m9 - minerals

macrominerals versus microminerals

macro

 present in greater amounts in the body

 recommended intake ≥100 mg per day

 calcium, phosphorus, potassium, sulfur, sodium, chloride, magnesium

Micromineral (or trace minerals)

• recommended intake <100 mg per day

• iron, copper, manganese, iodine

what is calcium regulated by?

Blood levels of calcium regulated by:

 Vitamin D

 Parathyroid hormone

Calcium is constantly deposited into and released from bone

function of calcium

• muscle contraction and nerve transmission (regulates levels of Na+ and K+ ions)

• vit. C needed for collagen synthesis

• Calcium makes up the crystal in bone, hydroxyapatite, which provides bone strength

bone diseases

Osteopenia - weakening of bone density

• Osteoporosis – bones become porous

(loss of strength and density)

• Higher risk of fractures and breaks

osteoporosis prevention

 Balanced diet with adequate calcium and vitamin D

 Regular exercise (includes aerobic and strength)

 Avoid smoking

 Limit alcohol intake

calcium metabolism

Hormone regulation

• Hormone binds to cell surface receptor

  ￿Triggers release of calcium in cell

  ￿Calcium amplifies the hormone’s message

  ￿Thus, calcium is a second messenger

calcium blood clotting

Calcium is needed to convert prothrombin into thrombin

Thrombin is enzyme that converts fibrinogen into fibrin

calcium blood pressure

Calcium can have protective effect against hypertension

calcium regulation in blood

parathyroid hormone

• When blood calcium levels are low :

  •PTH release 

   Triggers conversion of vitamin D to active form,

  calcitriol

   Calcitriol  calcium absorption in intestine

   Calcitriol and PTH  calcium resorption in

  kidneys

   Calcitriol and PTH release calcium from bone

decrease in calcium dietary factors

Some plant-based foods contain a compound called:

•Phytates

•Bind certain minerals making them unavailable to cells:

 Calcium

 Zinc

 Iron

Another compound that binds minerals with positive charges:

•Oxalate

•Tea, chocolate

increase in calcium absorption

Presence of milk sugar, lactose, yogurt in gut

sardines, green leafy veggies

Increased physiological need for calcium

•periods of growth

•pregnancy

•lactation

calcium intake levels

RDA for adults ages 19 – 50 yrs.

•1,000 mg per day

RDA for females > age 50 yrs. and males > 70 yrs.

•1,200 mg per day

RDA for adolescents

•1,300 mg per day

food source calcium

Dairy products are the best calcium sources, but other

sources are available:

•Canned sardines and salmon with bones

•Turnip greens

•Broccoli

•Other green, leafy vegetables

•spinach is an exception

phosphorous function

• Part of bones and teeth

• Facilitates enzyme function

•Can also turn off function of enzymes

• Adenosine triphosphate (ATP) component

•“usable” form of energy

• DNA and RNA component

• Phospholipid component

•Part of cell membranes

•Lipoproteins

• Acid-base balance

•Phosphorus ions act as a buffer in blood

phosphorous food sources

• meat, fish and poultry

• eggs

• milk and milk products

• cereals and grains

• legumes

• Other sources: tea, coffee,

chocolate, and soft drinks

700 mg per day

magnesium function

Component of hydroxyapetite crystals in bone

•Bone serves as a store of magnesium

Maintenance of DNA and RNA integrity

•Works with phosphorus

ATP stabilization

Facilitates muscle contraction:

•Calcium – contraction

•Magnesium – relaxation

In the cell, magnesium is cofactor for almost 300 different enzym

magnesium requirements and food sources

 RDA:

•400 mg per day for men

•320 mg per day for women

•Most Americans consume below this amount

Food sources:

•Green leafy vegetables (spinach, collards, and turnip greens – the best!)

•Unpolished grains

•Nuts

•Legumes

•Whole-grains

chocoloate

primary storage of sulfur

in amino acids methionine and cysteine

 −Sulfur in cysteine can bond to another cysteine to

form a bridge or link

Sulfur is also a key element in glutathione

•A strong antioxidant in the body

sulfur dietary requirements and sources

Dietary sources of sulfur include protein-containing foods

B-vitamins biotin and thiamin contain some sulfur

In plant-based foods:

•Levels depend on sulfur content of soil

Sulfur added to foods as sulfites for preservation or flavoring

•breads and other baked goods

•dried foods

•canned or pickled foods

•condiments

•wine and beer

iron function

Storage in body

•Relatively small amount 2–4 g

•Importance of iron should not be underestimated

•iron deficiency is most common, widespread nutrient deficiency worldwide

•Primary Role:

•assist in delivery of O2 to tissues and cells iron found in center of hemoglobin molecule

oxygen delivery iron

Iron is found in hemoglobin of red blood cells

(RBCs)

•Delivers O2 to tissues and cells in body

 −Picks up CO2

Body’s bone marrow produces 2.5 million

RBCs per second

•Equivalent number of RBCs destroyed in

liver, spleen, and lymph nodes

anemia

•clinical condition in which hemoglobin level is too low

•iron-deficiency anemia is one form

 - caused by low iron stores or inability to use iron for hemoblogin synthesis

tests for anemia

Hemoglobin

• Hematocrit

 The percentage of blood that is composed of red blood cells

• Ferritin

 Storage protein for iron; first to respond to low iron stores

• Transferrin saturation

 Amount of iron transferrin is transporting in blood

causes of iron deficiency anemia

•Inadequate iron intake

•Inadequate iron absorption

•Copper deficiency

•Blood loss

Other causes of anemia:

•A deficiency of vitamin B6, vitamin B12, folate, or chronic disease

Heme Iron

 Form found in hemoglobin

 Only found in meats, fish, and poultry, shellfish (oysters)

 More readily absorbed in body

non-heme iron

 Elemental form of iron

 Found in plan-based and enriched foods

•  Beans

   Green, leafy vegetables

   Dried fruit

   Raisins, Apricots

   Enriched cereal

 Less readily absorbed in body

factors that increase iron absorption

Factors that enhance non-heme iron absorption:

•Vitamin C

•Presence of meat, poultry and fish in the diet

•phenomenon referred to as meat, fish, and poultry factor (MFP)

factors that decrease iron absorption

• Tannins (coffee, tea)

• Phytates (whole grains, seeds, nuts, and legumes)

iron requirements

8 mg/day – males and females over age 50

18 mg/day - women ages 19 to 50 yrs.

•Increased needs due to iron loss during menstruation

27 mg/day – pregnant women

what form of iron is most easily absorbed

heme iron

Identify individuals with increased iron requirements

• Infants and young children

• Menstruating individuals

• Pregnant individuals

• Lactating individuals

• Vegetarians and vegans

• Individuals with chronic blood loss or gastrointestinal conditions

• Athletes and regular endurance exercisers

iron toxicity

UL = 45 mg per day

Some individuals cannot regulate amount of iron absorbed → dangerous levels of iron build-up

Genetic disorder that can cause iron toxicity is:

•Hemochromatosis

Symptoms of iron toxicity:

•abdominal pain, fatigue, depression (in early stages)

•may advance to liver damage if iron build-up is not treated

zinc function

•Development of sexual organs and bone growth

•Alcohol metabolism

•Antioxidant enzyme function

•Blood pressure regulation

•Insulin release and function

•DNA replication

•Protein synthesis, growth and development

•Immune function

•Hemoglobin synthesis

signs of zinc deficiency

Dwarfism in young teens, particularly males

•Poor sexual development (underdeveloped testes in males)

•Deformed bones

•Abnormal hair and nails; loss of hair

•Poor wound healing

•Hypogeusia

•Gastrointestinal disturbances

•Impaired folate and vitamin A absorption

zinc absorption

40 % of dietary zinc is absorbed in small intestine

•Absorption depends on body’s needs

•When sufficient body stores exist, the small intestine makes protein to bind zinc and prevent

absorption

Zinc absorption when:

•Meat, fish, and poultry present in diet

zinc decreased absorption

Also found in legumes and whole-grain cereals

• absorption due to presence of phytates

zinc dietary sources

•meats

•poultry (turkey in particular)

•oysters

•herring

•eggs

zinc requirements

RDA

•11 mg per day for men

•8 mg per day for women

UL

•40 mg per day

•Consuming excess zinc may:

 Decrease HDL

 Increase risk of infections

copper function

Exerts physiological effects as a cofactor for enzymes

Needed for absorption, storage, and metabolism of iron

Functions of copper:

•Iron use and incorporation into hemoglobin and

RBCs

•Antioxidant defense against free radicals

•Strengthening collagen and, therefore, connective tissue

•Immune defense

•Synthesis of neurotransmitters

•Energy production via ATP synthesis

What other mineral may hinder copper absorption?

50% of dietary copper is absorbed

Location of absorption:

•Most absorption occurs in small intestine

Copper and zinc share a protein that regulates how much of each is absorbed, as a result:

•Excess zinc can interfere with copper absorption

copper requirements and sources

RDA: 900 μg per day for adult males and female

Few cases of copper deficiency reported

UL: 10 mg per day

•Vomiting and liver damage can occur when UL is exceeded

Good sources:

•Organ meats (ie.liver)

•Shellfish

•Chocolate

•Nuts

•Legumes

•Drinking water (especially if water runs through copper pipes)

iodine function

Facilitates production of a hormone in thyroid gland

 −Thyroid hormone, also called thyroxine

oControls basal metabolic rate

o Made from tyrosine and iodin

iodine deficiency

Lack of iodine in diet results in thyroid gland cells enlarging in attempt to absorb more iodine from blood

•an enlarged thyroid is referred to as: goiter

Iodine deficiency in pregnant women may cause:

•Offspring to be born with cretinism

 −Stunted height

 −Developmental delays

iodine requirements and sources

RDA: 150 μg per day

UL: 1,100 μg per day

•Excess intake can lead to enlarged thyroid gland

Food sources:

•Seafood

•Iodized salt

•Plants grown in areas with sufficient iodine in the soil are also good sources of iodine

What is the primary function of selenium in the human body?

•Supports body’s antioxidant defense system

•Part of the antioxidant enzyme, glutathione peroxidase

 − activity of enzyme depends on level of selenium present

What is the primary function of fluoride in the body?

strengthen tooth enamel and protect bones by promoting mineral deposition

Can an individual consume too much fluoride? If so, what condition may develop

yes; fluorosis