Micronutrients and Bone Health

Minerals

Minerals are one of the six major nutrient classes.
They are found on the periodic chart.
Essential minerals cannot be made by the body and must be obtained from food.
The majority of minerals come from the soil, either directly or through animals that eat plants.
Minerals are inorganic, meaning they do not contain two or more carbons (homogeneous atoms).
Major minerals are needed in amounts greater than 100 milligrams a day.
Trace minerals are needed in amounts less than 100 milligrams a day.
There are 16 minerals with specific functions in the body, but we will only touch on a few.
Calcium is the most abundant mineral in the body, primarily stored in bones and teeth.
Phosphorus is the next most abundant, also stored in bone structure.
Other minerals to be discussed include sodium, iron, and iodine.

A variety of foods provides a variety of micronutrients.
Plant-based diets, proteins, dairy, fruits, and vegetables all contribute minerals.
We're not going to discuss every mineral (e.g., magnesium, boron), but focus on others.
Minerals are important for:
- Transport within the body
- Energy production
- Structural components

Minerals come from plants and animals.
Minerals from animal sources are generally more bioavailable than from plants.
Plant foods contain substances like phytic acid, fiber, and oxalates that bind to minerals, reducing their bioavailability.
Hydrochloric acid (gastric acid) increases absorption and bioavailability of most minerals.

Roles vary widely: muscle contraction, nerve impulse conduction, fluid balance.
Cofactors: Minerals partner with a protein to perform a function (similar to how coenzymes, which are vitamins, partner with proteins).
Deficiencies: Still an issue in the U.S., potentially due to food processing or poor dietary choices.
Toxicities: More likely from supplementation than food sources; examples include iron and zinc.

Know the name, function(s), food source (if mentioned), deficiencies (if any), and toxicities of the minerals discussed.
Minerals to be covered: sodium, potassium, calcium, iron, zinc, iodine, and possibly fluoride.

Sodium and potassium oppose each other in function.
Sodium is extracellular (outside the cell), while potassium is intracellular (inside the cell).
Both play similar roles in muscle contraction and nerve impulse conduction.

Location: Extracellular (sodium) vs. intracellular (potassium).
Source: Sodium primarily from processed foods; potassium from minimally processed or unprocessed foods. Food processing typically increases sodium and reduces potassium content.
Blood Pressure: Sodium elevates blood pressure in about 25% of the population (sodium-sensitive individuals), while potassium helps maintain healthy blood pressure in most individuals.

Plays similar roles to sodium and potassium in muscle contraction and nerve impulse conduction.
Component of hydrochloric acid in stomach acid, aiding in food breakdown and enzyme actions.

Calcium: Will be discussed in the context of bone health.
Iron: Discussion reserved for later.
Zinc: Important for the immune system and taste buds.
- Deficiency can lead to lack of appetite and decreased taste acuity.
- Excessive zinc (above 40-42 mg/day) can depress the immune system and taste acuity.
Iodine and Fluoride: Major details to be discussed later (or summarized briefly if not covered in detail).

Micronutrients (both vitamins and minerals) play various roles in metabolic processes.
Bone health involves multiple micronutrients, but focus will be on vitamin D and calcium.

Carbohydrates utilize B6; athletes may need more B6 to access glycogen stores.
Various micronutrients, mostly vitamins but also some minerals, enable the body to produce energy.

Cofactor: A mineral that partners with an enzyme (protein) to create a process.
B vitamins act as coenzymes.
Flavin adenine dinucleotide and nicotinamide adenine dinucleotide play a role in energy metabolism.

Obtained from food or synthesized in the skin from cholesterol upon exposure to sunlight.
Dietary sources of vitamin D are not very available.
Vitamin D synthesis from sunlight has decreased due to more time being spent indoors, making dietary intake or supplementation more important.
Made from cholesterol when the sun hits our skin.
Requires two activations: first in the liver (intermediate activation), then in the kidneys (final activation).
Dietary sources include fish oil and fortified products like milk.

Major component of bone structure; essential for bone development and maintenance.
Plays a role in the clotting cascade, nerve impulses, and muscle contractions.
99% of calcium is stored in bones and teeth, leaving 1% available in body fluids for critical functions.
The body manages the 1% of calcium in the blood through hormones:
- Calcitonin: Released when calcium levels are high; slows calcium release from bones and increases calcium excretion.
- Parathyroid Hormone: Released when calcium levels are low; causes the release of calcium from bones into the bloodstream.

Rickets: Occurs in children due to softening of bones; causes bowing of the legs.
Osteomalacia: Occurs in adults; bones soften due to lack of mineralization, leading to fractures.

No toxicity from sunlight exposure.
Excess vitamin D and calcium can lead to calcium deposition in soft tissues, muscles, arteries, and veins.

Different from osteomalacia.
Osteoporosis involves a decrease in bone mass, while osteomalacia is a lack of bone mineralization.
DEXA scan is used to measure bone density.

Weight-bearing activities (weight lifting, running) put stress on bones, promoting strength.
Nutrition: Adequate phosphorus, potassium, calcium, and vitamin D intake.
Smoking increases acidification, causing calcium to be removed from bones to neutralize the acid.
Medications can help maintain current bone density, but may not recover lost bone mass.