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Questions and Answers
What is the recommended dietary allowance (RDA) for phosphorus?
What is the recommended dietary allowance (RDA) for phosphorus?
Which of the following symptoms is associated with sodium deficiency (hyponatremia)?
Which of the following symptoms is associated with sodium deficiency (hyponatremia)?
What is a primary function of potassium in the body?
What is a primary function of potassium in the body?
Which of the following foods is a poor source of phosphorus?
Which of the following foods is a poor source of phosphorus?
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What typically causes hyponatremia?
What typically causes hyponatremia?
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How do sodium and potassium work together in the body?
How do sodium and potassium work together in the body?
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What is a potential effect of phosphorus toxicity?
What is a potential effect of phosphorus toxicity?
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Which food is known to be a high source of sodium?
Which food is known to be a high source of sodium?
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Which condition is primarily related to calcium deficiency in conjunction with Vitamin D deficiency?
Which condition is primarily related to calcium deficiency in conjunction with Vitamin D deficiency?
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How does bioavailability of calcium from plant sources compare to that from animal sources?
How does bioavailability of calcium from plant sources compare to that from animal sources?
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What factor can dramatically increase the absorption of calcium in the body?
What factor can dramatically increase the absorption of calcium in the body?
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What is the maximum recommended daily intake of calcium to prevent toxicity?
What is the maximum recommended daily intake of calcium to prevent toxicity?
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Which demographic is most likely to lose bone mass rapidly due to hormonal changes?
Which demographic is most likely to lose bone mass rapidly due to hormonal changes?
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Which mineral is known for its role in preventing goiter and thyroid dysfunction?
Which mineral is known for its role in preventing goiter and thyroid dysfunction?
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What condition is characterized by muscle spasms due to acute calcium deficiency?
What condition is characterized by muscle spasms due to acute calcium deficiency?
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What is a key factor that can inhibit iron absorption from plant sources?
What is a key factor that can inhibit iron absorption from plant sources?
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What are common symptoms of iron deficiency?
What are common symptoms of iron deficiency?
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How does the bioavailability of heme iron compare to non-heme iron?
How does the bioavailability of heme iron compare to non-heme iron?
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Which factor is not known to negatively influence iron absorption?
Which factor is not known to negatively influence iron absorption?
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What can be a consequence of iron overload in the body?
What can be a consequence of iron overload in the body?
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What is a primary source of heme iron?
What is a primary source of heme iron?
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What is the recommended dietary allowance (RDA) for iron in adult females?
What is the recommended dietary allowance (RDA) for iron in adult females?
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Which of the following foods is the best non-heme iron source?
Which of the following foods is the best non-heme iron source?
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How does iron play a role in immune function?
How does iron play a role in immune function?
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Study Notes
Water
- The body needs more water than any other nutrient.
- One can survive a deficiency of other nutrients for months or years, but only a few days without water.
- A lack of water alters the body's metabolism in less than a day.
- Water makes up approximately 60% of an adult's body weight.
- Water is found in blood vessels and cells, and is a component of the chemical structure of cells, tissues, and organs.
- Water participates in many chemical reactions.
Water: The Most Essential Nutrient
- Water makes up a large portion of every cell, tissue, and organ (~60-70% of body weight).
- Bone contains >20% water, muscle ~75% and teeth ~10%.
- Losing 10% of body water is serious, and losing 20% can be fatal.
- Water is crucial for every living cell and process within the body.
Why Is Water the Most Indispensable Nutrient?
- Water delivers nutrients and removes waste from cells.
- It is the body's cleansing agent.
- Water is a nearly universal solvent.
- Water's incompressibility provides lubrication and cushioning.
- Water is vital for thermoregulation.
- Water intake needs to balance water loss.
Water's effect on the Body
- Water moistens tissues like those in the mouth, eyes, and nose.
- It protects body organs and tissues.
- Water helps prevent constipation.
- Water dissolves minerals and nutrients making them accessible to the body.
- Water carries nutrients and oxygen to cells.
- Water lubricates joints and reduces burden on kidneys and liver.
- Water helps maintain body temperature.
Deciding How to Hydrate
- Drinking water is linked to lower calorie intake and healthier diets, including more fruit and vegetables.
- Replacing sugary drinks with water for a year can lead to significant calorie savings (e.g., 6,084 grams of sugar = 24,336 calories).
Signs of Dehydration
- Thirst is an initial sign.
- Other signs include stronger thirst, discomfort, loss of appetite and increasing hemoconcentration.
- Less movement, flushed skin, impatience and feeling tired/weary.
- Tingling in limbs, stumbling, headache and heat exhaustion.
- Labored breathing, dizziness, and bluish coloring of the skin.
- Indistinct speech, increasing weakness and confusion.
- Muscle cramps, inability to balance, delirium, and decreased blood volume.
- Severe dehydration can lead to risk of death, particularly with illness or extreme heat.
Water Intoxication
- Hyponatremia is a condition characterized by low sodium concentration in the blood (below 135 millimoles per liter).
- Normal sodium concentration ranges from 135 to 145 millimoles per liter.
- Severe cases of hyponatremia can cause water intoxication, symptoms include headache, fatigue, nausea, vomiting, frequent urination, and mental disorientation.
- Rapid and severe hyponatremia can lead to brain swelling, seizures, coma, respiratory arrest, brain stem herniation, and death.
Minerals - an overview
- Minerals are chemical elements required in small quantities for body growth, repair, and various vital functions.
- Minerals are considered inorganic because they are not typically bonded to carbon.
- Minerals are essential for numerous body functions, including metabolism, muscle movement, and growth.
Mineral Bioavailability
- Some minerals compete for the same absorption sites, so megadosing one mineral can impede the absorption of another.
- High-fiber diets can reduce the absorption of certain minerals (iron, calcium, zinc, and magnesium).
- Substances like phytate and oxalate in some foods bind to minerals, hindering their absorption.
- Factors like acidity of the intestinal environment, person's need and other competing minerals affect mineral bioavailability.
Classification of Minerals
- Minerals can be grouped into major minerals (present in high concentrations) and micro/trace minerals (present in lower concentrations).
- Major minerals include sodium, potassium, magnesium, calcium, phosphorus, sulfur, and chloride.
- Micro/trace minerals include chromium, manganese, iron, cobalt, molybdenum, copper, zinc, fluoride, iodine, selenium, silicon, tin, arsenic, and nickel.
- Trace contaminants like lead, mercury, and aluminum are also present.
Calcium
- RDA (Recommended Dietary Allowance): 600 mg/day for adults and 1200 mg/day for pregnant and lactating women.
- Functions: Bone and tooth formation; blood clotting; muscle contraction; nerve impulse transmission;
- Sources: Milk, dairy products, cereals, millets, green leafy vegetables, nuts, and legumes.
- Bioavailability from plant sources is lower due to certain binders.
- Deficiency can cause rickets, osteomalacia, and osteoporosis.
- Toxicity is possible with high doses (>2500 mg/day) and can cause kidney stones, joint and soft tissue damage, and bradycardia.
Bone Mass and Osteoporosis
- Peak bone mass is typically achieved by age 30.
- People with high peak bone mass at age 30 have a lower risk of osteoporosis.
- Bone loss begins around age 30 and accelerates after menopause.
- People with low peak bone mass are more likely to develop osteoporosis by age 60.
- Osteoporosis is characterized by bone loss, making bones brittle and susceptible to fracture.
- After menopause women tend to lose bone mass at 3-5% annually.
Tetany
- Tetany is a condition characterized by muscle spasms, often in the hands and feet, and sometimes the larynx (voice box).
- It's often related to mineral deficiencies, especially calcium.
Calcium Absorption
- Calcium absorption depends on Vitamin D.
- High phosphorus intake, presence of oxalates and phytates, low estrogen levels and high sodium can hinder absorption.
- Adequate calcium and phosphorus ratio (1:1–2:1) is crucial for optimal absorption and function.
Phosphorus
- RDA: 600–700 mg/day.
- Functions: Aids bone formation and maintenance; supports metabolism;
- Sources: Milk, meat, poultry, fish, eggs, legumes, fruits, and vegetables.
- Deficiency is rare but can cause muscular weakness and poor bone maintenance.
- Toxicity (rare): high doses can lead to a decreased absorption of other minerals (calcium and magnesium).
Sodium
- RDA: 2 to 3 grams/day; higher for physical laborers.
- Functions: Acid-base balance; water balance; muscle contraction; nerve impulse transmission.
- Sources: Table salt, MSG, baking powder, baking soda, milk, milk products, green leafy vegetables, bakery products, processed foods.
- Deficiency is rare; excess can lead to high blood pressure.
Deficiency of Sodium
- Sodium deficiency (hyponatremia) is rare in healthy individuals.
- This can occur with excessive water intake, excessive sweating (prolonged), vomiting, diarrhea, and the use of some diuretics.
- Symptoms include headache, muscle cramps, fainting, fatigue, disorientation, nausea, vomiting, dizziness, apathy, exhaustion, an electrolyte imbalance, drowsiness, and possibly coma.
Potassium
- RDA: 2–3 grams/day.
- Functions: Maintains acid-base balance; water balance; regulates muscle activity and nerve impulses; and counteracts the effect of sodium.
- Sources: Fruits (bananas, oranges), vegetables (potatoes, tomatoes), dairy products, legumes, meats.
- Deficiency (hypokalaemia) rarely seen, symptoms are muscle cramps, rapid heart rate, loss of appetite, weakness and nausea.
- Excess (hyperkalaemia) can cause a slow heart rate, mental confusion, and weakness possibly leading to coma.
Magnesium
- RDA: Women—350 mg/day; Men—400 mg/day.
- Functions: Involved in the metabolism of fats, carbs and proteins, forms bones and teeth, helps nerve transmission and aids muscle relaxation.
- Sources: Nuts, legumes, whole grains, green leafy vegetables (like spinach), soybeans, chocolate, seafood.
- Refined foods are poorer sources.
- Deficiency causes irritability, tetany, weakness, and hyperreflexia.
Zinc
- RDA: 5–12 mg/day.
- Functions: Cofactor for over 100 different enzymes; aids in protein synthesis; promotes normal growth and sexual development; enhances immune function; and affects taste and smell.
- Sources: Meat, milk, liver, poultry, seafood, legumes, nuts, whole grains, greens.
- Deficiency causes delayed wound healing, loss of appetite, dwarfism, impaired sexual development, rashes, diarrhea, loss of hair, and hinders growth in children and often accompanied by malnutrition.
- High doses can suppress the immune response.
Iron
- RDA (Children 1–17 years old) 9–32 mg/day; Adult males 17 mg; Adult females 21 mg, Pregnancy 35 mg.
- Functions: Essential for formation of haemoglobin; helps in carrying oxygen; development of the brain and aids regulation of body temperature.
- Sources: Liver, meat, legumes, poultry, dark green leafy vegetables, broccoli, peas, dried fruits, potatoes, eggs, whole grain cereals and jaggery.
- Bioavailability of iron from animal (heme) foods is higher than from plant foods.
- Iron deficiency causes low haemoglobin level, low oxygen carrying capacity, lethargy, feeling weak, listlessness and often causes infections.
Iron Toxicity
- Iron absorption is challenging to regulate; and large doses can produce dangerous levels of iron in the body.
- Hemochromatosis, a genetic disorder, causes excessive iron absorption, damages cells and tissues, and can cause serious conditions, like liver damage, liver cirrhosis and cancer.
Iodine
- RDA: 150 mcg/day for adults and 25 mcg more for pregnancy/lactation.
- Functions: Crucial for thyroid hormone synthesis, normal growth and development, and regulating metabolism.
- Sources: Iodized salt, sea foods, cod liver oil, and in smaller amounts in milk, meat, vegetables and cereals.
- Deficiency leads to goiter, retarded development, impaired mental function, increased rate of abortions, and still births and cretinism (stunted growth, dwarfism, mental deficiency).
Fluoride
- RDA: 3–4 mg/day.
- Accepted level in water: 1 ppm is ideal.
- Functions: Aids in the formation of tooth enamel and increases resistance to dental cavities, strengthens bones.
- Sources: Fluoridated water, toothpaste, sea fish, cheese, tea.
- Deficiency can lead to dental caries (cavities).
- Excess fluoride results in fluorosis (mottled teeth and painful dense bones).
Copper
- RDA: 1.5–3 mg/day for all ages.
- Functions: Essential for hemoglobin formation; helps in iron absorption; part of many enzymes and assists in energy production and collagen synthesis.
- Sources: Meat, shellfish, liver, legumes, nuts, whole grain cereals, dried fruits.
- Deficiency is associated with iron deficiency anemia and PEM and causes poor growth.
Cobalt
- RDA: Not clearly determined.
- Functions: Component of vitamin B12, promotes RBC production.
- Sources: Animal foods.
- Deficiency is not usually seen in humans but is evident in animals.
Chromium
- RDA: Not known.
- Functions: Improves glucose uptake and aids in insulin synthesis.
- Sources: Meats, whole grains, cheese, and vegetables (GLVs).
- Deficiency can result in difficulty maintaining normal blood glucose levels.
Selenium
- RDA: Not known.
- Functions: Part of the antioxidant system, helps in antibody production and thyroid hormone synthesis; aids in protection against cell damage.
- Sources: Meats, organ meats, eggs, whole grains.
- Deficiency can cause muscle pain, muscular weakness, and a type of heart disease.
Molybdenum
- RDA: Not clearly defined.
- Functions: Assists in metabolic reactions through enzyme activity.
- Sources: Beef, kidney, liver, milk, legumes, and cereals.
- Deficiency infrequently seen in humans; when seen can show indications of mouth, oesophageal cancer and physical defects, and mental retardation.
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