REGENESIS OF ERIE: 2020

Sunday, March 15, 2020

Macro Nutrients: Carbohydrates II

Greetings!

Last week we introduced the bare basics of the carbohydrate world. We saw the basic molecular structure, the difference between the different saccharides, and learned that different carb categories come from different food sources. Today, we will look take a closer look into what carbohydrates actually do in the body and the difference between a simple and complex carb.

Carbohydrates have multiple functions, but we can look at them in four categories: (1)

1. Used directly as energy by cells
2. Stored and used as energy for later use
3. Conversion into fat
4. Prevention of tissue breakdown

Carbohydrates: The body's principal energy source

Let's start with the most common answer, energy usage. Carbohydrates are always being used as energy in our bodies, whether it's exercising or reading this blog, they are in some shape or form in the process of converting or assisting in energy production. The Central Nervous System demands a steady supply of carbohydrates as well as the brain and red blood cells (1), which almost solely uses glucose as fuel (except when extreme conditions demand otherwise). Once a carbohydrate enters your body, at some point in it's lifespan, it will be used as energy or at least aid in this process. If it is not used for immediate energy it will be stored in two forms for future use.

As we discovered in an earlier post (ATP) the body uses ATP to provide the essential energy to function. We also talked about those wonderful processes that convert proteins, fats and carbohydrates into said ATP. Glycolosis converts glucose (remember that giant process?) to this ATP, but one thing I never discussed is how the glucose got there in the first place. You see, it matters not if you eat a complex carbohydrate or a simple one, they all must be broken down into simple sugars in order to begin their journey into the the conversion of energy. We will discuss how this and other digestive properties work down the road as we put all the pieces together, but for now we must understand that once we ingest a carbohydrate, it needs to be broken down into it's most basic form in order to convert into ATP.

Yeah, it's pretty complicated.

The first form of energy is an immediate source in the more commonly known, blood glucose or blood sugar. The carbohydrates we ingest will be broken down and circulated in our bloodstream, which are then available for instant usage. The other from is stored glucose called glycogen. This is stored in the muscles and in the liver, until it is called upon once the instant source of blood glucose is used up. The process of Glycogenolysis, converts this glycogen into glucose and is then ready to head through the energy conversion process. This process is most often used in intense exercises such as; weight lifting, sports and manual labor.

Carbohydrates are used every moment of the day, but as I said earlier, they are heavily used during moderate to intense physical activity. This happens through an anaerobic process, meaning oxygen is not needed for energy conversion. Generally, any challenging activity lasting from 30 to 90 seconds, weight lifting being the best example, relies on carbohydrates for it's primary energy source. This is where the stored glucose comes into play because as we continue to exercise we need more energy from glucose, thus the stored glycogen in the muscle and liver release and allow us to continue to exercise, but of course that won't last forever, which is why you will see a decrease in performance after each hour of exercise (2). This is the exact reason why athletes, marathoners and weight lifters perform some sort of "carb load" at some point before their event so they can have a steady supply of carbohydrates for energy. Even though longer lasting activity relies on lipids as it's primary fuel source, we have a saying in the physiology world "fat burns in the flame of carbohydrate" meaning, carbohydrates are needed even if they are not the primary fuel source.

A steady supply of carbohydrates allows the energy conversions to occur at a normal pace, but what if there were no carbohydrates to convert? Our bodies will find a way to make energy as long as there is some form of raw material to do so. Keeping a healthy amount of carbohydrates in our bodies is far more important than just for exercising, they help prevent catobolism and ketosis (leading to ketoacidosis) (1). In extreme cases, starvation for instance, the body will break down muscle tissue in order to convert it into amino acids, which can then be put through one of the energy cycles. The problem is when our bodies enter this catabolic state, it literally eats itself away (hence the withering of a person suffering from starvation) which can have many negative long term health effects. When our bodies use stored fat as an energy source for it's primary fuel, ketone bodies accumulate and can also have negative affects, from ketoacidosis or having a higher blood pH (that's bad). (2)

Finally, when the liver glycogen stores are full, the excess glycogen will be converted into fatty acids, which will then hitch a ride in the bloodstream and be dropped off at the various Adipose tissue in the body. Of course, if this process is utilized too often, total body fat increases and obesity can occur. This very concept is why carbohydrates have become the enemy in the diet world. The hundreds of carb-free diets and carb restricted rules have taken over, but only because many do not know the basic functions of carbohydrates. The major problem is not so much the carbohydrates, but rather how easily they are obtained and how much you can ingest before you realize it. Ever take a look at the total carbohydrates on a big bagel or muffin? They can have up to 40-50g of carbs. According to the 2010 US dietary guidelines, Americans should be getting 45-60% of their total calories from carbohydrates. At 200 calories (50g x4 kcal) that would be about 10% of your daily caloric intake right there, so imagine if you had a glass a juice and other breakfast foods to go with that. We will discuss calories and percentages of, and examples in later blogs, but just remember it is very easy to consume excess carbohydrates without ever knowing it.

Now we have a general understanding of what some typical carbohydrates are in the everyday world and their basic functions in the body. In the next blog we will differentiate between simple and complex carbs, how they are broken down in the body and the effects they have on our various physiological functions (insulin and blood sugar). The carbohydrate is an essential component of our everyday lives and I think after the next installment we will be able to fully appreciate them, now that we understand their roles and the differences that separate them.

Thanks for reading!

“Life is largely a matter of expectation. ” - Homer

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*I am not a doctor or a licensed physician. I am in no way diagnosing anything and recommend that you speak to your physician before making any medical/supplemental/nutritional decisions.

*I am not a registered nutritionist or dietitian. The information presented is for education purposes only.

1. MxArdle,W. Katch, F. Katch, V. Sports and Exercise Nutrition 4th edition (3-19 & 147-161) NY: Lippincott Williams & Wilkins

2. Powers,S. Howley, E. (2007) Exercise Physiology Theory and Application to Fitness and Performance 6th edition (478-482) NY: McGraw Hill

Wednesday, February 26, 2020

Macro Nutrients: Carbohydrates

Hello! After some experimenting with the new controls of the new site, I have finally (I think) figured out the new settings and controls of the blog page. Thank you for being so patient during the long lay over and construction of the new site! That being said, in the spirit of getting the grasp on the basic handles of things, I thought it might be wise to take us back to the ground level and get a better understanding of our basic macronutrients: Carbohydrates, Proteins and Lipids (Fat).

Whether simple or complex, carbohydrates come in many forms and structures.

Today we will focus on the most demonized of the three over the past decade; Carbohydrates. All living cells contain carbohydrates, which we get primarily from plant based foods. Carbohydrates have been deemed “bad” among many health buffs, because of the fact that excess consumption of carbohydrates can indeed be converted into fat and of course consuming too many simple sugars can drastically increase the risk of diseases such as type-II diabetes. Perhaps if we understood what a carbohydrate actually is, then understand how they work and their role in the body, it may help us understand how to and how much to consume, which is my goal for the oncoming post as we tie them all together.

Photosynthesis: By synthesizing carbon dioxide and water, carbohydrates are formed.

The majority of carbohydrates come from plant sources and as the name would suggest, contains carbon and water. Combine carbon, oxygen and hydrogen and you would have an actual carbohydrate, which is created from that old process known as photosynthesis. As the sun provides energy, water, carbon dioxide and chlorophyll interact to form glucose, the most typical sugar. Roughly 75% of a plant's dried contents are carbohydrate based. (1) From this point, carbohydrates can be categorized into three major categories: Monosaccharides, Disaccharides, and Polysaccharides.

A molecular structure of glucose. We can tell just from the hexose structure that this is a monosaccharide

Clasic mono and disaccharides in their better known forms.

Monosaccharides: The basic unit of carbohydrates also known as simple sugars. There are over 200 monosaccharides in nature (2), but we will focus on the hexose variety (6 carbon atoms in their molecular structure); Glucose, Fructose and Galactose. Glucose (Blood sugar) is found naturally in foods and is the most typical sugar. Fructose, the sweetest of the simple sugars is found mainly is fruits and honey. Galactose does not occur freely in nature, but forms milk sugars in lactating mammals. (1)

Disaccharides: When two monosaccharides combine we have ourselves a disaccharide. These are also known as simple sugars. Disaccharides contain glucose and compose of three types: Sucrose, Lactose and Maltose.

Sucrose: Equal parts glucose and fructose make up sucrose. Table sugar is the most common example, but many foods that contain carbohydrates also contain sucrose.

Lactose: Known as milk sugars, lactose is only found naturally in milk and is composed of glucose and galactose. If you are lactose intolerant than this simple sugar is not your friend as your body lacks the amount of enzymes responsible for breakdown of lactose.

Maltose: Made up from two glucose molecules most commonly found in beer and cereal. Maltose accounts for a very small portion of our carbohydrate intake.

Starches and fiber come from many sources, but not all types starch and fiber are alike.

Polysaccharides: Can be formed from as little as ten or comprised of thousands of monosaccharides, this group of carbohydrates are divided into plant and animal varieties. We will focus on plant based polysaccharides, as animal (glycogen) is more interesting if we are discussing physiology. When talking about plant polysaccharides we know them traditionally as starch and fiber. Starch is the most familiar plant polysaccharide and is the storage form of carbohydrates in plants.(2)

Starch is plentiful in seeds, grains (pastas, breads, cereals) and potatoes among others. Starch exists in two forms: amylose and amylopectin. Amylose is constructed in a long chain of glucose molecules which looks like the picture below and break down slower in the body compared to the amylopectin structure, which offers a greater surface area, thus allow for faster breakdown in the body. We will discuss the difference between the breakdown, absorption and usage of each of these starches in the coming posts. Fiber, the other plant polysaccharide, is another carbohydrate that contains cellulose, the most abundant organic molecule on Earth. Found only in plants, fiber is classified into two groups; soluble and insoluble. Again, we will discuss their role more in depth at a later date, but for today we will focus on introducing them.

Amylose, a long straight chain of glucose molecules, breakdown slower in in the body. Whereas, amylopectin has a higher surface area and allows for more rapid breakdown.

Think of starches and their surface area like this. Amylopectin fans out allowing digestive enzymes a better shot of grabbing hold, thus breaking down faster in the body.

Soluble Fiber: Able to dissolve in water, insoluble fiber is found in fruits, oats, seeds, nuts and beans. Once it meets up with water it forms into a viscous gel, which can help slow digestion and appears to help regulate blood sugar levels, which research has shown has the ability to lower cholesterol (LDLs) (1)

Insoluble Fiber: Unable to dissolve in water, these types of fiber help speed food throughout the digestive tract, thus are often recommended for those with constipation due to this laxative effect. Insoluble fiber can be found in vegetables, grains, roots and leaves. (1)

Carbohydrates, both simple and complex can come from many sources. Some are obvious, but others not so much.

There we have it, the cast to our ongoing series of blogs to come in the carbohydrate department. There plenty of other interesting details about different saccharides, glycogen, pectin and of course the chemical components of them all, but for the sake of time we will stick to the members of the carb family most often seen and heard everyday. Our journey has just begun so stayed tuned for the next installment and discover what carbohydrates'' role are in the body and why we shouldn't fear them as much as we have been led to believe. BTW, Below is a structure of glycogen molecule. Take a look on how complex these guys can get! Thanks for reading!

“Courage is not having the strength to go on; it is going on when you don’t have the strength.” -Theodore Roosevelt