other animal sources.
• Fiber is a carbohydrate, there is no fiber in fats whether animal or plant-based.
• 97% of Americans don't get enough fiber.
• The process of juicing a fruit removes fiber.
• If fiber is contained in the skin of fruit (like apples), when you peel the skin off before eating it, you are removing a lot of its fiber.
  • Large apple with skin: 5.4g of fiber.
  • Large apple without skin: 2.8g of fiber.

    

    Think twice before peeling! You're missing out on about half the fiber that the apple offers in its skin.

• Benefits of fiber: satiety (feeling full), feeds good bacteria in our gut microbiome, helps eliminate waste (poop), reduces risk of obesity and type II diabetes.
  • Without gut bacteria, we can't digest fiber on our own.
    • The good bacteria in our gut digests and thrives on fiber. The good bacteria in our gut helps us maintain a healthy gut microbiome (see next bullet)
• Side note: the gut microbiome plays a crucial role in preserving human health through nutrient provisioning, vitamin K synthesis, cellulose digestion facilitation, studies have also suggested it supports the promotion of angiogenesis (forming of new blood vessels from existing ones) and enteric nerve function.

  

  Not all bacteria is evil!

• Fiber contributes 0 calories.
  • Fiber adds "bulk" to food.
  • Stretch receptors in the stomach send a message of fullness to the brain.
• Our bodies absorb nutrients when they come in physical contact with our intestinal walls.
  • Fiber can help clean out the waste that lines intestinal walls.
    • Having excess waste on the intestinal walls can negatively affect nutrient absorption and cause other problems.