Food Choices: Nutrients and Nourishment

Ask yourself: Why do you eat the way you do? What food choices do you make? Why do you make those choices? Do you use food for reasons other than simply gaining nutrients? What are your food preferences? Where did you get these preferences? How much of this is inborn? How much of this is voluntary?

Biologists consider eating to be a “first-level imperative”. That is: Our bodies know it is essential for our survival, so our brains and hormones have evolved to drive us to be sure we eat.

Biologists consider eating to be a “first-level imperative”. That is: Our bodies know it is essential for our survival, so our brains and hormones have evolved to drive us to be sure we eat. However, the environments in which we now live are very different than the ones in which we evolved. Our brain chemistry and hormones continue to drive us to make choices to meet the nutritional needs of our evolutionary ancestors, so our eating patterns and food choices no longer always serve our needs. Our nutritional needs have changed, but our food choices have not.

Think back ~ 20,000 years: - Food was difficult to obtain - Few foods were available - Not all foods were available at all times - Foods easily spoiled - Foods contamination was common - People in non-tropical areas had to survive periods of starvation

Think back ~ 20,000 years: - Food was difficult to obtain - Few foods were available - Not all foods were available at all times - Foods easily spoiled - Foods contamination was common - People in non-tropical areas had to survive periods of starvation Now: - Food is easy to obtain - Many foods are available - Almost all foods available year-round - Food easily preserved - Food contamination is rare - Seasonal starvation is very rare

We eat more food in total and more types of foods We continue to seek high calorie foods (fats, carbohydrates) We continue to seek high salt foods We continue to store calories as fat Obtaining food requires less exercise

Even just half a century ago: More than a billion people were undernourished Less than 100 million people were obese Now: 1.6 billion people are overweight or obese 1.5 billion people have hypertension 250 million people have diabetes We eat more food in total and more types of foods We continue to seek high calorie foods (fats, carbohydrates) We continue to seek high salt foods We continue to store calories as fat Obtaining food requires less exercise

(1.6 billion people are overweight or obese 1.5 billion people have hypertension 250 million people have diabetes) Even so, food availability remains uneven: In many parts of the world healthy foods are unavailable or too expensive Climate change and war have destroyed croplands Food storage/preservation not always available So malnutrition still exists in many places

So: When we talk about nutrition, it is much more complex than just eating food. The science of nutrition helps us improve food choices by: 1. Understanding types & amounts of nutrients we need 2. Knowing the best food sources for those nutrients 3. Recognizing helpful and harmful components of food By making better choices, we can: 1. Improve our health 2. Reduce risk of disease 3. Increase longevity

Objectives for This Topic : You should be able to: - Understand and discuss factors which influence the food choices you make - Be able to assist others in understanding the food choices they make - Understand the six basic groups of nutrients, how they are classified, and the basic function of each one in human nutrition (we will go into detail on the functions of each nutrient in future lectures) - Be able to calculate the calorie content of different nutrients in your diet - Begin to be able to analyze the relationships between nutrition, health, and disease.

1. Sensory Influences: Taste Sweet, sour, bitter, salty, umami Smell Texture Color, moisture, and temperature Many things influence what foods we choose: Influences on Food Choices

2. Physiological changes Accompany aging process Teeth and gum deterioration Bone loss Diminished taste sensitivity Many things influence what foods we choose: Influences on Food Choices

Many things influence what foods we choose: 3. Cognitive influences Habits Comfort/discomfort foods Cravings Advertising and promotion Social factors Nutritional value and health beliefs Influences on Food Choices

4. Environmental Influences: Economic factors Lifestyle Culture Religion The “American diet” Many things influence what foods we choose: Influences on Food Choices

4. Environmental Influences: a. Economic factors: Many things influence what foods we choose: Limited finances shift food choices Costs of production / transportation affect food availability Influences on Food Choices

4. Environmental Influences: b. Lifestyle Where you live and climate Fast-paced society Eating away from home Convenience foods Prepared vs “from scratch” food Many things influence what foods we choose: Influences on Food Choices

4. Environmental Influences: c. Culture & Religion Regional foods (often based on available ingredients) Cultural / religious traditions Preservation techniques Many things influence what foods we choose: Influences on Food Choices

4. Environmental Influences: d. The “American diet” Many things influence what foods we choose: “Typical” is as diverse as Americans themselves Heavy on meat and potatoes Heavy on fried foods Light on fruits and whole grains More cereals, snack foods, soft drinks, noncitrus juices Influences on Food Choices

Food and Nutrients Regardless of WHY we choose the foods we do, they serve the same purpose: To provide the cells of our bodies with the nutrients they need to survive, reproduce, and carry on their normal functions.

Food = mixture of many different things Nutrients = chemicals in food which our cells need The Nutrients These have three general functions: - They supply energy for processes such as growth, movement, electrical signalling, metabolism - They provide the building blocks for making the structures of our cells and our bodies - They regulate body processes such as metabolism, growth, membrane transport, cellular communication

Food also contains things which are not nutrients: flavors and colors additives such as caffeine, nitrates phytochemicals undigestible material The Nutrients

Food also contains things which are not nutrients: flavors and colors additives such as caffeine, nitrates phytochemicals undigestible material It contains bacteria viruses mold pollen etc. It can contain toxic substances: pesticides mercury bis-phenols dioxin arsenic lead The Nutrients

Six classes of nutrients: Carbohydrates Lipids (fats and oils) Proteins Vitamins Minerals (ions, electrolytes) Water The Nutrients

Some of these are classified as: Macronutrients (things you need a lot of) Carbohydrates, lipids, and proteins Micronutrients (things you need small amounts of) Vitamins and minerals Organic nutrients (contain carbon) Carbohydrates, lipids, proteins, and vitamins Inorganic nutrients Minerals and water The Nutrients

The most important nutrient, by far, is water Most other nutrients are dissolved in it Forms fluid compartments of the body Regulates temperature Transports nutrients and wastes Commonly available: food & beverages The Nutrients

Carbohydrates = Sugars and starches Primary functions: energy source Food sources: Grains Vegetables Legumes Fruits Dairy products The Nutrients

Small subunits called monosaccharides (primarily glucose) hook together in large, branching chains. Carbohydrates = Sugars and starches Our digestive systems break those down so we can use the monosaccharides The Nutrients

Lipids = fats & oils, plus cholesterol and steroids Primary functions: energy source, form membranes steroid hormones Food sources: Fats and oils Meats Dairy products Some plant sources The Nutrients

Lipids = fats & oils Small subunits called fatty acids hook onto glycerol to form diglycerides and triglycerides. Our digestive systems break those down so we can use the fatty acids and glycerol. The Nutrients

Proteins Primary functions: structural – hold things together membrane channels enzymes antibodies Food sources Meats Dairy products Grains, legumes, vegetables The Nutrients

Proteins (also known as “peptides”) Our digestive systems break those down so we can use the amino acids. Small subunits called amino acids hook onto long, unbranching chains. The Nutrients

Vitamins: Primary functions: Regulate & assist with metabolic reactions Food sources: All food groups Classified as: Fat-soluble (A, D, E, K) Water-soluble (B vitamins, C) The Nutrients

Minerals (some also known as “ions” or “electrolytes”) r Functions: Carry electrical signals Regulate water movement Enzyme cofactors Food sources: All food groups Na +, K +, Ca ++, Mg ++, Mn ++, Fe +++, Zn ++, Cu ++, P, Cl -, S –, I - etc. The Nutrients

One of the most important roles of nutrients is to provide energy for cells of the body. Large molecules (“macromolecules”) in our diet are broken down by the digestive system into smaller molecules which can be absorbed and transported in the blood to those cells throughout the body. Within the cells, those smaller molecules are further broken down to release the energy they contain. The Nutrients

That energy released from foods is measured in calories (“c”) or kilocalories (“kcal” or “C”). Definitions: 1 calorie is the amount of energy needed to raise the temperature of one gram (one milliliter) of water by 1 o C. 1 kilocalorie is 1,000 calories. The Nutrients

The body normally avoids using proteins to produce energy, and alcohol (I hope) is not a major nutrient for you, so in reality your body depends on carbohydrates and lipids for its energy needs. We call these fuel molecules. The Nutrients

It’s also not surprising, then, that when you ingest more calories than you immediately need, the excess is stored as lipids and carbohydrate which can then be later used as fuel molecules when needed. The Nutrients

You can calculate the energy available from foods: For Example: 1.If you consume a breakfast that contains 100 grams of carbohydrate, 25 grams of protein, and 30 grams of fat, how many kilocalories did you eat? The Nutrients

You can calculate the energy available from foods: For Example: 1.If you consume a breakfast that contains 100 grams of carbohydrate, 25 grams of protein, and 30 grams of fat, how many kilocalories did you eat? 100 g carbohydrate x 4 kcal/g = 400 kcalories 25 g protein x 4 kcal/g = 100 kcalories 30 g fat x 9 kcal/g = 270 kcalories TOTAL = 770 kcalories The Nutrients

You can calculate the energy available from foods: For Example: 2. If you consume a breakfast that contains 100 grams of carbohydrate, 25 grams of protein, and 30 grams of fat, what percentage of your calories came from fat? from carbohydrate? The Nutrients

You can calculate the energy available from foods: For Example: 2. If you consume a breakfast that contains 100 grams of carbohydrate, 25 grams of protein, and 30 grams of fat, what percentage of your calories came from fat? from carbohydrate? 270 Kcal 770 Kcal 400 Kcal 770 Kcal Fat: =.35 = 35% Carbohydrate : =.52 = 52% The Nutrients

You can do it in reverse: If you know your caloric intake and how those calories should be distributed, you can calculate the quanties of each food component: For example: If you need a total of 2,200 kcal/day To limit fat intake to 30% of total energy intake: 2,200 kcal food x 0.30 = 660 kcal from fat 660 kcal from fat / 9 kcal/g = 73.3 g of fat allowed per day The Nutrients

This, of course, is where food labels are useful: They tell you how much of each component that food contains. This, of course, is not limited to fuel molecules. The Nutrients

Be food smart. For both yourself and your patients: Know what foods are ingested Know why you chose those foods Know what those foods contain Know the caloric content of those foods The Nutrients