Minerals Notes

Classes of Nutrients

• Macronutrients:

  • Water

  • Carbohydrates

  • Proteins

  • Fats

• Micronutrients:

  • Vitamins

  • Minerals

Minerals

• Essential non-caloric inorganic nutrients needed in tiny amounts.

• Not destroyed by heat or light.

• Not changed during digestion.

• Mineral deficiencies are more critical than most vitamin deficiencies.

Function and Properties of Minerals

• Function: Necessary for normal structure (bone) and biochemical reactions (catalytic activity of enzymes).

• Properties:

  • Inorganic

  • Water-soluble

  • Absorbed directly into the blood

• Classification:

  • Major minerals (required more than 100mg/day)

  • Trace minerals (required less than 100mg/day)

Major Minerals

• Generally required in amounts larger than 100mg/day and stored in quantities greater than 5g.

  • Calcium

  • Magnesium

  • Sodium

  • Potassium

  • Chloride

  • Phosphorus

Calcium

• Principal divalent cation in the human body.

• Provides hardness and strength of bones and teeth.

• Salts of calcium are responsible for the rigidity of bone and teeth.

• More than 99% of calcium is in the bones and teeth.

• 1% in plasma, extracellular fluid, tissues, and calcium storage vesicles.

• Involved in the signal transduction pathway.

• Essential for:

  • Bone matrix formation (Hydroxyapatite)

  • Nerve function (Neurotransmitter release)

  • Muscle contraction

  • Blood clotting (essential for fibrin formation)

  • Cellular metabolism (binds to calmodulin)

Regulation of Blood Calcium

• Low serum calcium ($\downarrow$ Ca) stimulates parathyroid cell to secrete PTH ($\uparrow$ PTH), which restores serum calcium ($\uparrow$ Ca) by activating the parathyroid receptor (PTHR) in kidneys and bones.

Sources of Calcium

• Milk, cheese, and other dairy foods.

• Green leafy vegetables (broccoli, cabbage, okra, but not spinach).

• Soya beans.

• Tofu.

• Soya drinks with added calcium.

• Nuts.

• Bread and anything made with fortified flour.

• Fish where we eat the bones (sardines and pilchards).

Calcium - Recommended Daily Allowance (RDA)

• 0-6 months: 210mg/day

• Adults over 50 years: 1200mg/day

• Overdose Symptoms (3000mg per day or more):

  • Dehydration, diarrhea, lethargy, nausea, stomach pain, and vomiting.

• Deficiency Symptoms:

  • Muscle weakness, cramps, or even spasms and osteoporosis.

Magnesium

• Essential for more than 300 cellular metabolic reactions.

• Fourth most abundant cation in the body; most abundant (50-60%) in the bone.

• Mg2+ ion is associated with energy metabolism (ATP must form a complex with the Mg2+ before any catalytic reaction takes place).

• Important for protein formation, DNA production, and nerve conduction.

• Important in bone formation.

• Normally conserved by the kidneys and intestinal mechanisms, allowing blood levels to remain stable through a wide range of dietary intakes.

• Assists in calcium uptake but also competes with dietary calcium for the same absorption site in the intestine.

Magnesium - Sources and Deficiency

• Sources:

  • Green leafy vegetables

  • Spices

  • Nuts

  • Cereals

  • Coffee

  • Cocoa

  • Tea

• Deficiency:

  • Asthma

  • Diabetes

  • Osteoporosis

Magnesium - Importance and RDA

• Important as:

  • Element in every cell of the body

  • Hydroxyapatite (bone)

• Recommended Daily Allowance (RDA):

  • Children aged 0-6 months: 30mg/day

  • Adults from 31 years of age: 420mg for men, 320mg for women, and 360mg/day for pregnant women.

Electrolytes

• Mineral ions that make the largest contribution to the electrical charge of cells.

• Help regulate:

  • Fluid balance (osmolality and ionic strength)

  • Nerve response

  • Muscle contraction

Major Electrolytes

• Sodium (Na):

  • Extracellular and important in the control of blood pressure.

• Potassium (K):

  • Intracellular and less abundant than Na in the normal diet.

• Chloride (Cl):

  • Extracellular

• Phosphorus (P):

  • Intracellular

Sodium

• Roles in the body:

  • Solubility of minerals in the blood

  • Flexibility of the joints

  • Blood volume

  • Controls the body's acidity

  • Muscle contractions and nerve transmissions

• Sources:

  • Milk

  • Beets

  • Celery

  • Drinking water

  • Table salt

Sodium - Overdose, Deficiency, and RDA

• Overdose:

  • High Blood pressure

• Deficiency:

  • Low blood pressure

  • Swelling of brain cells causing headache, confusion, seizures, or coma.

• Recommended Daily Allowance (RDA):

  • Healthy adults: 2,300mg/day

  • 1,500 mg/day for people suffering from high blood pressure

Chloride

• Functions:

  • Keeps the amount of fluid within and around cells in balance

  • Helps regulate the pH (acid-alkali/acid-base) balance of body fluids

  • Maintains proper blood volume and pressure

  • Critical constituent of hydrochloric acid in the stomach, vital for maintaining the normal acidic environment needed by pepsin, and aids digestion and absorption of many nutrients including iron and vitamin B12

  • May help conserve potassium

Chloride - Overdose and Deficiency

• Overdose:

  • High blood pressure

• Deficiency:

  • Due to excessive sweating, diarrhea, or vomiting

  • Loss of appetite

  • Muscle weakness

  • Lethargy

  • Dehydration

Chloride - Sources and RDA

• Sources:

  • Table salt or sea salt as sodium chloride

  • Vegetables: seaweed, rye, tomatoes, lettuce, celery, olives

• Recommended Daily Allowance (RDA):

  • Adults: 3,400 mg/day

Potassium

• Major cation inside the animal cells.

• Maintains fluid and electrolyte balance in the body.

• Supports nerve transmissions.

• Promotes muscle growth.

• Regulates blood pressure.

• Sources:

  • Most fruits (parsley, dried apricots, bananas), vegetables, meat, and fish.

  • Dried milk, chocolate, almonds, pistachios, potatoes, bamboo shoots, avocados, soybeans, and bran.

Potassium - Deficiency and RDA

• Deficiency:

  • Muscle weakness

  • Decreased reflex response

  • In severe cases: respiratory paralysis, alkalosis, cardiac arrhythmia

• Recommended Daily Allowance (RDA):

  • Children 0-6 months: 400mg/day

  • Adults over 19 years of age: 4.7g/day

Phosphorus

• Main function: work with calcium and support the growth of strong, healthy bones and teeth.

• Also:

  • Helps activate the B complex vitamins

  • Assists in the synthesis of healthy cell membranes

  • Helps synthesis of DNA and RNA

  • Activates and deactivates enzymes through a process called phosphorylation

  • Supports proper kidney function

• Deficiency is very rare.

• Overdose: may cause severe nerve muscle spasms and convulsions.

Minerals for Maintaining Fluid Balance

• Sodium in the body helps regulate water in fluid compartments by being part of the Na/K "pump".

• Sodium helps keep the correct amount of water outside cells.

• Potassium helps keep the correct amount of water inside cells.

Trace Elements

• Zinc, Iron, Copper, Iodine, Manganese, Fluoride, Selenium

• Required in very very small amounts.

• Crucial to many body functions, including metabolic pathways.

Zinc

• Component of more than 100 enzymes which carry out a wide range of cellular functions.

• Most of the zinc is present in the muscle.

• Sources:

  • Red meat

  • Shellfish

  • Whole grain cereals

• Deficiency:

  • Slow wound healing

  • Decreased appetite

  • Loss of taste and smell

  • Decreased immune function

Functions of Zinc

• Cell replication

• Fertility and reproduction

• Hormone activity

• Cell growth

• Sexual maturation

• Gene expression

• Night vision

• Protein metabolism

• Immune function

• Lipid metabolism

• Hemoglobin activity

Iron

• Required in many metabolic reactions including energy production and oxygen transport (Hemoglobin and Myoglobin).

• Exists in two oxidation states: ferrous ($Fe^{2+}$) and ferric ($Fe^{3+}$)

• Required for the biosynthesis of heme and other non-heme iron containing proteins.

• Ionic forms of iron participate in several enzymatic reactions as non-heme irons, which are present as iron-sulfur clusters.

• Transportable and storage forms are bound to proteins.

• Only trace amounts of free iron exist under normal physiological conditions.

• Excess of free iron can cause tissue damage.

Iron Sources

• Foods of plant origin (non-heme)

• Foods of animal origin (hemoglobin, heme iron)

• As part of cytochromes, iron (Fe) is a coenzyme involved in energy metabolism.

Copper

• Component of many enzymes (amine oxidase, lysyl oxidase, ferroxidase, cytochrome oxidase, dopamine β-hydroxylase, superoxide dismutase, and tyrosinase).

• $Cu^{2+}$ ion plays an important role in collagen formation.

• $Cu^{2+}$ ions concentration, in the intra- and extracellular compartments, is maintained at very low levels by binding to the protein metallothionine.

• $Cu^{2+}$, together with iron, is necessary for hematopoiesis (ferroxidase).

Copper - Sources and Deficiency

• Sources:

  • Organ meats, shellfish, nuts, seeds, legumes, whole grains, potatoes, chocolate, and some fruits. Copper pipes may also add trace amounts of the metal to drinking water.

• Deficiency:

  • Defects in the formation of connective tissue (cardiovascular problems, poor bone formation).

Ultratrace Minerals

• Are required below 1mg/day

  • Boron

  • Chromium

  • Fluoride

  • Iodine

  • Molybdenum

  • Nickel

  • Selenium

  • Cobalt

  • Manganese

Iodine

• Function: essential components of two thyroid hormones: triiodothyronine (T3) and Thyroxine (T4).

• Thyroid hormones control the regulation of body temperature, basal metabolic rate, reproduction and growth.

• Source: Seafoods such as saltwater fishes are rich in iodine. Iodized salt.

• Iodine deficiency: Iodine deficiency is linked to goiter.

Selenium

• Present in humans as selenocysteine.

• Selenocysteine present in: glutathione peroxidase, iodothyronine deiodinase, and thioredoxin reductase.

• Antioxidant and enhances liver functions.

• Sources: Meat, seafood, and cereals.

• Deficiency:

  • Experimental animals: liver necrosis

  • Humans: heart problem, muscle dystrophy, muscle weakness