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CARBS Get a Bad Rap

CARBS Get a Bad Rap

Tuesday, May 5, 2015 Author: Susan Shapiro, PhD MS, MS, RDN, FAND, CAMS-I Categories: Nutrition
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Bread?! Pasta?! Potatoes?! You want me to eat what????  Such is the response I get from most people, regardless of the issue that brings them into my office, when I suggest adding grain carbohydrates to their diet.  I even hear this reaction from professionals!  Bread, potatoes, rice, beans, cereals, pasta, etc., which are also known as carbohydrates (CHO), have been given a bad rap since the 1972, when Richard Atkins published his book, Diet Revolution.

The truth is, if you follow the diet plan, you will lose weight, and you will lose it fast (men lose it faster)!  This is because the diet, in addition to being low in calories, also limits the TYPE and the amount of CHOs you can eat.  This combination produces a complex physiological response, which results in rapid and significant weight loss.  However, most of the weight lost is   muscle tissue, not fat.  And muscle tissue is the major determinant of how many calories we can eat on a daily basis.

Unfortunately, if you return to your usual diet (which most people do), you will gain weight (possibly all that you lost and then some). But the worst part is that most of what you gain back is fat.

The science, chemistry, physiology, etc. of dieting, and repeated dieting is VERY complex, and so much exciting information is still being discovered. There are many factors that are involved in weight loss and weight maintenance, especially the impact and importance of physical movement and exercise, but that is not the purpose of this article, and are also beyond the scope of this article.

The purpose of this article is to provide education about CHOs, what they are, why we need them, and how the body and mind, specifically the brain are impacted when we dont eat them or eat them in very limited quantities, and also when we skip meals or wait 6 hours to put some food into our mouths! Think of this article as a beginning.  Hopefully you will discuss this with a Registered Dietitian-Nutritionist (RDN) and find a way to incorporate them into your daily dietary intake. 

This article will also help you understand how your food intake impacts and plays a vital role in your mood, your behavior, as well as effectiveness of the medications you take for anxiety, depression, etc.

The first place to start is with a definition of a CHO, because if you know what it is, you will be able to make better food choices.

From a scientific/nutritional perspective a CHO is defined as a biological molecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms. There are two hydrogen atoms for each oxygen atom.  The empirical formula of a CHO looks like this: Cx(H2O)y (1).  This is why I use CHO to abbreviate carbohydrate. 

OK, so how does one use this information?  Well, lets try by describing this structure by using words. The x and the y are placers, in that their placement tells us that the number of atoms can vary.  It is this variation that creates different kinds of CHOs.

One way to understand this concept is to think about the cotton plant.  This plant has a basic structure, which can be modified and spun into a fiber that is then used to create many things: jeans, t-shirts, bed linens, etc. Sometimes other fibers are added to cotton to create jeans, t-shirts, linens, etc. and people will refer to these products as Cotton. This same concept can be applied to CHOs.

There are many types of CHOs.  The following are just a few of examples of words used in place of the word CHO, but they still mean CHO: simple, complex, mono/di and poly-saccharides (glucose, fructose, lactose), starch, sugar, glycogen, dietary fiber, processed CHO.

A simple CHO is defined by the quickness in which the body converts it to glucose (and energy). Examples of these are fruits, milk, yogurt, sugar (brown/white), honey, jams, syrups, hard and gummy candies, soft drinks, juice, etc.  I refer to these CHOs as sugar, milk or fruit CHOs. The reason for these labels is that milk/products and fruits also provide nutrients to the body, such as water, vitamins, minerals, fiber and other chemicals called phytonutrients that help promote health and prevent disease.

A complex CHO, which I refer to as GRAINS, are a form of CHO that have a longer digestion and absorption process before they are converted to glucose (and energy). Examples of these are breads, pastas, rices, cereals, quinoa, potatoes, corn, peas, legumes (i.e.: beans, lentils, soybeans.).  The foods listed here have often been referred to as starchy foods.  Many of these grains can be found as whole or refined grains. Refined grains have been enriched.  Enriched means certain B vitamins (thiamin, riboflavin, niacin, and folic acid) and iron are added back after processing. Fiber is not added back to enriched grains.

Processed CHO refers to foods that have been modified from their original form. When a food is cut, it technically is classified as a processed food. Processed foods also contain additives and substances intended to change the food in some way before it is sold.  Additives can change a foods taste, extend its shelf life, change the way it looks, and add vitamins, minerals, fatty acids and other supplements.  Even the package a food is in might be an additive, if the packaging leaches substances to the food they enclose (2).

So, given the above, the term processed CHO can be a bit confusing.  For this article, a processed food is one that is sold in a store and is prepackaged and one or more of the following words, in any combination, on the label.  These additives dont provide much nutritional value and should only be eaten on a limited basis: trans fat/ palm/palm kernel/ coconut oils/ Butylated HydroxyAnisole (BHA) /maltose/ maltodextrin/ corn syrup/ high fructose corn syrup/, sugar, /sodium nitrate & benzoate/MSG/ and aspartame/.

Another way to evaluate a processed CHO is to look at the total amount of CHO provided and see how much is from sugar. Sugar content can be found under the Total CHO listing on a food label. If the sugar content is more than 50%, it is considered a low grain, low nutritional product.  As for fat, if the  % of fat/serving is 30% or less, the product may have some nutritional value.  To know how much fat is in a product you divide the grams of fat by the grams of the serving size. For example, if a product has 4 grams of fat and the serving size is 28 grams then it has 14% fat (4/28 = 0.14). (3) (also the label below from this same source)

Fiber, specifically dietary fiber, refers to the part of fruits, vegetables and grains that humans cant digest. Many of these non-digestible substances are not fibrous at all. However despite not being fibrous we still call these parts fiber. There are two types of fiber. One is called soluble fiber and the other insoluble fiber. (4).

The following are some foods that have soluble fiber: oat bran, barley, nuts, seeds, beans, lentils, dried peas, oatmeal, oat cereal, apples, oranges, pears, strawberries, blueberries, cucumbers, celery, carrots and psyllium, a common fiber supplement. The following are some foods that are sources of insoluble fiber: whole wheat, whole grains, wheat bran, corn bran, seeds, nuts, barley, couscous, brown rice, bulgur, zucchini, celery, broccoli, cabbage, onions, tomatoes, carrots, cucumbers, green beans, dark leafy vegetables, raisins, grapes, fruit, and root vegetable skins.

Soluble fibers absorb water, and slow digestion because they help convert food into a soft/gelatinous substance.  This substance then becomes fermented by the bacteria in our gastrointestinal tract (GI).   The fermentation process is a very complex mechanism that enables our bodies to produce energy from glucose.  Insoluble fiber helps move food quickly through the GI, increases the size of the poop, and makes poop soft! (5)

Did you know that we have tons of bacteria in our gut?  In fact we have 10 times as much bacteria as cells! There is a growing body of research and belief that these bacteria can influence neural development, brain chemistry and a wide range of behavioral phenomena, including emotional behavior, pain perception and how the stress system responds. However, most of this research has been done in rodents (6).

So why is all of this important? This is significant because "glucose, aka CHO, is THE main source of fuel for the body, specifically, and most relevant for this article and for human viability, the brain.  When we eat CHOs, they are broken down, digested and absorbed by the body.  Most is stored in the liver and muscle tissue as glycogen. The remainder is stored in the blood as glucose, to be circulated to meet the continuous needs of the brain and the other organs in the body. 

When CHOs are not consumed on a regular basis, complex chemical reactions occur in the body so that glucose can be taken from the liver and sent to the blood for utilization. The amount of glycogen in the liver ranges from 8-10% of the weight of the liver. Muscle cells convert glycogen into glucose for utilization by the musculoskeletal system. Muscle tissue contains about 75% of total body glycogen. (7)

The body can also make glucose through a very complex process called gluconeogenesis. This glucose is made from non-CHO sources, such as pyruvate, lactate, some amino acids and glycerol (e.g. components in muscle tissue).  Fat is not converted to glucose (sad, isnt it?).  (7)

It is gluconeogenesis that maintains blood glucose concentrations, and provides a constant supply of glucose to the brain so it can function maximally, as well as all the other organs and various metabolic activities that the human body performs on a daily basis.  The brain requires a continuous supply of glucose because it has no capacity to store it. The brain consumes about 120 grams of glucose daily.  During sleep, the brain utilizes 60% of total body glucose needs. (7)

Have you ever noticed that sometimes in the afternoon, you might find yourself wanting something sweet, or feel a bit cranky, sleepy, and /or maybe a bit depressed?  This is because the amount of glucose in your blood, and your liver is low, so your body is trying to slow itself down to conserve glucose for your brain.  Remember your brain and all the tissues in your body have continuous energy needs. Energy needs are slightly elevated when we are awake, and they are still working even when we are sleeping!

After an intense workout, have you ever noticed that sometimes you find yourself hungrier than usual, sometimes, even a day after exercising as well? This happens because the amount of glucose in your blood and your body is low, and your body is telling you to feed it. 

The craving for sweets (cake, cookies, granola bars) or chips is because these types of foods (which some people refer to as CHOs) also have a high fat content. Fat delays the emptying time of the stomach, so the glucose that is in these foods is delivered slowly, and absorbed maximally, because the fat delays the digestion and absorption of nutrients. This is why a diabetic having an insulin reaction is given juice, or a sugar or glucose cube they need an immediate source of glucose or they will go into a coma and or possibly die.

I hope that many of you will consider adding minimally processed grains to your diet.  A guide to start is adding 150 calories at each meal and 100 at each snack. Your brain and your body will thank you. If you need more help, please contact an RDN. You can find one in your area at Eatright.org.

References:

1. Whitney, EN, Rolfes, SR. Understanding Nutrition. 8th edition. Chapter 4.

2. J Epidemiol Community Health doi:10.1136/jech-2013-202593

3. http://whatscookingamerica.net/Information/FoodLabels.htm

4. http://www.nlm.nih.gov/medlineplus/ency/article/002136.htm

5. Slavin JL. Position of the American Dietetic Association: health implications of dietary fiber. J Am Diet Assoc. 2008;108:1716-1731.

6. That gut feeling: With a sophisticated neural network transmitting messages from trillions of bacteria, the brain in your gut exerts a powerful influence over the one in your head, new research suggests. By Dr. Siri Carpenter  September 2012, Vol 43, No. 8 Print version: page 50

7. (Biochemistry 5th edition, Berg JM, Tymoczko JL, Stryer L. New York: W H Freeman; 2002). Berg JM, Tymoczko JL, Stryer L. Biochemistry. 5th edition. New York: W H Freeman; 2002. Section 30.2, Each Organ Has a Unique Metabolic Profile. Available from: http://www.ncbi.nlm.nih.gov/books/NBK22436/


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