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Questions and Answers
What is the recommended daily protein intake for most adults based on a body weight of 68 kg?
What is the recommended daily protein intake for most adults based on a body weight of 68 kg?
Which of the following statements about phospholipids is true?
Which of the following statements about phospholipids is true?
Which of the following foods is considered a complete protein source?
Which of the following foods is considered a complete protein source?
What is a known function of cholesterol in the body?
What is a known function of cholesterol in the body?
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Which of the following food sources is a rich source of sterols?
Which of the following food sources is a rich source of sterols?
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Which type of fatty acids is predominantly found in nuts and is considered beneficial?
Which type of fatty acids is predominantly found in nuts and is considered beneficial?
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What is a potential health benefit of consuming high-fat foods in the Mediterranean diet?
What is a potential health benefit of consuming high-fat foods in the Mediterranean diet?
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What is the recommended daily intake of linoleic acid for adult men aged 19-50 years?
What is the recommended daily intake of linoleic acid for adult men aged 19-50 years?
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How many essential amino acids must be obtained through diet?
How many essential amino acids must be obtained through diet?
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What percentage of daily energy intake is recommended for fat consumption in adults?
What percentage of daily energy intake is recommended for fat consumption in adults?
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Which group of athletes has a higher protein requirement, needing 1.2 to 1.7 grams per kilogram of body weight?
Which group of athletes has a higher protein requirement, needing 1.2 to 1.7 grams per kilogram of body weight?
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Which type of lipoprotein is referred to as ‘Loser’?
Which type of lipoprotein is referred to as ‘Loser’?
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What role does protein turnover play in the body?
What role does protein turnover play in the body?
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What is the significance of essential fatty acids like linolenic acid?
What is the significance of essential fatty acids like linolenic acid?
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How many grams of fat are in 400 calories, considering there are 9 kcal per gram of fat?
How many grams of fat are in 400 calories, considering there are 9 kcal per gram of fat?
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Which of the following is NOT a characteristic of high-fat foods in the Mediterranean diet?
Which of the following is NOT a characteristic of high-fat foods in the Mediterranean diet?
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What is a suggested portion size for nuts and seeds?
What is a suggested portion size for nuts and seeds?
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Which of the following is NOT a benefit associated with fish consumption?
Which of the following is NOT a benefit associated with fish consumption?
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During what critical time in life is increased protein intake particularly important?
During what critical time in life is increased protein intake particularly important?
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Which vitamin is specifically noted as important for pregnant women?
Which vitamin is specifically noted as important for pregnant women?
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What is a major argument against taking vitamin supplements?
What is a major argument against taking vitamin supplements?
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What is the approximate percentage of body weight that is made up of water?
What is the approximate percentage of body weight that is made up of water?
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Which of the following does not have a safe level of supplementation?
Which of the following does not have a safe level of supplementation?
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What is a common misconception about dietary supplements?
What is a common misconception about dietary supplements?
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What is the primary role of fats in the body?
What is the primary role of fats in the body?
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Which type of fatty acid is solid at room temperature and generally increases blood cholesterol levels?
Which type of fatty acid is solid at room temperature and generally increases blood cholesterol levels?
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Which of the following fats is considered a 'good fat' that can improve blood cholesterol levels?
Which of the following fats is considered a 'good fat' that can improve blood cholesterol levels?
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What are essential fatty acids that must be provided by the diet?
What are essential fatty acids that must be provided by the diet?
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What is a significant health risk associated with trans-fatty acids?
What is a significant health risk associated with trans-fatty acids?
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What is a common source of polyunsaturated fatty acids?
What is a common source of polyunsaturated fatty acids?
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Which of the following is true about the energy provided by fats?
Which of the following is true about the energy provided by fats?
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What function do fats serve besides being a source of energy?
What function do fats serve besides being a source of energy?
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Study Notes
Why We Need Fat
- Lipids are a major source of energy for the body.
- They play a role in performing muscular work.
- Lipids are the chief storage form for energy from excess food intake.
- They are essential for building cell membranes.
- They help cushion vital organs and insulate against temperature extremes.
- Lipids are essential for the transport of fat-soluble vitamins (ADEK), phytochemicals, and their absorption.
- The body converts lipids into other vital substances like bile, vitamin D, and hormones.
Dietary Fat
- Fat provides concentrated energy with 9 kcals per gram.
- It contributes to the taste and smell of food.
- Fat stimulates appetite and promotes a feeling of fullness called satiety.
4 Types of Lipids
- Triglycerides are the most common type of lipid, found in butter, margarine, and oils.
- Phospholipids are a type of lipid that are soluble in both water and fat.
- Sterols are lipids without fatty acids, composed of rings of carbon and hydrogen.
- Waxes are lipids with various functions, including protection.
Triglycerides
- Triglycerides are composed of one glycerol molecule and three fatty acids.
- They are a storage molecule for energy, containing twice the storage capacity of carbohydrates.
Saturated Fatty Acids (SFA)
- SFAs are fully saturated with hydrogen atoms.
- They are solid at room temperature.
- They are mainly found in animal sources like milk, cream, butter, cheese, bacon, meat, eggs, poultry, and ice cream.
- Some plant sources include nuts and tropical oils like coconut oil.
- They increase blood cholesterol levels, potentially raising the risk of heart disease and type 2 diabetes.
Monounsaturated Fatty Acids (MUFA)
- MUFAs have one double bond in their structure.
- They are not fully saturated with hydrogen atoms.
- They are considered "good fats."
- Plant sources include olive and canola oil, avocados, and nuts.
- MUFAs are associated with improved blood cholesterol levels and decreased risk of heart disease and type 2 diabetes.
Polyunsaturated Fatty Acids (PUFA)
- PUFAs have more than one double bond in their structure.
- They are primarily found in plant-based foods and oils like corn, soybeans, and safflower oil.
- PUFAs are associated with improved blood cholesterol levels and decreased risk of heart disease and type 2 diabetes.
- There are two essential fatty acids PUFAs that the body cannot produce: linoleic acid and linolenic acid.
Trans-Fatty Acids
- Trans-fatty acids are produced through the addition of hydrogen to vegetable oil, creating partially hydrogenated oils (PHOs).
- They are unhealthy fats that increase LDL ("bad") cholesterol and raise the risk of heart disease.
- Trans-fatty acids are commonly found in fried foods like French fries and doughnuts, as well as baked and packaged foods like crackers, pastries, pie crusts, pizza dough, microwave popcorn, cookie dough, stick margarine, and shortening.
- The FDA has ruled that food companies can no longer add PHOs to their products, effective by 2018.
- Trans-fatty acids naturally present in animal products like beef and dairy may have some health benefits.
Phospholipids
- Phospholipids are composed of glycerol, two fatty acids, and a phosphate molecule.
- They are soluble in both water and fat.
- Food sources include egg yolks, liver, soybeans, peanuts, and wheat germ.
- They act as emulsifiers, such as in salad dressing.
- The important phospholipid, lecithin, helps in transporting lipids.
- Phospholipids are synthesized by the body and are not considered essential.
- They are a major component of cell membranes.
Sterols
- Sterols are lipids that lack fatty acids and are composed of rings of carbon and hydrogen.
- They function as hormones, carrying chemical messages within the body.
- Examples include those involved in skin production of vitamin D, precursor sex hormones like estrogen and testosterone, and are important for brain health.
- Sterols can be found in both animal and plant products: meat, poultry, fish, and eggs.
Cholesterol
- The body produces a sufficient amount of cholesterol.
- It is essential for maintaining cell membrane fluidity and flexibility.
- Cholesterol is a precursor for the biosynthesis of all other hormones.
- Lipoproteins (LDL and HDL) act as "taxi cabs" and are responsible for transporting cholesterol and fat to and from cells.
- Low-density lipoproteins (LDL) are viewed as the "loser" since they carry cholesterol to tissues, potentially leading to plaque buildup in arteries.
- High-density lipoproteins (HDL) are considered "helpers" as they remove cholesterol from tissues and transport it back to the liver for processing.
- Food sources include animal products: meat, poultry, fish, and eggs
Recommendations for Fat Intakes
- The Dietary Reference Intakes (DRI) and Acceptable Macronutrient Distribution Range (AMDR) recommend a healthy range of 20-35% of daily energy from fat.
- It is recommended to limit saturated fat intake to less than 10% of total calories.
- For adults aged 19-30 years, the recommended AI for essential fatty acids in grams per day are:
- Linolenic acid: 1.6 g (men), 1.1 g (women)
- Linoleic acid: 17 g (men), 12 g (women)
Monitoring Your Fat Intake
- To calculate your daily fat intake in calories:
- Multiply your daily calorie needs by the percentage of fat you want to consume.
- For example, if you need 2000 calories and aim for 20% fat: 2000 x 0.20 = 400 kcals.
- To calculate your daily fat intake in grams:
- Divide the number of calories from fat by 9 (kcals per gram of fat).
- For example, 400 kcals / 9 = 44 grams of fat.
Lipoproteins and Heart Disease Risk
- LDL and HDL differ in size, density, function, and their impact on inflammation.
- LDLs are associated with an increased risk of heart attacks.
- Cholesterol testing is recommended to assess your heart disease risk.
High-Fat Foods of the Mediterranean Diet
- Olive oil is a key component of the Mediterranean diet.
- It is associated with potential health benefits, and darker olive oil (extra virgin) is generally considered better.
- It is important to be cautious with portion sizes due to its high calorie content.
- It should not be considered a "magic potion" for health.
Features of the Mediterranean Diet
- The Mediterranean diet focuses on whole foods, including:
- Fatty fish
- Nuts like walnuts and almonds
- The diet is associated with potential health benefits.
The Proteins and Amino Acids
- Proteins are organic molecules composed of amino acids.
- The body needs 20 different amino acids. These amino acids act as building blocks for tissues, like muscles.
- 9 amino acids are essential and must be obtained from dietary sources.
Importance of Proteins
- The body requires daily protein intake to build new cells.
- Protein turnover is a continuous process involving breakdown, recovery, and synthesis of proteins.
Functions of Proteins in the Body
- Proteins are essential for the formation and repair of tissues, including muscle, bone, skin, and hair.
- They play a role in enzyme production, which catalyzes biochemical reactions.
- They are involved in hormone production, regulating various bodily functions.
- Proteins carry oxygen in the blood (hemoglobin) and nutrients to cells.
- They help maintain fluid balance and regulate blood pressure.
- Proteins are also crucial for a healthy immune system.
Food Protein: Need and Quality
- The Recommended Dietary Allowance (RDA) for protein is 10-35% of total daily energy intake.
- Most adults need 0.8 grams of protein per kilogram of body weight.
- Athletes generally require higher protein intakes:
- Power athletes (strength or speed): 1.2-1.7 grams per kilogram per day
- Endurance athletes: 1.2-1.4 grams per kilogram per day
Complete Proteins
- Complete proteins contain all nine essential amino acids in proportions that the body needs.
- Examples include animal foods, except gelatin, as well as eggs, quinoa, and soybeans.
Limiting Amino Acids in Plant Foods
- Some plant foods lack certain essential amino acids in sufficient quantities.
- You can combine different plant-based foods to ensure you obtain all essential amino acids.
Food Protein: Legumes and Nuts
- Legumes like beans, lentils, and tofu are good sources of protein and can be meat alternatives.
- Nuts and seeds are excellent sources of protein and monounsaturated fatty acids (MUFAs).
- They make great snacks or additions to meals.
- It's important to watch portion sizes due to their high fat and calorie content (1/4 cup of nuts and seeds, or 2 tablespoons of nut butter).
Evaluating Protein Supplements and Amino Acid Supplements
- Protein supplements do not improve performance and are not effective for weight loss.
- The body is designed to work optimally with whole protein sources.
- Amino acid supplements are not recommended as there is no safe level of supplementation.
Food Protein: Fish
- Aim for two servings of fish per week.
- Fish are excellent sources of omega-3 fatty acids, reducing the risk of heart disease.
- Good choices include mackerel, trout, salmon, and sardines.
- Prepare fish using healthy methods like baking, broiling, grilling, or poaching.
Positive Health Aspects of the Meat Eater's Diet
- Adequate protein intake is crucial during critical life stages:
- Pregnancy and infancy
- Childhood
- Adolescence
- Aging and illness
Positive Health Aspects of Vegetarian Diets
- Vegetarian diets may be associated with other positive health behaviors, including:
- Reduced risk of obesity
- Improved blood lipid profiles
- Lower blood pressure
- Decreased cancer risk
Planning a Vegetarian Diet
- It is vital to ensure adequate intake of crucial nutrients when planning a plant-based diet, including:
- Protein
- Iron
- Zinc
- Calcium
- Vitamin B12
- Vitamin D
- Omega-3 fatty acids
Vitamins, Minerals, and Water
- It's important to understand the role of vitamins, minerals, and water in maintaining overall health.
The Fat-Soluble Vitamins
- Fat-soluble vitamins (ADEK) are stored in the body and do not need to be consumed daily.
- They are found in various food sources and are considered "essential."
- Excessive intake can lead to toxicity.
- Different fat-soluble vitamins have distinct roles within the body.
When Vitamin Supplements are Needed
- Supplements can be beneficial for specific individuals:
- Pregnant women: Supplements of vitamin B12, iron, and folate support red blood cell production.
- Individuals unable to produce intrinsic factor: May require vitamin B12 supplements (injections) as they cannot absorb it from food.
- Dieters, Anorexia, Bulimia: May require supplementation due to dietary restrictions.
- Lactose-intolerant individuals: May need vitamin D supplementation.
- Illness or surgery: May lead to nutrient deficiencies that require supplementation.
Arguments Against Taking Supplements
- Food is generally a safer and more ideal source of nutrients than supplements.
- Supplement users are more prone to exceeding recommended intakes.
- Supplements can be contaminated or contain harmful contaminants.
- Misinformation about supplements can be life-threatening.
- Supplements offer a false sense of security and can mask underlying health problems.
- Whole foods provide a wider range of nutrients, including antioxidants and fiber.
- Always consult a healthcare professional before taking supplements.
Water
- Water comprises about 60% of an individual’s body weight.
- Water content varies across different tissues, with brain and muscle having higher concentrations.
- Water is critical for numerous body processes:
- Transporting nutrients and oxygen to cells.
- Regulating body temperature.
- Removing waste products.
- Lubricating joints.
- Maintaining electrolyte balance.
Water Balance
- Body water is constantly being lost and replaced through various routes (urine, sweat, respiration).
- Daily fluid intake should match fluid output to maintain water balance.
Effects of Dehydration
- Mild dehydration can cause fatigue, headaches, and constipation.
- Severe dehydration can lead to dizziness, confusion, and heat exhaustion.
- Chronic lack of fluid can result in kidney stones, constipation, and other health problems.
Major Electrolytes
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Electrolytes are minerals that carry an electrical charge when dissolved in water.
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They play a vital role in maintaining fluid balance, nerve function, and muscle contraction.
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Key electrolytes include:
- Sodium
- Potassium
- Chloride
- Magnesium
- Calcium
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It is important to consume adequate electrolytes through diet and beverages, especially during exercise or in hot weather.
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