Nutrition

Western Perspective

Nutrients

• A nutrient is any substance the body can use to obtain energy, synthesize tissues, or regulate functions.

• Nutrients provide the fuel to do physical work and perform metabolic functions.

• Nutrients are necessary for normal growth and development.

Nutrients

• Nutrients regulate hundreds of thousands of body processes.

• Essential nutrients are substances that must be obtained from the diet because the body cannot make it or because the body cannot make adequate amounts of it.

• The minimum diet for human growth and development must supply about 45 essential nutrients.

Classes of Nutrients

• Carbohydrates• Lipids (fats and oils)• Proteins• Vitamins• Minerals• Water

Nutrients

• To define a nutrient we focus on what happens in its absence.

• A deficiency of a nutrient will cause an adverse change in health.

Nutrients

• Replacing the deficient nutrient should restore health if the nutrient is supplied before permanent damage is done.

• Other substances in food (i.e. caffeine, phytochemicals, and fiber) affect our health, but do not fit the classical definition of a nutrient.

Functions of Nutrients

• Provide fuel or energy• Regulate body processes• Contribute to body structures

Nutrient Function

• Virtually all nutrients regulate body processes and contribute to body structures.

• Only the nutrients protein, carbohydrate, and fat are sources of energy.

Micro vs. Macro Nutrients

• The body needs large quantities of carbohydrate, protein, and fat; therefore, these are called macronutrients.

• The body needs much smaller quantities of vitamins and minerals; therefore, these are called micronutrients.

Organic vs. Inorganic

• Carbohydrates, lipids, proteins, and vitamins are all organic.

• Minerals and water are inorganic.• The inorganic nutrients are simpler structures.

Water is a very simple structure. Minerals are single elements, although they are often consumed as part of larger compounds.

Organic vs. Inorganic

• Organic nutrients have more complex structures.

• Carbohydrates, lipids, and proteins are broken down into simpler building blocks before they are absorbed in the small intestines.

• Vitamins are elaborately structured compounds.

Nutrients in Food

• It is rare for a food to contain just one nutrient.

• Foods contain mixtures of nutrients.• Typically, one nutrient such as protein,

carbohydrate, or fat will be predominant in the food.

Carbohydrates

• Carbohydrates are a large group of compounds, including sugars, starches, and dietary fibers.

• Carbohydrate literally means “hydrate of carbon”.

• Carbohydrates are made of carbon, hydrogen, and oxygen.

• They are a major source of fuel for the body.

Dietary Sources of Carbohydrates

• Carbohydrates are the starches and sugars found in grains, vegetables, legumes (dry beans and peas), and fruits.

• Dairy products have some carbohydrates, but there are practically none in meats.

Glucose

• Ingested carbohydrates are converted into glucose in the gastrointestinal system.

• Glucose is a simple sugar compound.• Glucose is found in the blood and serves as a

primary source of energy for cells and tissues.

Lipids

• Lipids are fats and oils.• Fat-like substances such as cholesterol and

phospholipids also fall into this category.• Lipids, like carbohydrates, contain carbon,

hydrogen, and oxygen.

Lipid Uses

• Triglycerides (fats) are also a major fuel source for the body.

• Triglycerides, cholesterol, and phospholipids provide structure for body cells, carry fat soluble vitamins (A,D,E, and K), and cholesterol is a building block for many hormones.

Dietary Sources of Lipids

• Lipids are obtained through the fats and oils we use to cook foods.

• Lipids are naturally occurring in meat and dairy products.

• Plant sources of lipids include coconut, olives, and avocado.

Proteins

• Proteins are organic compounds consisting of smaller building blocks called amino acids.

• In addition to carbon, hydrogen, and oxygen, proteins contain nitrogen.

• The amino acids that we obtain from dietary protein combine with the amino acids made in the body to make hundreds of different proteins.

Function of Proteins

• Proteins are utilized to build and maintain body structure.

• Proteins can be used for energy.• Enzymes are protein structures that regulate

chemical reactions in the body.

Dietary Sources of Proteins

• Meat and diary products are the most concentrated sources of protein.

• Grains, legumes, and vegetables all contribute protein to the diet.

• Fruits contribute negligible amounts of protein.

Vitamins

• Vitamins are organic compounds necessary for promotion of reproduction, growth, and maintenance of the body.

• Vitamins are required in miniscule amounts.• Vitamins are not broken down for energy;

however, they do help to extract energy from carbohydrates, proteins, and fats.

Fat Soluble Vitamins

• Vitamins A, D, E, and K are the fat soluble vitamins.

• Fat-soluble vitamins are stored in larger quantities in the body than the water soluble vitamins.

• Fat soluble vitamins can be toxic in high doses.

Water Soluble Vitamins

• The water soluble vitamins include vitamin C, and eight B vitamins: thiamin (B1), riboflavin (B2), niacin (B3), pyridoxine (B6), cobalamin (B12), folate, pantothenic acid, and biotin.

• Water soluble vitamins are much less likely to produce toxicity; however, pyridoxine and niacin can in very high doses.

Dietary Sources of Vitamins

• Vitamins are abundant in fruits and vegetables, but they are also found in meats, grains, legumes, dairy products, and fats.

• A well balanced diet can provide the necessary nutrients and eliminate the need for supplementation.

Minerals

• Minerals are simple, inorganic substances needed for growth and regulation of body processes.

• At least 16 minerals are known to be essential to health.

Minerals

• Some of the more prominent minerals are sodium, chloride, potassium, calcium, phosphorous, magnesium, and sulfur. These minerals are needed in relatively large quantities and are referred to as macrominerals.

• The other minerals are needed in very small amounts and are referred to as microminerals or trace minerals.

• Iron, zinc, copper, manganese, molybdenum, selenium, iodine, and fluoride are trace minerals.

Functions of Minerals

• Minerals can be found in structural roles (i.e. calcium, phosphorous, and fluoride in bones and teeth.

• Minerals have regulatory roles such as muscle contraction and fluid balance.

Dietary Sources of Minerals

• Minerals are abundant in both plant and animal sources.

• Mineral deficiency is uncommon, except for calcium and iron deficiency.

Water

• Water is the most important nutrient.• Water is one of the simplest nutrients.• The human body is nearly 60% water.

Water

• Most food products contain water.• Fruits and vegetables are especially high in

water.• Water helps to regulate body temperature,

lubricate the joints, transport nutrients, transport wastes, etc.

Nutrients and Energy

• One of the primary reasons we eat food is to obtain energy.

• Carbohydrates, lipids (triglycerides only), and proteins are the nutrient sources that provide energy.

• Alcohol can also be used as an energy source.

Calories

• In nutrition, we speak of the potential energy stored in foods in terms of heat units called kilocalories (1,000 calories).

Calories

• One kilocalorie (kcal) is the amount of energy (heat) required to raise the temperature of 1 kilogram (kg) of water by 1⁰ Celsius.

• Calorie is the general term for energy in food and used synonymously with the term energy. It is often used instead of kilocalorie on food labels, in diet books, etc.

Energy in Various Foods

• Carbohydrate 4kcal of energy per gram.• Protein 4kcal of energy per gram.• Alcohol 7kcal of energy per gram.• Fat 9kcal of energy per gram.

Calculate the Total Energy in kcal

• Bagel plus 1.5 ounces of cream cheese• 39 grams of carbohydrate• 10 grams of protein• 16 grams of fat

Percentages of Calories in Food

• Current health recommendations suggest limiting fat intake to no more than 30% of total caloric intake for the day.

Phytochemicals

• Phytochemicals are substances in plants that may possess health-protective effects, even though they are not essential for life.

• Thousands of componds, pigments, and natural anti-oxidants have been identified in plants.

Phytochemicals

• Phytochemicals have been shown to protect against heart disease, hypertension, cancer, and diabetes among other things.

• Phytochemicals modify hormone effects and neutralize free radicals, which helps protect against cancer.