Fifty years ago people ate most meals at home with their families and at a leisurely pace. They also ate more less-processed (fresh) foods.

Today, because of our fast-paced lives, we have less time to prepare food at home and consequently we more processed (fast food) foods.

Ethnic Heritage and Tradition have the strongest influence on our food choice. The least influential factor tends to be health/nutrition.

An example of this is malnutrition. Many of you will be surprised to hear that malnutrition includes two components: undernutrition (nutrient deficiency) and overnutrition (excess nutrient). You probably could have guessed the deficiency but not the excess, right?

This brings us to another topic called Nutrient Density. Nutrient density a measure of the nutrients a food provides compared with its caloric (energy) content.

Take a look at the next slide, which compares the nutrient density between French fries and broccoli.

Now, take a look at Table 1.4 to help you make better choices regarding the nutrient density of popular foods.

Risk Factors are behaviors that may increase or decrease the chance of developing a chronic disease.

Figure 1.2 on page 6 shows the 10 leading causes of death in America and their associated risk factors. We see that the 3 leading causes of death are linked with diet. It is compelling information and the reason why it is important to learn about nutrition.

The six classes of nutrients are merely introduced here. We will elaborate upon these nutrients; their chemistry (not so much), special features and functions, in subsequent lectures.

The slide below describes organic nutrients as those which are carbon containing. Though, as consumers, we tend to think of the word organic as describing a food substance that is free of pesticides, chemical fertilizers etc, in the world of science, organic means CARBON-CONTAINING. By scientific definition, all foods are organic. Notice that water and minerals, which is composed of oxygen and hydrogen, and are not organic.

It is important to remember that Energy = Calories and that only the energy-yielding nutrients provide calories and thus, true energy. The three energy-yielding nutrients are:

Despite what we read on vitamin/mineral packages or their advertisements, these nutrients do not provide usable energy. When asked why they take a multivitamin supplement, many people respond, "I didn’t have any energy". The only means of obtaining true energy (calories) is by eating carbohydrates, proteins and fat.

Note: Alcohol also provides plenty calories, but the calories are empty of nutrients.

The science of nutrition is the study of nutrients and the body's handling of these nutrients.

See the slide above for the scenario of nutrition research. First, someone asks a question or makes an observation about a nutrient. Then they construct a hypothesis (an educated guess) that may explain the observation. Research or experiments are then conducted to test the hypothesis about that nutrient. Data is collected and interpreted. A theory, based on this data, can be established.

Let’s take an example of vitamin C. Suppose I ask the question "Does vitamin C cure the common cold?" (No one has asked that before, right?) Maybe I hypothesize "Yes, in some populations". Now, I need to do my research studies on vitamin C. This is where there is much controversy in the marketplace regarding nutrition supplements.

I will refer to EPIDEMIOLOGICAL STUDIES often in the course. In these types of studies we look at huge populations of people, often, over long periods of time (sometimes centuries). These populations are not asked to make any lifestyle changes. We simply observe the current lifestyle and relate those lifestyle choices to an aspect of health.

An example of this type of research is the Mediterranean approach to eating (Olive oil and legumes). In the Mediterranean, individuals, despite their relatively high fat diets and high weights, tend to have the longest lifespan of any other world population.

When we read research studies we need to focus on the number of participants in the study and the time frame of the study. Also, important is whether or not the findings have been duplicated. If we can't repeat the study with the same findings, they may not be valid in their findings.

The slide below depicts the red flags for nutrition hype and quackery.

A checklist for identifying nutrition misinformation:

• Is something being sold? Yes
• Does the product or service offer a new rememdy for problems that are not easily or simply solved (e.g. obestiy, cellulite, arthritis, poor immunity, weak muscles, low energy, hair loss, wrinkles, aging, stress)? Yes
• Are such termas as "miraculous, magical, secret, detoxify, energy restoring, suppressed by organized medicine, immune boosting, or studies prove used? Yes
• Are testimonials, before and after photos or expert endorsements used? Yes
• Does the information sound too good to be true? Yes
• Is a money-back guarantee offered? Yes

In addition to the red flags, go to Table 1.6 and see how you can examine the evidence before you make your decision.

Through years of research, scientists have developed standards by which to define the amounts of energy and nutrients needed to best support health. These standards are constantly revised as we learn more about foods, nutrition, the environment and the human body.

You are probably most familiar with the standard called the Recommended Dietary Allowances (RDA). These are recommendations for the intake of calories and nutrients at risk for deficiency such as protein, vitamins, and minerals.

Note the slide below for the additional Dietary Reference Intakes and their definitions. These were designed to be used for planning and assessing diets of healthy people and to promote health as well as prevent chronic disease and nutrient deficiencies.

Lets take a look at how the RDA is set. The graphic below shows us the Nutrient RDA and the Energy RDA. The midpoint line on the bell curve of the graph represents the estimated average requirement. So, half of the population may require more than the midpoint quantity. The line to the right represents where the nutrient quantity is actually set. As the book describes, "The nutrient RDA are set high enough to cover nearly everyone's requirements."

This lecture provides the type of information the consumer needs to make sound food choices. We can discuss, with an individual, their clinical guidelines regarding nutrients but what really assists them is a more practical lesson in general dietary guideline. We must translate these guidelines into shopping for and preparing foods.

In your text, on page 40, you will find the most current dietary guidelines for Americans. Every 5 years the recommendations change. The purpose is to provide science-based advice to promote health and to reduce the risk for chronic diseases through diet and activity.

These guidelines have 23 key recommendations for all ages of healthy people and 18 recommendations for "special" populations who may have special dietary needs, like pregnant women.

• Make nutrient-dense choices
• Balance food and activity
• Limit nutrients that increase health risks (fat? salt?, ect)
• Keep food safe

• Basic product information
• Net contents of weight
• The date by which the product should be sold
• Address of the manufacturer
• A "Nutrition Facts" panel
• A list of ingredients

• Serving size
• Total calories
• Calories from fat
• Amount of nutrients per serving
• % Daily Value
• Ingredient listing

The quick guide to % Daily Value is a reference to show how the food fits into an overall diet. The %DV is the amount of a nutrient in a food as a percentage of the recommendation for a typical 200 calorie diet.

You will find this information on page 52. Please take the time to read the information and grasp an understanding of it. It is crucial to your ability to determine how a particular food will fit into your overall diet. Table 2.7 on page 53 discusses the standards that make up these Daily Values based on a 2000 calorie diet and a 2500 calorie diet.

The most vital information on any label, in my opinion is the ingredient listing. This is the bottom of the label colored in lavender. Ingredients are listed in descending order. You will want to notice the very tiny lettering! Look to see if there is anything "whole" in this product? Look at Figure 2.12. The first ingredient is water. What is the next ingredient??? Fructose!!! It is just another word for SUGAR.

Notice the slide below for a listing of those approved health claim topics.

For your information, I am also providing a glossary of descriptive terms used on food labels. This will assist you in shopping for healthy foods. See below.

Notice the next slide below lists the term "Lite or Light". This term may describe the color, texture or even taste of a product. When an olive oil lists the word "lite", it refers to light color or flavor, not fat or calories.

These are diet planning tools that sort foods of similar origin and nutrient content into groups and then specify that people should eat certain numbers of servings from each group.

Please go to www.MyPyramid.gov for a wealth of information regarding the new version of the pyramid. Once you get there, surf the site for a little while and play with the interactive portion of the website.

This is also the site you will go to when calculating your diet in relationship to nutrients during the rest of the semester for the Personal Diet Inventory Assignment.   

THE EXCHANGE LIST groups foods according to the energy yielding nutrients (Carbohydrate, Protein and Fat).

Please see page 60, in your text for the graphics regarding the Exchange List. I think you will find it helpful in understanding this food guide.

GRAINS: To make things so simple I tell clients and students to look for one word on the ingredient list and that word is "whole". When grain foods such as breads, cereals and crackers are refined, the bran and the germ are removed.

• FORTIFICATION is the addition of nutrients to a food that were either not originally present or present in insignificant amounts. A good example of a fortified food is orange juice fortified with calcium. Oranges are a poor source of calcium, in their natural form.
•  ENRICHMENT is the addition of nutrients to a food to meet a specified standard.

Fortified grains may be nutritious with respect to the nutrients added back, but can not provide the full spectrum of nutrients that a whole grain can. We can also bring up the relatively new area of Phytochemicals. These are beneficial substances in whole foods which are proving to be protective against degenerative diseases such as heart disease and cancer. These substances exist in good amounts in the whole grain but not in the refined form.

Please read grain food labels (breads, cereals, crackers) and look for the word "WHOLE". You want to read the ingredient list because, here, foods are listed in descending order or in order of predominance. Some cereal and cracker labels are very deceptive. They show graphics like the sunshine or a wheat field. When we check that label for the word "whole", it does not exist. A product may list "wheat" but if it does not specify "whole wheat" it is certainly a refined product.

• VEGETABLES: Again to keep things very simple, shop by color. The deeper the color the more nutritious. Sorry, but iceberg lettuce is not the greatest choice. Include dark green leafy things often. Fresh is best, then frozen and last is canned.
• LEGUMES: Replacement for meat, fish or poultry. Try the many varieties. When cooking from dry, soak overnight in baking soda (about 1 TBSP per lb of beans), discard soaking water before cooking rinse beans, add fresh water and cook until tender. This will decrease the most common compliant when eating beans: GAS.
• FRUIT: Again, variety is the key. Also, fresh is better than juice. Juice has no fiber. Fresh vs. canned. Canned fruits and vegetables can lose water-soluble vitamins.
• MEAT, FISH AND POULTRY: Choose the very lean and lean meats and you will obtain protein with little fat and cholesterol.
• MILK: Choose the nonfat and low-fat varieties.

• MOUTH AND SALIVARY GLANDS -Notice the slide below of the mouth and salivary glands. Salivary glands are located at the base of the tongue and release enough saliva to moisten each mouthful of food. Salivary glands are activated at the smell or even the mere thought of food. Saliva mixes with food to ease the passage of food into the esophagus. I remember learning in high school biology that digestion begins in the mouth. This is true only for carbohydrate. Amylase is secreted by the salivary glands and begins the digestive process of carbohydrate only. In the mouth, all foods are crushed into a course mash. This course mash forms what we call a bolus. The bolus is like a ball of chewed food. If small pieces of food were to travel from the mouth, we would choke on those small bits. We will talk about the function of saliva, later in the lecture, when we discuss the secretions of digestion.

• EPIGLOTTIS AND TRACHEA- You need to look in your book on page 66 for a graphic of the epiglottis and trachea. The epiglottis is cartilage in the throat that guards the entrance to the trachea (windpipe). The epiglottis prevents food and fluid from entering the trachea to prevent choking. You may have heard someone refer to a choking incident as food going down the wrong pipe. This wrong pipe is the trachea (windpipe or airway). When food is trapped in the trachea it blocks the airway and can cause severe choking and even death. On page 83, of the text, there is a discussion of First Aid for choking. It is important to master the Heimlich maneuver as a life saving measure. This involves abdominal thrusts which create pressure in the airway in order to dislodge the food.

The next slide shows some of the major digestive organs from the esophagus at the top to the anus at the bottom of the slide.

Graphic explained in detail below

• ESOPHAGUS-The long teal-colored pipe on the next slide is the esophagus. Some refer to this organ as the "food pipe". The bolus from the mouth slides down the esophagus into the stomach. Separating the esophagus from the stomach is the first of the sphincter muscles called the cardiac sphincter. (We will review all of the sphincter muscles a bit later)

• LIVER- Notice the liver on the slide. It is situated to the left of the stomach. Though the liver is not a holding vessel for food, it is an important organ in the digestive process, because it manufactures a secretion of digestion called bile. (Again, we will review the secretions of digestion in a bit). Bile is a detergent-like substance that digests fat.

• GALLBLADDER - Look at page 66 in your book to see the gallbladder. Again, this is not a holding vessel for food, but is the organ that store and concentrates bile until it is needed to help digest (emulsify) fat.

• STOMACH - Notice the orange stomach, on the slide. The stomach is a very muscular, elastic organ that expands and contracts with the presence and absence of food. The stomach grinds and churns swallowed food. Acids, enzymes and fluids in the stomach convert food into a semi-liquid mass that we now call chyme. Separating the stomach from the small intestine is the second in the series of sphincter muscles called the pyloric sphincter. This muscle closes behind the chyme and regulates the flow of chyme from the stomach into the small intestine.

• PANCREAS- See the pancreas on page 66 in your book. It is near the stomach region. It also is not a holding vessel for food but plays a very important role in the process. It manufactures enzymes that help digest all of the energy-yielding nutrients.

• SMALL INTESTINE- This organ can be seen on the slide below, in purple. The small intestine is about 10 feet long (coiled up tightly in the body) and is a major site for the digestion of food and the absorption of nutrients. This organ secretes enzymes that digest all of the energy-yielding nutrients to smaller particles. The small intestine is made of 3 parts: duodenum, the jejunum and the ileum. Separating the small from the large intestine is the third in the sphincter muscle series called the ileocecal valve. This muscle empties the content of the small intestine into the large intestine.

• LARGE INTESTINE (COLON) - Notice the large intestine, in turquoise, in the slide below. It completes the digestive process. The large intestine's job is to reabsorb water and minerals and pass undigested materials (fiber, bacteria and some water) to the rectum.

• RECTUM- This is the last part of the large intestine. It stores waste prior to elimination. The anus is the sphincter muscle that opens to allow for the passage of waste.

The digestive system is a very active system. As I mentioned, in the stomach, food is being churned and ground. This is facilitated by a muscular action. The small intestine is coiled so tightly that food needs to be pushed along to make it move into the large intestine. Again, this requires muscular actions called peristalsis, which controls the movement of these digestive organs.

• PERISTALSIS is a wavelike muscular contraction of the gastrointestinal tract that pushes the contents along. If you have ever seen a snake being fed a mouse, you have seen peristalsis in action. You can actually see the snake's body (which is a big muscle) in a wavelike motion digesting the mouse. Below is a graphic depiction of peristalsis occurring in the small intestine.

Sphincter muscles open and close in a rhythmic fashion and are located at various points along the digestive tract. These muscles basically prevent the contents of one organ from backing up into another organ - sort of like a valve.

For example, the cardiac sphincter, seen on page 84, Figure 3.6, prevents reflux (backflow) of the stomach contents back into the esophagus. This muscle separates the esophagus from the stomach. When the cardiac sphincter fails to do its job, the contents of the stomach spill back up into the esophagus causing discomfort or pain.

The non-clinical term for this is heartburn.

• SALIVA is secreted by the salivary glands and moistens food to ease swallowing. Saliva contains the enzyme, amylase, which breaks down carbohydrates. Saliva protects the tooth surfaces, and the linings of the mouth, esophagus and the stomach. Saliva helps protect the organs from their own secretions.

• GASTRIC JUICE is secreted by the stomach and kills most of the bacteria that enters the body through food. It contains hydrochloric acid and is very acidic! It provides for the partial breakdown of protein, preparing it for digestion. As you look at the graphic below, of the pH scale, you will see that gastric juice, in the stomach, is almost as acidic as battery acid.

• PANCREATIC JUICE is secreted by the pancreas and contains enzymes that breakdown carbohydrate, fat and protein. If you will again, check the pH scale below, you will see that this secretion is very neutral. It contains sodium bicarbonate and thus neutralizes the acid chyme (chyme is acid because it has been mixed with gastric juice in the stomach) before it makes its way into the small intestine.

• BILE is secreted by the liver and emulsifies (breaks down) fat into smaller particles which enzymes can attack. We will discuss bile in detail in our lipid chapter.

• PROTECTIVE FACTORS, otherwise known as good bacteria, grow in both small and large intestines. They prevent the establishment infectious bacteria. They defend against infectious bacteria and other foreign invaders.

The digestive organs have now done their part. The muscular actions discussed in the previous lecture have helped push the contents of food (chyme) down through the organs. The secretions of digestion have helped to break whole foods into their most elemental, singular forms. We are now ready for absorption.

The inner surface of the small intestine is wrinkled into hundreds of folds. From a microscopic view, we see that these folds consist of thousands of hair-like projections. These projections are called villi. Each of the villus (singular for villi) is covered with even smaller hair-like projections called microvilli.

The villi are lined by a thin muscular sheet and are in constant motion. The microvilli trap nutrient molecules and draw them in. The microvilli provide the absorptive surfaces that allow the nutrients to pass through to the body. The villi are selective about which molecules they will allow to pass through to the body. When a non-nutrient is seen by the small intestine, it is unrecognized and passes to the large intestine.

On page 89, you can find the four modes of absorption: Simple Diffusion, Osmosis, Facilitated Diffusion and Active Transport. The mode of absorption is determined by the size and type of nutrient molecule.

The Cardiovascular System carries the products of carbohydrate and protein digestion, most vitamins and the minerals from the digestive tract to the liver. (I will talk more about the liver in just a minute.) After going to the liver, the blood flows to the heart. See Figure 3.16 below.

Most of the products of fat digestion as well as the fat-soluble vitamins go first to the Lymphatic System but ultimately get transported to the blood circulatory system. Unlike nutrients that get transported directly by the blood circulatory system, the nutrients that are transported by the lymph bypass the liver at first and go to the heart. The heart pumps the nutrients to the cells of the body which need them. The remnants of the nutrients are then transported to the liver.

Notice the portal vein, in Figure 3.17, leads from the digestive tract to the liver. Lymph vessels bypass the liver and leads from the digestive tract straight to the veins to the right side of the heart. This blood will eventually be transported to the liver.

The liver is strategically located in the vascular system. It is the first organ that receives the materials that are absorbed by the digestive system. It acts as a gatekeeper to protect the heart and the brain from harmful substances. When people take in poisons that pass through the intestinal cells, the liver is the organ that suffers the damage. The liver takes on substances like alcohol and drugs before they can damage the heart and the brain. The liver can only take on so much. After years of abuse, it will begin to degenerate and will not be able to perform its job as gatekeeper.

Metabolism of Nutrients

Metabolism is the amount of energy (calories) your body burns to maintain itself. Whether you are eating, drinking, sleeping, cleaning etc... Your body is constantly burning calories to keep you going. Each nutrient plays a part in metabolism. If your diet is lacking in the right amounts of nutrients, metabolism will not occur properly. This can adversely affect you health. Protein, fat, and carbohydrates produce energy after they are broken down into glucose, fatty acids, and amino acids. The long-short of this is ATP - The energy source your muscles use for short bursts of power.

Homework: