9. MINERALS Flashcards
This module covers: • The essential minerals and how the body uses them. • The key food sources for each mineral. • How each mineral is absorbed and metabolised. • Potential interactions with other nutrients and drugs. • Signs and symptoms of deficiency and toxicity states. • Specific therapeutic considerations.
Define minerals
Minerals are inorganic elements that originate in the Earth that cannot be made by living organisms.
Where do most of the minerals in our diet come from?
Directly from plants (or indirectly from animal sources).
How are minerals absorbed and utilised in the human body?
Minerals are absorbed in the GIT (mostly in the small intestine) in their ionic state (with the exception of iron) and must be unbound from the organic compound with the help of digestive secretions (e.g., stomach acid) before being utilised by the body.
What affects the mineral levels in plants?
It vary depending on the mineral content in soil.
Minerals are found in all body tissues. Which two minerals make up the majority (approx. 75%) of the body’s total mineral content?
Calcium and phosphorus
Name 5 macro-minerals
- Calcium (Ca)
- Phosphorus (P)
- Sulphur (S)
- Magnesium (Mg)
- Potassium (K)
- Sodium (Na)
- Chloride (Cl)
List 5 trace-minerals
- Iron (Fe)
- zinc (Zn)
- iodine (I)
- Selenium (Se)
- manganese (Mn)
- Molybdenum (Mo)
- Copper (Cu)
- Chromium (Cr)
- Boron (B)
- Fluoride (F)
- Silicon (Si)
In which state do macro-minerals exist in the body (and in food)?
Mainly in the ionic state (as cations or anions)
List 5 key functions of minerals
- Building tissues; e.g., skeletal system, teeth.
- Nerve and muscle function.
- Thyroid health (supporting metabolism).
- Supporting immune health.
- Components of enzymes
Name 2 elements each which are Cations and Anions respectively?
Cations:
K+ (potassium), Mg2+ (magnesium), Ca2+ (calcium), Na+ (sodium)
Anions:
Cl- (chlorine as chloride); S- (sulphur as sulphate); P- (phosphorus as phosphate)
Which factors can affect mineral bioavailability?
1.In mineral deficiency states, the body upregulates absorption of the mineral. In excess states, it downregulates absorption.
- Food can enhance (e.g. ascorbic acid and Fe) or inhibit (e.g. phytates and Fe) absorption.
- Other minerals present in food (or supplements) — can compete for absorption: (e.g. iron supplements reduce Zn absorption; Zn antagonises Cu absorption)
In supplements, minerals are rarely found in their pure form. What are the carrier molecules called and name two organic and two inorganic forms
Carrier molecules called Ligands
Organic: Citrate, ascorbate, gluconate, glycinate.
Inorganic: Oxide, carbonate, sulphide, chloride.
What are three challenges with mineral supplementation?
Tolerability, bioavailability and chemical reactivity.
What is the most abundant mineral in the body and where is it mainly found?
- Calcium (Ca) is the most abundant mineral in the body accounting for 2% of body weight and 39% of the body’s mineral content.
- 99% of Ca in the body is found in mineralised connective tissues (bones and teeth).
- The rest (1%) is found in extra-cellular fluid, muscle and other tissues.
How are blood calcium levels regulated?
Ca levels in blood are tightly regulated by parathyroid hormone (PTH), vitamin D and calcitonin (at the expense of the skeleton when dietary intake is inadequate).
Which source of calcium is the most bio-available:
a) Full fat cow’s milk
b) Kale
b) Kale. Vegetable sources have the highest bioavailability, e.g., Ca from cruciferous vegetables is absorbed 2x as efficiently as Ca from dairy.
Name three foods that are good sources of Calcium
- Sage
- Sesame seeds
- Kale
- Sardines (incl. bones)
- Edamame beans
- Almonds
- Haricot beans
- Dairy foods such as cow’s milk
Name 5 functions of Calcium in the body
- Bone health
- Cell signalling
- Muscle contraction
- Blood clotting
- Neuro-transmitters
Why would you consider the therapeutical use of Calcium in the following:
a) Mood-related PMS symptoms
b) Muscle cramps
c) Osteoporosis
a) Ca is required for the conversion of tryptophan to serotonin (it is a co-factor).
b) Ca mediates vasoconstriction (from increased concentration of Ca2+ ions in vascular smooth muscle cells).
c) Ca is crucial for building and preserving bone mass; it is an abundant mineral that binds to the collagen framework in bone, increasing its density.
Where does the highest absorption of Ca occur, and why?
Ca is absorbed by all parts of the small intestine, but especially in the duodenum, where conditions are more acidic (due to the chyme that enters from the stomach), which increases absorption.
Explain the difference between how Ca is absorbed:
a) actively
b) passively
a) Active absorption is controlled by vitamin D
(calcitriol), which binds to the enterocyte vitamin
D receptor (VDR) and increases the transcription
of calcium transporters called calbindins, which increase calcium movement from the GIT to the blood.
b) Passive absorption occurs without vit. D, when Ca is consumed.
Which factors can affect mineral bioavailability?
- Mineral status in the body — in mineral deficiency states, the body upregulates absorption of the mineral. In excess states, it downregulates absorption.
- Substances present in food — can enhance (e.g., ascorbic acid and Fe) or inhibit (e.g., phytates and Fe) absorption.
- Other minerals present in food (or supplements) — can compete for absorption: (e.g., iron supplements reduce Zn absorption; Zn antagonises Cu absorption)”
Which factors that inhibit absorption of Ca and which factors that increase excretion?
Factors that inhibit absorption:
*Low vitamin D status
*Low stomach acid (HCl dissolves calcium salts)
*High intake of phytates / oxalates
*Gastrointestinal dysfunction
*Other minerals (e.g., Mg, Fe, Zn)
Factors that increase excretion:
*Menopause (low oestrogen)
*High animal-protein diets (due to high levels of urea and sulphuric acid)
*High-salt diets
*High caffeine intake
*Medications (see drug interactions)
Is loss of bone mineral density a asymptomatic or symptomatic condition?
Asymptomatic
What is likely the problem with high cow’s milk dairy consumption and osteoporosis risk?
The protein component of cow’s milk is likely the problem, as dairy is high in sulphur-based amino acids (e.g., methionine), which can increase sulphuric acid formation — leaching calcium (an alkaline mineral) from bones.
What are the risks of taking Ca?
*Kidney stones
*Soft tissue calcification, especially when vitamin D and K levels are inadequate
Studies mostly show that calcium supplementation is ineffective at preserving bone density when dietary intake is sufficient.
Which minerals Ca interfere with?
Mg, Fe, Zn, P
How much magnesium is in the human body, and where is it mainly found?
The body contains approx. 25g of Mg
60% in bone;
39% in cells and muscle;
1% in serum / extracellular fluid
What are the core elements in haemoglobin and chlorophyll, and how are their structures similar?
Haemoglobin and chlorophyll are almost identical in their structure.
Haemoglobin having iron at its core, and
chlorophyll (the green plant pigment), magnesium
Name three foods that are good sources of Magnesium
*Swiss chard
*Amaranth
*Pumpkin seeds
*Soy beans
*Cacao powder
Name 5 functions of Magnesium in the body
- Energy production
- Cell signalling
- Blood clotting
- Muscle relaxation
- Sleep and calming
How is magnesium absorbed and excreted in the body
*30–50% of dietary magnesium is absorbed, mostly in the distal small intestine (ileum)
*Phosphate and calcium can inhibit magnesium absorption
*Magnesium is excreted in urine, feces, and to a lesser extent during exercise and sweating
*Kidneys primarily regulate magnesium homeostasis
Why do serum magnesium levels not accurately reflect magnesium status?
Due to 99% of magnesium residing inside our cells.
Why would you consider the therapeutical use of Magnesium in the following:
a. Fatigue
b. Insulin resistance — diabetes, PCOS
c. Stress / anxiety
a. Needed to convert ADP to ATP
b. Essential for glucose metabolism
and insulin sensitivity (Mg is a co- factor, modulating glucose transport — needed for the activity of tyrosine kinase
b. Mg is used as a co-factor for GABA synthesis
What is ‘tolerable upper limit’ (TUL) for Mg supplementation
400 mg
Who should be cautious using high dose of Mg?
Someone with hypotension
Which form of Mg has high bioavailability?
Mg glycinate, citrate and malate
What are the common causes of Mg insufficiency?
- Poor nutrition (high in processed foods, low in dark green vegetables,
- Chronic stress (increases Mg excretion)
- Alcoholism
- Other malabsorption conditions.
What are the symptoms of Mg insufficiency
- Fatigue and insomnia.
- Anxiety, depression, irritability, panic attacks.
- Muscle cramps / spasms / twitches.
- Headaches (e.g., tension-type and migraines).
- Palpitations
Give three examples of the functions of zinc as a co-factor in metalloenzymes. How do these enzymes contribute to different biological processes?
- Antioxidant activity (Superoxide dismutase -SOD),
- Alcohol breakdown (Alcohol dehydrogenase)
- Protein digestion (Carboxypeptidase)
- Other enzymes involved in haem synthesis, folate absorption and DNA / RNA synthesis.
Name three foods that are good sources of Zinc
- Oysters
- Sesame
- Rye flour
- Calf’s liver
- Chickpeas
Name five functions of Zinc in the body
- Reproduction
- Cell proliferation
- Endocrine
- Sensory function
- Immunity and antioxidant
- Digestion
Why would you consider the therapeutic use of Zinc in the following:
a) Thyroid health
b) Frequent infections
c) Weak digestion
a) Needed for T4 to T3 conversion
b) Increases phagocyte, natural killer cell, T- and B-cell activity
c) Zn is used for the production of HCl and the synthesis of pancreatic enzymes
What enhances and inhibits Zn absorption
- Protein generally enhances Zn absorption
- Phytates in plants inhibit absorption. (Phytate levels can be reduced by soaking, sprouting and fermenting).
- Excess Ca, Cu and non-haem Fe may also inhibit Zn absorption
The absorption of which mineral is antagonised by Zn supplementation?
Copper
List five signs and symptoms of Zn deficiency
- Poor sense of taste and smell.
- Recurrent infections, delayed wound healing.
- Skin disorders (e.g., acne), dandruff, white spots on fingernails.
- Infertility (male and female) and low libido.
- Signs of weak digestion (e.g., bloating, fatigue).
When using Zn supplements, which form is well-absorbed?
Zn picolinate
Zn citrate
Zn acetate
Zn glycinate
What is Tolerable Upper Limit (TUL) for Zn
40 mg