Nutrients and Their Energy Values

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Questions and Answers

Which mineral is necessary for the synthesis of thyroid hormones?

Calcium

Magnesium

Zinc

Iodine (correct)

What is a major dietary source of iron?

Milk

Bread

Rice

Legumes (correct)

What is the primary function of zinc in the body?

Cofactor for digestive enzymes (correct)

Electrolyte balance

Component of hemoglobin

Oxygen transport

Which mineral is associated with the maintenance of tooth structure?

Fluorine Signup and view all the answers

What can excessive consumption of sodium lead to?

Fluid retention and high blood pressure Signup and view all the answers

The deficiency of which mineral is linked to muscle pain and potential heart muscle deterioration?

Selenium Signup and view all the answers

Which mineral acts as an enzyme cofactor in iron metabolism and melanin synthesis?

Copper Signup and view all the answers

What is a common symptom of zinc deficiency?

Growth failure and skin abnormalities Signup and view all the answers

Which of the following minerals is not typically harmful when consumed in moderate amounts?

Sodium Signup and view all the answers

Which mineral is primarily involved in glucose and energy metabolism?

Chromium Signup and view all the answers

What is the primary role of carbohydrates in the body?

Providing ATP for energy Signup and view all the answers

Which of the following nutrients is NOT classified as a macronutrient?

Vitamins Signup and view all the answers

What is the primary dietary source of complete proteins?

Animal products Signup and view all the answers

Excess glucose can be converted into which form for later use?

Glycogen or fat Signup and view all the answers

Water-soluble vitamins are characterized by which of the following?

Excreted in urine when in excess Signup and view all the answers

Which statement about lipids is accurate?

They are essential for stabilizing cell membranes. Signup and view all the answers

Which vitamin is synthesized by intestinal bacteria?

Vitamin K Signup and view all the answers

What percentage of total caloric intake should fats represent in a balanced diet?

20–35% Signup and view all the answers

Which nutrient is primarily needed for the synthesis of steroid hormones?

Cholesterol Signup and view all the answers

What is the recommended daily intake of carbohydrates as a percentage of total calories?

45–65% Signup and view all the answers

What is a primary function of dietary fiber?

Providing roughage and facilitating defecation Signup and view all the answers

Which of the following components is key to solubilizing fat-soluble vitamins in the gut?

Lipids Signup and view all the answers

Which condition indicates a positive nitrogen balance?

Muscle gain Signup and view all the answers

Which essential fatty acid is an omega-6 fatty acid?

Linoleic acid Signup and view all the answers

Study Notes

Part 1-Nutrients

Nutrient: A substance in food needed for growth, maintenance, and repair.
Five categories of nutrients.
Three macronutrients (carbohydrates, lipids, and proteins) form the majority of the diet.
Two micronutrients (vitamins and minerals) are also important, but in smaller amounts.
Most nutrients are used for metabolic fuel or building molecules and cells.
Water accounts for roughly 60% of the food volume.
Essential nutrients (approximately 40 molecules) must be consumed in the diet.
The body can't produce essential nutrients on its own.
Body cells, especially liver cells, can convert one molecule type to another.
This allows the body to adapt to varying food intakes.

Part 1-Nutrients (Energy Value)

Energy value of nutrients is measured in kilocalories (kcal).
One kcal is the amount of heat needed to raise the temperature of 1 kg of water by 1°C.
1 kcal = 1 calorie.
Carbohydrates and proteins provide 4 kcal/g, while lipids provide almost 9 kcal/g.
MyPlate guidelines are shown as portions on a dinner plate.
Basic Dietary Principles:
- Eat only what you need
- Eat plenty of fruits, vegetables, and whole grains
- Avoid junk food

Carbohydrates

Dietary sources: Mostly plants (except milk sugar (lactose) and small amounts of glycogen).
Sugars (monosaccharides and disaccharides): fruits, sugarcane, sugar beets, honey, and milk.
Starch (polysaccharide): grains and vegetables.
Insoluble fiber: present in vegetables and increases stool bulk aiding in defecation.
Soluble fiber: found in apples and citrus, reduces blood cholesterol levels.

Carbohydrates (Uses in the body)

Glucose: the carbohydrate molecule used by cells to produce ATP.
Fructose and galactose are converted to glucose by the liver before entering circulation.
Many cells use fats for energy, but neurons and red blood cells mostly rely on glucose.
Excess glucose is converted to glycogen or fat for later use.
Other uses: building nucleic acids (with pentose sugars), and cell's glycocalyx (with short-chain sugars).

Carbohydrates (Dietary Requirements)

Recommended daily carbohydrate intake is 45–65% of total calories.
Typical American adults consume about 46% of their calories from carbohydrates.
Diets should primarily include complex carbohydrates from whole grains and vegetables instead of simple carbohydrates.
Large amounts of refined, sugary foods contribute to obesity and nutritional deficiencies.
Starchy foods (e.g., rice, pasta, breads) are often less expensive than high-protein foods.

Lipids

Dietary sources: Primarily triglycerides (neutral fats) in saturated, trans, and unsaturated forms.
Saturated fats:Meat, dairy, some tropical plants (e.g., coconut)
Trans fats:hydrogenated oils (e.g., margarine and shortening)
Unsaturated fats:seeds, nuts, olive oil, and most vegetable oils
Cholesterol:egg yolk, meats, organ meats, shellfish, and milk products
The liver manufactures approximately 85% of the blood's cholesterol.
Two essential fatty acids synthesized by the liver (linoleic acid (omega-6) and linolenic acid (omega-3)).

Lipids (Uses in the body)

Adipose tissue: provides cushioning, insulation, and energy storage.
Phospholipids: essential components of myelin sheaths (neurons) and cell membranes.
Cholesterol: stabilizes cell membranes and is a precursor of bile salts and steroid hormones.
Prostaglandins: regulatory molecules made from linoleic acid involved in smooth muscle contraction, blood pressure regulation, inflammation.
Triglycerides: major energy source for skeletal muscle and liver cells.
Help absorb fat-soluble vitamins.

Lipids (Dietary Requirements)

Fats should represent 20–35% of total caloric intake (typically 40% in American diets).
Limit saturated fats to 10% or less of total fat intake.
Cholesterol can be synthesized by the body and isn't required in the diet.
Often recommended to keep cholesterol intake as low as possible, especially for individuals with high blood cholesterol levels.
High cholesterol levels are associated with cardiovascular disease.

Proteins

Dietary sources: primarily animal products (eggs, milk, fish, meats, soybeans) .
Legumes, nuts, and cereal grains contain incomplete proteins that are low in one or more essential amino acids.
Ingesting combinations of cereal grains and legumes provides all essential amino acids.

Essential Amino Acids

Essential amino acids are a small percentage of the total recommended protein intake.
- Histidine and arginine are essential for infants, but not adults.
Incomplete proteins from different sources (e.g., corn and beans) can be combined in one meal to provide all essential amino acids.

Proteins (Nitrogen Balance)

Homeostatic state: rate of protein synthesis equals rate of protein breakdown and loss.
Positive nitrogen balance: synthesis exceeds breakdown (normal in growing children and pregnant women, tissue repair)
Negative nitrogen balance: breakdown exceeds synthesis (occurs during stress, burns, infection, injury; low dietary protein intake).

Proteins (Dietary Requirements)

Essential amino acids are obtained from the dietary intake.
The amount of protein needed depends on age, size, metabolic rate, and current nitrogen balance.
A rule of thumb suggests a daily intake of 0.8 g of protein per kg of body weight.

Vitamins

Vitamins are organic compounds needed in small amounts.
Not an energy source; needed for macronutrient use.
Coenzymes or parts of coenzymes that carry out biochemical reactions when combined with enzymes during use of nutrients like glucose.
Made in the body or from ingested sources.
Vitamin D is made in the skin.
Vitamins B and K are synthesized by intestinal bacteria.
Beta-carotene from carrots can be converted to vitamin A.
A balanced diet avoids deficiencies.

Vitamins (Types)

Two types of vitamins based on solubility (Water-soluble, and Fat-soluble).
Water-soluble vitamins (e.g., B complex and C) are absorbed with water and are not stored in the body; excess can be excreted.
Fat-soluble vitamins (e.g., A, D, E, and K) are absorbed with lipids in the intestines and can be stored in the body.

Minerals

Seven minerals needed in moderate amounts, plus trace amounts of others.
(Calcium, phosphorus, potassium, sulfur, sodium, chlorine, and magnesium)
Like vitamins, minerals work with nutrients to support bodily functions.
Mineral incorporation makes body structures stronger.
Most minerals are ionized or bound to organic compounds to create phospholipids, hormones, and other proteins.
Iron is part of hemoglobin, which binds oxygen; sodium and chloride are essential electrolytes; iodine is needed for thyroid hormone synthesis.
Uptake and excretion are balanced to prevent excessive mineral accumulation.
Natural sodium is beneficial. Processed foods add high amounts of sodium contributing to fluid retention and high blood pressure.

Part 2-Metabolism

Metabolism: the total sum of all biochemical reactions in the body.
Metabolism involves the building up (anabolism) of compounds and the breaking down (catabolism) of compounds.
Body requires energy even when resting, used for essential functions like breathing and absorbing nutrients from food.

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Description

This quiz covers the essential nutrients needed for growth, maintenance, and repair, along with their energy values. Learn about the five categories of nutrients, their sources, and how they contribute to metabolic processes. Test your knowledge on macronutrients, micronutrients, and the importance of water in your diet.