Lipids and Proteins

Lipids

• Lipids are a diverse group of chemical compounds that do not readily dissolve in water.

  • This insolubility is due to their nonpolar nature, which contrasts with the polar nature of water.

  • They include fats (solid) and oils (liquid)

• They yield 9 kcal per gram, making them a high-energy source for the body.

• Lipids include triglycerides, phospholipids, and sterols, each with unique structures and functions.

• Triglycerides are the most common form of fat in foods and the body, serving as the primary storage form of energy.

Fatty Acids and Triglycerides

• Triglycerides consist of three fatty acids bonded to glycerol, a three-carbon alcohol. This structure allows for efficient energy storage.

• Fatty acids are long chains of carbons bonded together, with an alpha end (acid group) and an omega end (methyl group). The length and saturation of these chains affect the properties of the fat.

• Saturated fatty acids:

  • Solid at room temperature due to their straight structure, which allows them to pack tightly together.

  • More prevalent in foods of animal origin, such as butter, lard, and fatty meats.

• Unsaturated fatty acids:

  • Liquid at room temperature because their bent structure, due to the presence of double bonds, prevents tight packing.

  • More prevalent in foods of plant origin, such as olive oil, avocado oil, and nuts.

  • Can be cis or trans, depending on the orientation of the hydrogen atoms around the double bond. Cis fatty acids have hydrogens on the same side, while trans fatty acids have hydrogens on opposite sides. Trans fats are primarily artificial and have negative health impacts.

Saturated Fatty Acid Structure

• Carbons in the saturated fatty acid chain are connected by single bonds.

Monounsaturated Fatty Acid Structure

• A fatty acid with only one double bond is monounsaturated.

Polyunsaturated Fatty Acid Structure

• A fatty acid with more than one double bond is polyunsaturated.

Essential Fatty Acids

• Two fatty acids must be supplied by the diet: linoleic acid (omega-6) and alpha-linolenic acid (omega-3). These cannot be synthesized by the body.

• Other fatty acids and regulatory compounds can be synthesized from these essential fatty acids, highlighting their importance.

• Functions:

  • Form body structures, such as cell membranes.

  • Support immune and nervous systems by producing signaling molecules.

  • Produce regulatory compounds like eicosanoids and hormones, which are crucial for various physiological processes.

Omega-3 Fatty Acids

• The first double bond is located on the 3rd carbon from the omega (methyl) end. This structural feature defines their classification and influences their biological activity. Common omega-3 fatty acids include EPA and DHA, found in fish oil.

Triglycerides and Related Compounds

• Triglyceride: Glycerol + 3 fatty acids, the body's main form of fat storage.

• Diglyceride: Glycerol + two fatty acids, an intermediate product in triglyceride metabolism.

• Monoglyceride: Glycerol + one fatty acid, also an intermediate in fat digestion.

Phospholipids

• Glycerol + 2 fatty acids + phosphorus-containing compound, giving them both hydrophobic and hydrophilic properties.

• Synthesized by the body as needed for various functions.

• Component of cell membranes, forming a lipid bilayer that regulates the passage of substances into and out of cells.

Sterols

• Multi-ringed structure, unlike other lipids with long fatty acid chains.

• Cholesterol (found only in foods of animal origin) is essential for cell membrane structure and hormone synthesis.

• Phytosterols (found in foods of plant origin) can help lower cholesterol levels by interfering with cholesterol absorption.

Fatty Acids and Triglycerides in Food

• Protein foods group:

  • Low-fat: Kidney beans are a good source of protein with minimal fat.

  • Medium-fat: Loin and round cuts of beef provide protein and some fat.

  • High-fat: Nuts, marbled and processed meats are high in fat content.

• Dairy foods group:

  • Low-fat: Skim milk, low-fat yogurt are lower in fat while still providing essential nutrients.

  • Medium-fat: Whole milk or yogurt, cheese contain moderate levels of fat.

  • High-fat: Premium ice cream is high in fat and calories.

• Grains foods group:

  • Low-fat: Bread, cereal, plain pasta are generally low in fat.

  • Medium-fat: Bread with butter, pie crust add fat content.

  • High-fat: Pasta with alfredo sauce is rich in fat due to the sauce.

• Fruits and vegetables group:

  • Low-fat: Most fruits and vegetables are naturally low in fat.

  • Medium-fat: Baked potato with butter adds fat.

  • High-fat: Avocado, French fries are higher in fat; avocados due to their natural oil content and French fries due to frying.

Food Sources of Essential Fatty Acids

• Alpha-linolenic Acid (omega-3):

  • Flaxseeds are an excellent plant-based source.

  • Walnuts also provide omega-3 fatty acids.

  • Canola oil is commonly used in cooking.

  • Soybean oil is another good source.

  • Perilla seed oil is rich in omega-3s.

  • Chia seed oil is a concentrated source.

• Linoleic Acid (omega-6):

  • Safflower oil is a primary source.

  • Sunflower oil is another common source.

  • Corn oil is widely used.

  • Cottonseed oil is also a source.

  • Nuts and seeds provide omega-6 fatty acids.

  • Chicken contains linoleic acid.

Omega-3 Fatty Acids in Fish

• Atlantic salmon: 1.8 g

• Anchovy: 1.7 g

• Sardines: 1.4 g

• Rainbow trout: 1.0 g

• Coho salmon: 0.9 g

• Bluefish: 0.8 g

• Striped bass: 0.8 g

• Tuna, white, canned: 0.7 g

• Halibut: 0.4 g

• Catfish: 0.2 g

• Recommendation:

  • Consume two servings of fatty fish per week for optimal cardiovascular health. This helps ensure adequate intake of EPA and DHA.

Food Sources of Phospholipids

• Wheat germ

• Peanuts

• Egg yolks

• Soybeans

• Organ meats

• Lecithin is used as an emulsifier in food products to stabilize mixtures of oil and water.

Cholesterol Content of Foods

• Beef brains, cooked (3 oz): 2,635 mg

• Beef liver, braised (3 oz): 334 mg

• Egg yolk (1 large): 184 mg

• Shrimp, cooked (3 oz): 123 mg

• Beef, pot roast, braised (3 oz): 89 mg

• Chicken breast, skinless (3 oz): 85 mg

• Pork loin, roasted (3 oz): 69 mg

• Trout, broiled (3 oz): 63 mg

• Ice cream chocolate, regular (1 cup): 50 mg

• Tuna (3 oz): 42 mg

• Hot dog (3 oz): 33 mg

• Cheddar cheese (1 oz): 28 mg

• Whole milk (1 cup): 24 mg

• 1% milk (1 cup): 12 mg

• Fat-free milk (1 cup): 5 mg

• Egg white (1 large): 0 mg

Fat in Food: Satiety, Flavor, and Texture

• Fats slow the process of digestion, promoting satiety and helping to control appetite.

• Fats improve the flavor and texture of foods, making them more palatable.

Fat-Replacement Strategies for Reduced-Fat Foods

• Sugar, water or air, starch, protein, fiber are used to mimic the texture and mouthfeel of fats.

• Fat substitutes (engineered fats):

  • Examples: Olean® (olestra), Benefat® (salatrim). These provide fewer calories than regular fats.

Fat Rancidity Limits Shelf Life

• Oils decompose from breakdown of double bonds in unsaturated fatty acids by UV light or oxygen, leading to rancidity.

• Polyunsaturated fatty acids are more susceptible due to the presence of multiple double bonds.

• Produces unpleasant odor and flavor, making the food unappetizing.

Prevention of Fat Rancidity

• Add antioxidants: Vitamin E, BHA, BHT to scavenge free radicals and prevent oxidation.

• Hydrogenate oils to reduce the number of double bonds.

• Replace unsaturated fatty acids with saturated fatty acids, which are more stable.

• Decrease light exposure by using opaque packaging.

• Decrease oxygen exposure through vacuum sealing.

• Use tropical oils natural saturated fats, such as coconut oil and palm oil, which are less prone to rancidity.

Fat Digestion and Absorption

• Mouth: Lingual (salivary) lipase initiates the digestion of triglycerides.

• Stomach: Gastric lipase continues the breakdown of fats.

• Small intestine: Primary site for digestion and absorption.

  • Duodenum releases CCK to stimulate the release of bile and pancreatic enzymes.

  • Bile emulsifies fats, breaking them into smaller droplets.

  • Pancreatic lipase hydrolyzes triglycerides into monoglycerides and fatty acids.

  • End products: monoglycerides and fatty acids, which are then absorbed.

• Phospholipids are digested by phospholipases from the pancreas and intestinal cells.

• Cholesterol is digested by cholesterol esterase from the pancreas.

Absorption of Fatty Acids

• 95% of dietary fat is absorbed in the small intestine.

• Short- and medium-chain fatty acids are absorbed into the hepatic portal vein and transported directly to the liver.

• Long-chain fatty acids are absorbed into the lymphatic system before entering the bloodstream.

Carrying Lipids in the Bloodstream

• Lipoprotein: transport vehicle for lipids in the blood, allowing them to be transported in the aqueous environment of the bloodstream.

  • Core of lipids, including triglycerides and cholesterol.

  • Shell of protein, phospholipids, and cholesterol, which stabilizes the particle and allows it to interact with cells.

Major Lipoproteins in Blood

• Chylomicron:

  • Primary Component: Triglyceride, carrying mostly dietary fat.

  • Key Roles: Carries dietary fat from the small intestine to cells throughout the body.

• VLDL:

  • Primary Component: Triglyceride, but also contains cholesterol and protein.

  • Key Roles: Carries lipids made and taken up by the liver to cells.

• LDL:

  • Primary Component: Cholesterol, often referred to as "bad" cholesterol.

  • Key Roles: Carries cholesterol made by the liver and from other sources to cells. High levels can lead to plaque formation in arteries.

• HDL:

  • Primary Component: Protein, with smaller amounts of cholesterol and phospholipids. Often called "good" cholesterol.

  • Key Roles: Contributes to cholesterol removal from cells and, in turn, excretion of it from the body. High levels are associated with a lower risk of heart disease.

Roles of Lipids in the Body

• Provide energy, with 9 kcal per gram.

• Structural components of every cell, especially in cell membranes.

• Regulate cellular processes through hormones and signaling molecules.

• Insulating and protecting the body from injury by providing a cushion for organs.

Providing Energy

• Fatty acids are an important source of fuel for the body, especially during rest and low-intensity activity.

• Breakdown of fatty acids releases energy used to synthesize ATP (adenosine triphosphate), the body's energy currency.

• About half the energy used by the body at rest and during light activity comes from fatty acids.

Storage

Energy stored mainly in the form of triglycerides in adipose tissue, providing a reserve for when energy intake is insufficient.

Forming Body Structures

• Cell membrane:

  • Phospholipids form a bilayer, creating a barrier that controls what enters and exits the cell.

  • Cholesterol adds stability to the membrane, ensuring it remains flexible and durable.

• Nervous system:

  • Lipid is about 60% of the weight of the human brain, highlighting its importance.

  • Phospholipids and cholesterol are components of the myelin sheath, which insulates nerve cells and speeds up nerve impulse transmission.

Regulation and Communication

• Sterols are needed for hormone synthesis (estrogen, testosterone, vitamin D), which regulate a wide range of physiological functions.

• Essential omega-3 and omega-6 fatty acids are converted into eicosanoids.

  • Eicosanoids are chemical messengers that direct growth and development, immune function, and the central nervous system. They include prostaglandins, thromboxanes, and leukotrienes.

Total and Saturated Fat Intake

• Total Fat:

  • Acceptable Macronutrient Distribution Range: 20% to 35% of kcal from fat. This range supports overall health while minimizing the risk of chronic diseases.

• Saturated Fat:

  • Dietary Guidelines: limit saturated fat to less than 10% of total calories to reduce the risk of cardiovascular disease.

  • AHA: 5% to 6% for those at risk for or with cardiovascular disease to further lower LDL cholesterol levels.

Recommendations for Essential Fatty Acids

• Linoleic acid (omega-6):

  • Men: 17 g/d

  • Women: 12 g/d

• Alpha-linolenic acid (omega-3):

  • Men: 1.6 g/d

  • Women: 1.1 g/d

• Signs of essential fatty acid deficiency:

  • Skin becomes flaky and itchy due to impaired barrier function.

  • Wound healing may be slow because eicosanoids are needed for tissue repair.

  • May experience diarrhea due to altered intestinal permeability.

  • Hair may fall out or lose its pigment resulting in structural changes.

  • More vulnerable to infections because immune function is compromised.

  • Growth may be restricted among children, as these fatty acids are crucial for development.

Cholesterol Intake

• Dietary Guidelines and the AHA: set no specific limits on dietary cholesterol because it has less impact on blood cholesterol than saturated and trans fats.

• Dietary cholesterol has little impact on blood cholesterol levels for most people.

• Saturated and trans fat have the greatest impact on blood lipids by increasing LDL cholesterol.

Omega-3 Fatty Acid Intake

• Consume seafood 1 to 2 times per week to obtain adequate amounts of EPA and DHA.

• Excessive omega-3 fatty acid intake can cause bleeding and hemorrhagic stroke because they can reduce blood clotting.

American Heart Association’s Diet and Lifestyle Recommendations

• Aim to achieve and maintain a healthy body weight, blood lipid profile, blood pressure, and blood glucose levels to reduce the risk of cardiovascular disease.

• Mediterranean diet which is rich in fruits, vegetables, whole grains, and healthy fats.

Tips for Cutting Back on Saturated and Trans Fats

• Choose whole grains over refined grains.

• Consume a variety of colorful vegetables.

• Eat a wide array of fruits.

• Choose low-fat or fat-free dairy products.

• Select lean protein sources.

• Use healthy fats and oils in moderation.

Cardiovascular Disease

• Leading cause of death in North America and globally.

Development of Cardiovascular Disease

• Blood vessel is damaged by smoking, diabetes, high blood pressure, or infection, initiating the atherosclerotic process.

• White blood cells at the site of damage take up oxidized LDL and form an atherosclerotic plaque.

• As atherosclerotic plaque increases in size and stiffens, blood vessels become narrow and inflexible, reducing blood flow.

• A blood clot or rupture of the plaque can cause a blockage, leading to:

  • Myocardial infarction (heart attack): death of part of heart muscle due to lack of oxygen.

  • Cerebrovascular accident (stroke): death of part of brain tissue due to interrupted blood supply.

Plant Sterols for Cardiovascular Disease

• Clinically shown to reduce LDL (bad) cholesterol by blocking its absorption in the small intestine.

Medications to Lower Blood Lipids

• To lower LDL cholesterol: statins, resins, absorption inhibitors.

• To raise HDL cholesterol: niacin.

• To lower blood triglycerides: fibrates.

Surgical Treatment for Cardiovascular Disease

• Percutaneous transluminal coronary angioplasty (PTCA) to open blocked arteries.

• Coronary artery bypass graft (CABG) to bypass blocked arteries with healthy blood vessels.

Proteins

• Body made up of thousands of proteins that perform a wide variety of functions.

• Contains nitrogen, carbon, hydrogen, and oxygen, which distinguishes them from carbohydrates and fats.

• Functions: forms important structures like muscles and connective tissues, makes up key part of blood such as hemoglobin, regulates and maintains body functions through enzymes and hormones, provides essential nitrogen for synthesizing non-protein compounds, can fuel body cells when necessary.

Amino Acids—Building Blocks of Proteins

• 20 different amino acids make up all proteins, each with a unique side chain.

• 9 essential amino acids (must be consumed from diet):

• 11 nonessential amino acids (can be synthesized in the body):

• Typically supply 4 kcal per gram, similar to carbohydrates.

Essential Amino Acids

• Histidine

• Isoleucine

• Leucine

• Lysine

• Methionine

• Phenylalanine

• Threonine

• Tryptophan

• Valine

Nonessential Amino Acids

• Alanine

• Arginine

• Asparagine

• Aspartic acid

• Cysteine

• Glutamic acid

• Glutamine

• Glycine

• Proline

• Serine

• Tyrosine

Branched-Chain Amino Acids

• Leucine, isoleucine, and valine have branched side chains.

• Used by muscles for energy needs, especially during exercise.

• High amount in whey protein from milk, making it popular among athletes.

Essential Amino Acids

• Cannot be synthesized by humans in sufficient amounts or at all, must be included in the diet to ensure proper protein synthesis.

Limiting Amino Acid

• Essential amino acid in the lowest concentration in food or diet relative to body needs, which limits the synthesis of proteins requiring that amino acid.

Phenylketonuria (PKU)

• Genetic disease—tyrosine becomes conditionally essential because phenylalanine cannot be properly metabolized.

• Limited ability to metabolize phenylalanine to tyrosine due to a deficiency in the enzyme phenylalanine hydroxylase.

• Phenylalanine builds up to toxic levels in the blood, causing neurological damage.

• Disrupts brain function, leading to mental retardation if not managed through a special diet.

Protein Organization and Synthesis

• Proteins linked together by peptide bonds between the amino acids.

• Bonds form between amino group of one amino acid and acid (carboxyl) group of another.

  • Dipeptides, 2 amino acids.

  • Tripetides, 3 amino acids.

  • Oligopeptides, 4 to 9 amino acids.

  • Polypeptides, 10 or more amino acids.

Protein Organization

• Order of amino acids in a protein determines its ultimate shape and function.

• Protein’s final shape determines its function in the body, such as enzymatic activity or structural support.

Protein Synthesis

• Requires energy in the form of ATP.

• DNA contains coded instructions for protein synthesis.

• Copies of codes transferred to cytoplasm via mRNA (messenger RNA).

• Amino acids added one at a time with aid of transfer RNA (tRNA), which brings the correct amino acid to the ribosome.

• Polypeptide is released into the cytoplasm and processed further, folding into its functional shape.

Denaturation of Proteins

• Alteration of a protein’s three-dimensional structure, because of treatment by heat, enzymes, acid, alkaline solutions, and agitation.

• Reduces biological activity by disrupting the protein's shape.

Protein Quality of Foods

• Differs according to origin (animal or plant), individual amino acid composition, and level of amino acid bioactivity.

• Animal protein generally contains all nine essential amino acids in adequate amounts.

• Plant proteins in grains are often low in one or more of the nine essential amino acids.

Dietary Protein Quality

• High-quality (complete) proteins: contain ample amounts of all nine essential amino acids, supporting optimal protein synthesis.

• Lower quality (incomplete) proteins: low in or lack one or more essential amino acids, which can limit protein synthesis.

Digestible Indispensable Amino Acid Score (DIAAS)

• Advanced method for assessing protein quality of foods, focusing on amino acid digestibility.

• Determines amino acid digestibility in the small intestine, providing a more accurate measure of protein availability.

• Measures amounts of amino acids absorbed by body, reflecting their actual bioavailability.

Complementary Proteins

• Combining two food protein sources that make up for each other’s inadequate supply of specific essential amino acids to ensure adequate intake of all essential amino acids.

Animal Proteins

• Eating patterns rich in animal products are not recommended due to potential health risks.

• Potential to increase risk for cardiovascular and other diseases due to higher saturated fat and cholesterol content.

• Excessive intake of processed red meat is linked with colon cancer, highlighting the importance of moderation.

Food Protein Allergies

• Immune system mistakes food protein for harmful invader, triggering an allergic reaction.

• Reactions range from mild intolerance to fatal allergic reactions, depending on the severity of the allergy.

• Introducing allergenic foods early in life may prevent allergies but should be done under medical supervision.

Eight Foods Account for 90% of Food-Related Allergies

• Soy

• Peanuts

• Tree nuts

• Wheat

• Milk

• Eggs

• Fish

• Shellfish

Gluten Sensitivity—Celiac Disease

• Gluten is a protein found in certain grains (wheat, rye, barley), causing adverse reactions in sensitive individuals.

• Gluten sensitivity: incomplete gluten breakdown in the small intestine, leading to digestive symptoms.

• Celiac disease: inflammatory response to small peptides and amino acids.

  • Autoimmune response, genetic predisposition, causing damage to the small intestine

Digestion of Protein

• Protein denatured by cooking and acid in the stomach, unfolding the protein structure.

• Hormone Gastrin: released into the stomach and stimulates the release of acid and pepsin, preparing the protein for digestion.

• Pepsin: Enzyme produced by the stomach. Breaks polypeptide into shorter chains of amino acids, initiating protein digestion.

Digestion of Protein in the Small Intestine

• Release of hormone cholecystokinin (CCK) stimulates the release of pancreatic enzymes.

• Pancreatic enzymes are released into the duodenum, further breaking down peptides.

• Small peptides and amino acids are ready for absorption in the small intestine.

Protein Absorption

• Takes place at the microvilli surface and within absorptive cells lining the small intestine.

• Active absorption using many different amino acid transport mechanisms, ensuring efficient uptake.

• Amino acids are sent to the liver via the portal vein, where they are metabolized or distributed to other tissues.

Functions of Proteins

• Produce body components such as muscles, enzymes, and hormones.

• Maintain fluid balance by regulating the distribution of water in the body.

• Contribute to acid–base balance by acting as buffers.

• Form enzymes and hormones that regulate various physiological processes.

• Contribute to immune function as antibodies.

• Glucose production when carbohydrate intake is insufficient.

• Provide energy and satiety, helping to control appetite.

Producing Vital Body Structures

• Amino acids in cells used to form body proteins, which are essential for growth and maintenance.

Protein Turnover

• Turnover: breakdown and synthesis of proteins, allowing the body to adapt to changing needs.

• Amino acids can be recycled to synthesize new proteins or used for energy.

• If protein intake is low for a long period, rebuilding and repairing body proteins will slow down, leading to muscle loss and impaired function.

Maintaining Fluid Balance

• Proteins help regulate blood acid–base balance by acting as buffers.

• Protein pumps in cell membranes keep the blood slightly alkaline, essential for proper cellular function.

• Act as buffers to prevent drastic changes in pH.

Forming Hormones and Enzymes

• Amino acids used for the synthesis of many hormones, such as insulin and growth hormone.

• Almost all enzymes are proteins, catalyzing biochemical reactions in the body.

Contributing to Immune Function

• Key component of cells within the immune system, such as antibodies and cytokines.

• Low-protein status can turn an infection into a fatal disease due to impaired immune response.

Source of Energy: Forming Glucose

• Without enough carbohydrate, the liver produces glucose from amino acids, maintaining blood glucose levels.

• In starvation, amino acids from muscle tissue are converted into glucose, leading to muscle wasting.

Providing Energy

• Proteins supply little energy for a weight-stable person when carbohydrate and fat intake are adequate.

• Can provide energy during prolonged exercise and weight loss efforts when other fuel sources are depleted.

• Amino group from amino acid is removed, and the remaining carbon skeleton is metabolized for energy.

• Ammonia $NH_3$ is a resulting waste product that is converted to urea in the liver and excreted by the kidneys.

Protein Needs

• Protein balance or equilibrium is balancing protein intake with protein losses to maintain body protein stores.

• RDA: 0.8 gram of protein per kilogram of healthy body weight for sedentary adult, ensuring adequate protein for basic functions.

RDA for Protein

• Acceptable Macronutrient Distribution Range: 10% to 35% of total calories.

• Athletes: from 1.2 to 2 grams per kilogram of healthy body weight is to optimize athletic performance and muscle recovery.

• Excess protein cannot be stored as protein; it is converted to glucose or fat.

Protein Intake Recommendations: Dietary Guidelines for Americans

• Recommend a variety of protein foods: seafood, lean meats and poultry, eggs, legumes, nuts, seeds, and soy products to ensure a balanced intake of amino acids.

• Select from seafood or beans, peas, and lentils more often to help meet recommendations while still ensuring adequate protein consumption and reducing the intake of saturated fat.

Protein Requirements per Meal

• Maintain more equal distribution of protein at each meal to optimize muscle protein synthesis.

• Consume 20 to 30 grams of protein at each meal to maximize anabolic response.

• Protein at breakfast is especially critical to kickstart metabolism and support satiety throughout the day.

Protein Needs for Older Adults

• Increase daily protein intake to more than 1.0 gram per kilogram for older adults to prevent muscle loss and maintain function.

• Consume meals with greater than 20 grams of protein to stimulate muscle protein synthesis.

• Include more than 2.2 grams of leucine, a key amino acid for muscle growth.

Amino Acid Supplements

• Sometimes used by athletes and those trying to lose weight, but their benefits are often overstated.

• Overwhelms absorptive mechanisms in the small intestine, leading to imbalances.

• Most likely to cause toxicity: methionine, cysteine, and histidine, potentially causing adverse effects.

Protein-Calorie Malnutrition

• Somewhat rare in developed countries but can occur in specific populations.

• Significant problem in hospitals worldwide and in developing countries, especially among children.

Marasmus

• Starvation and insufficient protein and calories, leading to severe wasting.

Kwashiorkor

• Marginal amount of calories and insufficient protein, leading to edema and stunted growth.

The Emerging Field of Nutritional Genomics

• Nutritional genomics: interactions between nutrition and genetics; includes both nutrigenetics and nutrigenomics.

  • Nutrigenetics: the study of the effects of genes on nutritional health, such as variations in nutrient requirements and responsiveness to dietary modifications.

  • Nutrigenomics: the study of how food impacts health through its interaction with our genes and its subsequent effect on gene expression.

Why Do People Become Vegetarians?

• Ethics, religion, economics, and health are common motivations.

• Nutritional needs can be met with a vegetarian dietary pattern if planned carefully.

Good for Disease Prevention

• Positive impact on heart health due to lower saturated fat and higher fiber intake.

• Good source of fiber, vitamins, minerals, and phytochemicals, promoting overall health.

Vegan Diets

• Require complementary proteins to ensure adequate intake of all essential amino acids.

• Nutrient deficiency concerns: Vitamin B-12, iron, zinc, calcium, omega-3 fatty acids, which are often found in animal products.

Food Plan for Vegetarians Based on MyPlate

• Grains:

  • Lactovegetarian: 6 to 11 servings

  • Vegan: 8 to 11 servings

• Beans and other legumes:

  • Lactovegetarian: 2 to 3 servings

  • Vegan: 3 servings

• Nuts, seeds:

  • Lactovegetarian: 2 to 3 servings

  • Vegan: 3 servings

• Vegetables:

  • Lactovegetarian: 3 to 5 servings

  • Vegan: 4 to 6 servings

• Fruits:

  • Lactovegetarian: 2 to 4 servings

  • Vegan: 4 servings

• Dairy/Fortified soy milk:

  • Lactovegetarian: 3 servings

Energy Balance

Fake or Fact?

Dietary Patterns

• Over 70% of North American adults are overweight

• US adults gain about 1.1 to 2.2 pounds per year

• Estimate: by 2030, will see a 33% increase in obesity and 130% increase in severe obesity

• No quick cure for overweight or obesity

• Most reliable and successful weight loss comes from a:

  • commitment to lifestyle behaviors that improve dietary and physical acitivity patterns

  • combination of improve energy balance, increased physical activity, and behavior modification

Positive and Negative Energy Balance

Energy balance: Energy Input = Energy Output

• energy intake, in the form of food and beverages, matches the energy expended, primarily through basal metabolism and physical activity

Positive energy balance

• Energy intake is greater than energy expended

• Results in weight loss

1lb. weight loss = -3500kcal/week or -500kcal/day

Energy Intake

Energy needs met by dietary intake

• number of calories consumed each day

Availability of inexpensive, highly processed palatable food:

• In vending machines

• At social gatherings

• At fast-food restaurants

• In supersized portions

The average US adult is 10 pounds heavier than just 10 years ago

Estimating Caloric Content in Food

• Bomb Calorimeter measures kilocalorie content by burning dried portion of food

• Burning food raises temperature of water surrounding chamber holding food

• 1 kcal = amount of heat needed to raise the temperature of 1 kilogram of water by 1 degree Celsius

Energy Output

Thermogenesis:

• Body burns calories to produce heat

Body uses energy for three general purposes:

• Basal metabolism

• Physical activity

• Digestion, absorption, processing of ingested nutrients

• Small amount for adaptive thermogenesis

  • Production of heat in response to changes in dietary patterns or environmental temperature

Figure 7-5: Contributions to Energy Output

Basal Metabolism Rate (BMR): 60% to 80% of Total Energy Expenditure (TEE)

Factors That Increase BMR

• Acute illness or injury

• Certain medical conditions

• Excess thyroid hormones

• Greater body surface area (height, weight)

• Increased body temperature

• Lactation

• Lean body mass

• Periods of growth (pregnancy, infancy, and adolescence) significantly increase the body's demand for lipids and proteins, essential for tissue development and energy production.