FN 225: Nutrition
Tamberly Powell, M.S., R.D.
Health Professions Division
Lane Community College
LECTURE 4B: Carbohydrates
EXAM during Week 5 (over both parts of chapter 4), so study:
This lecture will cover the following topics:
Your LECTURE OUTLINE describes the definitions we'll use of foods that are WHOLE, PARTITIONED or REFINED. Sometimes other definitions are used, but these are the ones that we'll use.
Juice is an example of a partitioned
food. When making juice from something like an
orange, the main thing that is removed is the fibrous part of the orange.
From these definitions, see if you can pencil in what you think the listed foods in the lecture outline would be, WHOLE, PARTITIONED or REFINED. Feel free to discuss this in the forums.
Consuming lots of refined foods can change carbohydrate intake in two important ways. It can increase your sugar intake and decrease your fiber intake.
When trying to determine if a food is high in sugar, you can look at the food label for grams of sugar. Keep in mind the sugar on a label does not distinguish between naturally occurring and added sugars, as of yet.
Directly below are the Nutrition Facts for a 12-ounce can of Coke. Here the Serving Size for the Nutrition Facts is 12 ounces.
Fill in these above values in the blanks of that part of your Lecture Outline.
That 12-ounce can would have almost 10 teaspoons of sugar (39 grams of sugar divided by 4 grams per teaspoon).
Directly below are the Nutrition Facts for a 20-ounce plastic bottle of Mountain Dew. Here the Serving Size for the Nutrition Facts is 8 ounces. If you were to drink the whole bottle you would need to multiply the 31g of sugar (and calories) by 2.5 (the number of servings).
If you drank this whole bottle of of Mountain Dew, you would be getting almost 20 teaspoons of sugar.
(31 grams of sugar divided be 4 = almost 8 teaspoons of sugar per 8 ounces. 8 teaspoons of sugar multiplied by 2.5 servings per bottle = almost 20 teaspoons of sugar for the entire 20-ounce bottle.)
This 64 oz. soda has 186 grams of sugar, and about 46
teaspoons of sugar (186g divided by 4g/teaspoon).
Above are the Nutrition Facts for an 8-ounce serving of Blueberry Yogurt. The 39 grams of sugar shown on the Nutrition Facts are a combination of both added and naturally occurring sugars. I know this from looking at the ingredient list. Naturally occurring sugar is coming from the lactose in the milk, fructose and sucrose in the blueberries and added sugar is coming from the sucrose in table sugar.
The only way to know how much sugar is added and how much sugar is natural is to do a little detective work since the label does not distinguish between the two.
Above are the Nutrition Facts for an 8-ounce serving of Plain Yogurt. There is no added sugar (because there are no added sugars in the ingredient list) so the 17 grams of sugar shown on the Nutrition Facts is coming from lactose in the milk.
So you might be thinking well how much added sugar do I need in the first place? The new 2015 dietary guidelines recommends less than 10% of total Calories coming from added sugars because of its link to obesity and chronic disease. This would mean that someone eating a 2,000 Calorie diet would want to limit their added sugar intake to about 12 teaspoons per day.
Americans consume 22 to 30 teaspoons of added sugar daily, half of which come from soda, juices and other sugary drinks. The dietary guidelines are recommending for people to drink more water and less sugary drinks.
It is important to limit the added sugar in our diets because high sugar intake causes tooth decay, may lead to unhealthful levels of blood lipids, and is also associated with diabetes and obesity.
I don't encourage people to keep track of their added sugar intake (it would be almost impossible to do since labels don't specify the type of sugar in processed foods), but I do encourage people to focus on WHOLE foods that are minimally processed and to consume added sugars, and foods with added sugars in moderation.
If you want to read more about sugar, the following article has a lot of great information about the complicated science of sugar. "Sugar explained. Sugar is the dietary villain of our day. But the science is complicated."
D. Enrichment. Enriched vs. Whole Wheat Bread
|The lecture outline tells you that if a food label uses the term enriched,
it means that 5 specific nutrients are required to be added to white or wheat
(refined) flour and its products as well as to white rice. Those 5
nutrients are added at levels about what they would have been before the
flour or rice was refined.
The Enrichment Act requires that these 5 nutrients be added to all refined grain products before they are sold, so you only see in stores white flour that says "enriched".
The brown part of the above bar chart represents the thiamin content of a slice of WHOLE wheat bread.
The green part represents the thiamin content of a slice of white bread. Notice they are about equal because the white flour used in the white bread is required to be enriched with thiamin, riboflavin, niacin, folic acid and iron.
Notice above that a slice of WHOLE wheat bread has significantly more vitamin B6 compared to white bread because white bread is not required to be enriched with vitamin B6.
Below is an illustration that shows other nutrients "enriched" flour is low in compared to Whole Wheat bread.
Sometimes a bread looks like it would be whole grain, but actually just a small part of the flour is whole.
The first ingredient of this Cracked Wheat bread is wheat flour (see above ingredient list) but that wheat flour is white. If a bread is called "Wheat Bread", its first ingredient is probably white flour or enriched wheat flour. (White flour = enriched wheat flour). Wheat flour is a generic term. If it is enriched it is white flour, if it is whole, it will say whole wheat flour.
It says the wheat flour is unbleached. Bleached and unbleached flour have almost the same nutrients. Consider them equal and consider them both white flour.
A clue that it doesn't have much whole wheat is the fiber content. If it was a whole wheat bread it would most likely be a good source of fiber, > 10% DV.
Keep in mind that when a bread is called "Wheat Bread" it usually means that the first ingredient will be enriched wheat flour, which is a white refined flour.
The fiber content of this "Whole Grain White" is misleading, I think, because the first value is for TWO slices.
The first ingredient is
"ENRICHED BLEACHED FLOUR"The remaining ingredients are:
(white flour which it calls wheat flour, then it lists barley flour, then the B-vitamins it's enriched with including niacin, thiamin, riboflavin and folic acid and the mineral it's enriched with, iron).
(whole wheat flour, brown rice flour [rice flour, rice bran)WHEAT GLUTEN
CONTAINS 2% OR LESS OF EACH OF THE FOLLOWING:
BUTTER (CREAM, SALT)
MONO- AND DIGLYCERIDES
ETHOXYLATED MONO- AND DIGLYCERIDES
SODIUM STEAROL LACTYLATE
So this bread is not a whole wheat bread.
These days, many breads that are made entirely with WHOLE grain flour use 100% on the label. But to truly know if a bread is WHOLE grain you need to look at the nutrition facts. 1. Make sure it lists a whole grain (like whole wheat) as the first ingredient, AND 2. make sure it is a good source of fiber (DV >10% for fiber).
Also, products that are whole grain might have a whole grain stamp (shown below) on the packaging.
For more information on the above stamp, check
Whole Grain Council website.
For more information on how to determine if grains are truly whole grain view this short powerpoint.
|Now go back to the part of the lecture
outline where you're asked to label whether
you think the
listed foods are WHOLE,
PARTITIONED or REFINED.
What would you say about "wheat flour"?
There are at least two reasons why processed foods are often cheaper than whole foods.
One is that processed foods can be stored longer before they need to be purchased or used. The germ in whole wheat flour has beneficial fats in it that can go rancid if not sold and used right away. Fresh vegetables and fruits have enzymes in them that cause the food to decompose. While the processed foods can be stored longer, the processing cause them to lose MANY beneficial nutrients.
The above photo of a 1980 Sno Ball cupcake was taken in 2006. The cupcake was just thrown away when we moved offices in 2010.
A second reason why processed foods are often cheaper than whole foods is that processing can divide a food (like corn) into many parts that then can be sold individually. It's not the farmer who sees this profit.
In his 2006 book The Omnivore's Dilemma: A Natural History of Four Meals, Michael Pollan writes, “Every farmer I've ever met eventually gets around to telling the story about the food industry executive who declared 'There's money to be made in food, unless you're trying to grow it.'” (page 95 of The Omnivore's Dilemma)
|Refining is used to obtain other additives used in food processing besides sweeteners.
Three additives make up the "fiber blend" of the pasta on the right. All 3 of these additives (inulin*, xanthum gum and pectin) are non-digestible carbohydrates made by plants, but in the case of this pasta, it takes a factory to refine them from the plants, the way it takes a factory to refine table sugar from beets or corn.
When I did a web search to find out where inulin is manufactured, I found 4 regions listed. The majority were in mainland China, some were in the U.S and others were in Australia and Vietnam.
Persons choosing to eat foods with inulin should watch for signs of gas and bloating, which occurs in some people (this was discussed in lecture 4A). Note that the pasta also has the additive wheat gluten. Gluten is a protein naturally found in wheat, but gluten intolerance is becoming increasingly common, including among people with diabetes.
* "Inulin" is no relation to "insulin". It gets its name from inula, a large genus of about 90 species of flowering plants in the family Asteraceae, native to Europe, Asia and Africa.
The following website shows you an alphabetical listing of additives (including the sorbitol you see in this pasta) with an evaluation of their safety: CSPI's Guide to Food Additives (Center for Science in the Public Interest).
What it says about sorbitol is:
"Some diabetics use sorbitol-sweetened foods because it is absorbed slowly and does not cause blood sugar to increase rapidly. Moderate amounts of sorbitol are safe, but large amounts may have a strong laxative effect and even cause diarrhea."
Digestion and Absorption of Carbohydrates
In the beginning of lecture outline 4-2, when we discussed the different types of carbohydrates we discussed which carbohydrates needed to be enzymatically digested. The primary goal of carbohydrate digestion is to break polysaccharides and disaccharides into monosaccharides which can be absorbed. Below is another review of this.
1. After eating, nothing needs to happen in the digestive tract to the monosaccharides in a food like grapes because they are already small enough and they are absorbed as is.
2. Disaccharides in that grape or in a food like milk are broken down (enzymatically digested) in the digestive tract to monosaccharides (glucose, galactose, and fructose).
3. Starch in food would be broken down (enzymatically digested) in the digestive tract to glucose molecules.
4. Fiber in food would NOT be broken down in the digestive tract because we don't have the enzymes to do that.
B. Carbohydrate in Foods
Below you will get some practice in identifying if a food has carbohydrate(s) that need to be enzymatically digested. But first let us review where we find carbohydrates in foods.
Fruits- Fruits are sweet so we know they must contain sugar. Fruits contain sucrose, glucose, and fructose. If we are eating whole fruit, it will also contain fiber, since fiber is found in all whole plant foods.
Vegetables- Some vegetables are sweet and also contain sugar. Similar to fruits, some vegetables (like carrots and green beans) contain small amounts of sucrose, glucose, and fructose. Again, if we are eating whole vegetables, they will also contain fiber. Starchy vegetables (corn, peas, potatoes) will also contain starch.
Dairy- This is the one animal food that contains carbohydrate. Milk, cheese, and yogurt will contain lactose. If dairy (like yogurt) is sweetened (sugar is added) it might contain sucrose (white cane sugar) or fructose and glucose (honey and/or HFCS) depending on what type of sugar is added.
Grains- Grains will naturally contain starch and fiber. If they are sprouted grains they will also contain maltose. If grains are sweetened (sugar is added) they might contain sucrose (white cane sugar) or fructose and glucose (honey and/or HFCS) depending on what type of sugar is added.
Protein- Meats will not contain carbohydrate, but other foods that fall into the protein group (beans and nuts) will contain starch and fiber. Remember these are seeds.
Fats- Concentrated fats like butter and oil do not contain carbohydrate.
Looking at all the foods that contain carbohydrates, you might be able to guess why eliminating carbohydrates from the diet can lead to weight loss. It drastically reduces the variety or choices one has, leaving you with low carbohydrate veggies, and meats. People usually consume less calories with this way of eating. However, for most people this is not a sustainable or enjoyable way of eating. Nutritionally it is also not a balanced diet.
Okay with the information above, you should now be able
to determine which foods listed below have
carbohydrate(s) that need to be enzymatically digested.
|C. Locations in the body
where bacterial digestion of carbohydrates can be a problem.
two locations in the body where bacterial
digestion of carbohydrates can be a problem. One is the mouth and there
other is the colon
|What is left on the teeth
as a result of this anaerobic breakdown is
pyruvic acid. This pyruvic acid destroys the
enamel of teeth with the result being cavities.
A few of the ways to decrease your risk of cavities are:
The second location in the body where bacterial digestion of carbohydrates can be a problem is in the colon.
Humans, like most other mammals from buffalos to yaks, produce lactose for the milk to nurse their young. It gives their milk an appealing sweet, but not overly sweet, taste. (It has about half the concentration of sugar as the average soft drink.)
This photo of a nursing elephant, as well as the following photo, was taken by Courtney Fitzpatrick, who grew up in Eugene. She is a doctoral student at Duke University in North Carolina and her research takes her to Kenya.
This is at the David Sheldrick Wildlife trust in Nairobi, an organization that cares for orphaned elephants and then eventually reintroduces them to a specific state park in Kenya. Apparently they have pretty high success rates, although it takes a huge amount of human hours to care for them!
The enzyme lactase, made by a baby, breaks down lactose into two simpler forms of sugar (glucose and galactose), which are then absorbed into the bloodstream and provide glucose to fuel a baby's rapid growth. While fat in the milk can provide energy for the baby's muscles, as we've discussed, glucose is the only significant fuel the human brain and nervous system usually uses.
Once a baby stops nursing, most slowly lose the ability to make lactase. While this condition is called lactose intolerance, it's the normal condition for most of the world. About 75% of the world's adults are lactase-deficient, including most Asians, Southeast Asians, Africans, Middle Easterners and Native Americans.
Northern Europeans, among whom lactose intolerance is uncommon, have at least a 10,000-year history of dairying and milk consumption which is different from most of the rest of the world. A hypothesis is that at some unknown point in time, a mutation or adaptation occurred that enabled Northern Europeans to produce the enzyme lactase and digest milk as adults. Through natural selection, the frequency of the genetic trait for lactose tolerance increased in dairying societies because individuals with this genetic trait had the advantage of being better nourished. Not only did the milk provide protein, also their calcium absorption was increased by the lactose and the small amount of vitamin D in the milk. In societies living closer to the equator such as in Africa, the sun's ultraviolet light helped them manufacture vitamin D. In Northern Europe, cloud cover limits sunlight for much of the year.
Human intestines are full of bacteria that are not lactase-deficient. The bacteria break down lactose because they want the fuel it can provide. This intestinal fermentation produces hydrogen and other gases and molecules that attract water. This can produce symptoms like nausea, gas, bloating, cramps and diarrhea.
For a person with lactose intolerance, symptoms begin about 30 minutes to 2 hours after eating or drinking foods containing lactose. One term, a student told me that "lactose intolerance is one of those sliding scale things" and she was exactly right. The severity of symptoms depends on many factors, including the amount of lactase a person makes and the kinds of bacteria they host. For these reason, not all people deficient in lactase have the symptoms commonly associated with lactose intolerance.
We definitely do not need to drink milk as adults but what we DO need is calcium and some people find it difficult to get enough calcium without drinking milk.
Getting enough calcium if lactose intolerant:
A. What happens to make blood sugar rise.
After eating foods with carbohydrate, these carbohydrates are digested
by enzymes down to monosaccharides and these monosaccharides
are absorbed into the blood. Then the fructose &
galactose are changed to glucose in the liver.
1. When your blood sugar falls, you receive messages from your brain & nervous system to eat.
2. If you don't eat, your body's first way of
getting glucose to raise your blood
sugar is to break apart the glycogen in the
liver. (Glycogen in the muscles can only be used
in the muscles so it doesn't get into the
blood to travel to other parts of the body).
From the above explanation, you should now be able to answer these questions:
What do insulin & glucagon have in common?
How are insulin & glucagon different?
If you're not sure, post a question in the forum.
3. If you have already used up your liver's glycogen, the next way your body has of getting glucose is to rearrange the protein in muscles into glucose.
Which of the components of muscles are surprising to you?
So when your blood sugar falls & liver glycogen is gone, protein in muscles can be used to raise your blood sugar.
Now you should be able to list the 3 ways your body can raise your blood sugar.
1. Eat 2. Breakdown liver glycogen 3. Rearrange protein into glucose
Notice there is no mention about fat above. If you were in a situation where you would need to rearrange protein into glucose (starvation or a very low calorie diet) you would be using fat as a fuel, you would just NOT be using significant amounts to make glucose for the brain.
I say significant, because there is a small part of the fat molecule (glycerol) that can be converted to glucose. However, the major part of fats, fatty acids, can not be rearranged to make glucose. This will make more sense when we discuss triglycerides next week.
Here is a screen cast that explains this concept a bit more.
Here is a link to the above video: https://youtu.be/9TpjotC1m30
In the screencast I mention that both amino acids and glycerol can be used to synthesize pyruvic acid and therefore glucose. That is because these are 3- carbon compounds which can be converted to pyruvic acid. Notice the two-way arrow between pyruvic acid and glucose. Pyruvic acid can be used as a building block to synthesize glucose, therefore glycerol and amino acids that are broken down in 3-carbon units can also synthesize glucose.
Fatty acids, and amino acids broken down in 2- carbon units that enter at the point of Acetyl CoA do NOT synthesize glucose. Notice the one way arrow between pyruvic acid and Acetyle CoA. This is the point of no return.
C. Excesses of Glucose
Notice the double way
arrow above between fatty acids and Acetyl CoA. Fatty acids can be
broken down to make Acetyl CoA which then can go through the Krebs Cycle
to make ATP for cells to fuel their work. BUT Acetyl CoA can also
be used to synthesize fatty acids. So if there if too much
glucose, or amino acids, they can be converted to fatty acids.
|D. Deficiencies of Glucose
cells are deficient in glucose, it causes a buildup of ketones
in the blood, something that is called ketosis.
The Krebs Cycle is the aerobic part of Cellular Respiration, meaning that part requires oxygen. Can you see that oxygen is added to the Krebs Cycle, but not to Glycolysis? And can you see that the Krebs Cycle needs glucose to get started?
When fat is used for energy, the 2-carbon fatty acid fragments go though the Krebs Cycle. But if glucose is not in the cells, the Krebs Cycle is limited and the 2-carbon fatty acid fragments combine to make 4-carbon ketones, shown below:
When these ketones build up in the blood, that is called ketosis. One situation that can lead to less glucose being in cells and therefore ketosis is starvation. Another is uncontrolled diabetes because there is not enough insulin to help glucose enter cells or cells do not respond to the insulin. You have also probably heard of people going into ketosis by eating a high protein, low-carbohydrate diet (< 50 grams per day).
Symptoms of ketosis include decreased appetite as well as increased thirst & urination. Ketones are excreted from the body by several routes, including the mouth and the urine. Since they leave a disagreeable taste in your mouth, ketones can decrease appetite.
In order for the kidneys to work effectively, they like substances that come their way (be they salts or sugars or ketones) to be dissolved in plenty of water. So the kidneys signal you to drink more water. This extra water leads to increased urination.
Short-term ketosis itself might not be dangerous, except if diabetic or pregnant. But if your body is in ketosis, what does this also mean is happening in the body?
(Hint- If you're in ketosis, it means your cells aren't getting enough glucose. So how will your body make sure your brain gets some glucose?)
Rearranging protein which can come from the diet, body tissue (like muscles), or both.
weakness, headache and confusion. Some people with
hypoglycemia have symptoms but normal blood sugar. Hypoglycemia
may be caused by frequently changing from a low
carbohydrate diet to a diet with lots of sugar.
When a person rapidly eats lots of sugar, the pancreas gets a VERY URGENT message to secrete insulin. Lots of insulin is secreted and blood sugar plunges.
The cause of true hypoglycemia may be a tumor of pancreas or hepatitis of the liver or other disorder.
The DIAGNOSIS of Hypoglycemia (& diabetes) is the Glucose Tolerance Test.
E. Diabetes- is a chronic disease in which the body can no longer regulate glucose within normal limits, and high blood glucose levels (hyperglycemia) becomes chronic.
There are two types of diabetes, Type 1 and Type 2.
With both types of diabetes, glucose has trouble getting from the blood into the cell.
1. Type 1
diabetes can't produce enough insulin, so glucose can not enter cells.
Type 1 diabetes is classified as an autoimmune disease because the
body's immune system attacks and destroys the insulin-producing cells of
the pancreas. Therefore, type
1 diabetics must take insulin by
injection. Insulin cannot be taken in pill form because it's
composed of proteins which would be enzymatically digested by the
He quickly learned skills at managing his disease, including pricking his finger to check and chart blood sugar levels.
His brother, Spencer, also learned about giving injections, although Guy at times uses an insulin pump.
|2. Type 2
diabetes body cells become resistant or less responsive to insulin.
Approximately 90-95% of all cases of diabetes are classified as type 2.
Obesity is the number one risk factor for developing this
Type 2 diabetes is an advancement of insulin resistance. To read more about insulin resistance and type 2 diabetes check out the following website:
If you're interested below is a video that describes the causes and complications of type 2 diabetes a bit more.
Here is a link to the above video: https://www.youtube.com/watch?v=VLiTbb6MaEU
Problems for Type 1 and Type 2 diabetics come from long term high blood sugar (hyperglycemia). Chronic exposure to elevated blood glucose levels can lead to damage of both large and small blood vessels which in turn damages other body tissues. Having diabetes can increase a person's risk for developing:
4. Lifestyle choices can help prevent or control
Is a diabetics diet different than a non-diabetics diet?
There is no "Diabetic Diet". It starts with healthy eating, and diabetics can follow MyPlate recommendations just like non-diabetics.
People with diabetes do not need "special foods" but they do need to be aware of the total carbohydrates in their foods.
What is important for diabetics is that they try to eat about the same time each day, and to not skip meals. This will help diabetics control their blood sugar more easily.
Even though diabetics can have a hard time processing glucose, carbohydrates are still an important part of their diet. The key is moderation, and balance, something that is important to any healthy diet.
"There are many factors driving the growth in diabetes worldwide, but most experts agree that changes in lifestyle and diet are the chief culprits, in addition to genetic predisposition. As developing countries rapidly industrialize, people tend to do work involving less physical activity. At the same time, the availability of food that is cheap but high in calories becomes more common.
"The combination causes weight gain, which leads to greater risk of developing Type 2 diabetes, the most common form of the disease. The other form, Type 1, is responsible for 5 percent to 10 percent of cases and is not associated with behavior but is believed to stem almost entirely from genetic factors."
Watch the following video to learn more about the types of diabetes, risk factors and complications associated with diabetes, and how to prevent diabetes.
Here is a link to the above video:
END of Lecture 4B