Calcium: Sources, Functions, and Daily Intake

Potassium Overview

• Potassium's symbol is K from the word "Kalium"
• Potassium is found in plant-based foods
• It is the most abundant cation inside the cell
• Potassium is one of the ions that can most easily enter and exit cells through K channels.
• Enters cells via the Na-K ATPase pump
• 98% is found in the intracellular fluid and 2% in the extracellular fluid
• An average daily intake of 40-200 nmol is provided from vegetables and fruits.
• About 90% of potassium is excreted by the kidney, and 10% from the GI tract
• Kidneys are the main excretory organ
• The renal distal tubule is the site of regulation
• Anti Diuretic Hormone (ADH) is the main regulatory hormone
• Normal serum value is 3.5-5.0 nmol/L

Factors Affecting Potassium Distribution

• Na-K pump
• Acid-base balance
• Cell destruction rate
• Plasma osmolarity
• Hormones: insulin, aldosterone, catecholamines

Na-K Pump

• Crucial transport mechanism in the cell membrane that maintains electrochemical balance
• Uses ATP to transport potassium (K+) into the cell and expels sodium (Na+) out of the cell.
• Vital for nerve transmission, muscle contraction, and cellular osmotic balance

Acid-Base Balance

• Plays a significant role in maintaining the body's acid-base balance.
• With a pH of 7 being neutral, pH<7 is acidic, and pH>7 is basic/alkaline:
• Low pH (acidosis) triggers cells to release K+ ions into the extracellular space in exchange for H+ ions
• High pH (alkalosis) triggers the opposite reaction, causing fluctuations in blood potassium levels

Cell Breakdown

• Cell destruction increases due to tissue damage, rhabdomyolysis, hemolysis, or tumor lysis syndrome.
• Intracellular potassium is rapidly released into the bloodstream, increasing the odds of hyperkalemia.
• High potassium levels that can have serious effects on heart rhythm

Plasma Osmolality

• This is the concentration of dissolved substances in the blood linked to potassium’s intracellular-extracellular balance
• Osmolarity is the number of osmotic active particles in one liter of solution
• Osmolality is the number of osmotic active particles in one kilogram of solution
• Increased osmolality triggers water to move out of cells, and intracellular potassium shifts into the plasma
• This leads to hyperkalemia.
• Osmolality increases due to hyperglycemia, dehydration, and osmotic shift

Hormones

• Insulin: Promotes potassium uptake into cells; lack of insulin can lead to hyperkalemia.
• Aldosterone: Increases potassium excretion through the kidneys while promoting sodium retention; high levels can cause hypokalemia.
• Catecholamines (Adrenaline, Noradrenaline): Stimulate the Na-K pump via beta-adrenergic receptors, increasing potassium entry into cells.

Use of Potassium in the Kidney Factors

• Aldosterone
• Amount of intracellular potassium
• Rate of excretion in urine
• Distal distribution of sodium
• Acid-base balance

Potassium Homeostasis Disorders

• Hyperkalemia: SERUM POTASSIUM >5.5 mmol/L
• Hypokalemia: SERUM POTASSIUM <3.5mmol/L

Calcium Overview (Existing)

• Calcium (Ca+2) is the most abundant mineral in the body
• It is sourced from both animal and plant based foods

Main Calcium Sources (Existing)

• Milk and milk products
• Green leafy vegetables
• Salmon and sardine fish, specifically with bones

Functions of Calcium (Existing)

• Plays a key role in tooth and bone health
• Activates several enzymes like lipase, ATPase, and succinate dehydrogenase
• Important for blood clotting
• Facilitates muscle contraction
• Maintains membrane permeability
• Supports nerve conduction

Calcium Levels (Existing)

• Bone mineral density is maintained by calcium
• 24-hour urinary calcium excretion exists
• Plasma total Calcium concentration: 2.15-2.57 mmol/L or 8.6-10.3 mg/dL

Recommended Daily Intake (Existing)

• The amounts are based on Recommended Dietary Allowances (RDAs) and Upper Levels (ULs)
• Ages 1-3: 700 mg/day for both males and females
• Ages 4-8: 1,000 mg/day for both males and females
• Ages 9-13: 1,300 mg/day for both males and females
• Ages 14-18: 1,300 mg/day for both males and females
• Ages 19-50: 1,000 mg/day for both males and females, UL is 2,500 mg/day for both
• Ages 51-70: 1,000 mg/day for males, 1,200 mg/day for females, UL is 2,000 mg/day for both
• Ages 71+: 1,200 mg/day for both males and females

Food Sources (Existing)

• Milk and dairy products are the best sources
• Good sources include molasses, oilseeds, green leafy vegetables, legumes, and dried fruits
• Moderate sources include green vegetables, eggs, and certain fruits
• Poor sources include grains, other vegetables and fruits, meat, fish, and chicken
• Consuming eggshells presents a risk of salmonella

Calcium Content in Foods (Existing)

Best Sources (Existing)

• Foods include skimmed cow's milk (123 mg/100g), semi-skimmed cow's milk (122 mg/100g), whole cow's milk (119 mg/100g)
• Other foods are low-fat yogurt (120 mg/100g), full-fat yogurt (111 mg/100g), fat-free white cheese (96 mg/100g)
• Further foods include full-fat white cheese (162 mg/100g), Edirne white cheese (437 mg/100g), Urfa white cheese (338 mg/100g), plain cream cheese (80 mg/100g)
• Kars-type cheese (731 mg/100g), cheddar (721 mg/100g), aged Kashar cheese (700 mg/100g)
• Roquefort cheese (662 mg/100g), dried curd cheese (505 mg/100g), Herb cheese (497 mg/100g)

Good Sources (Existing)

• Foods include grape molasses (400 mg/100g), almonds (234 mg/100g), hazelnuts (209 mg/100g)
• Further foods are pistachios (131 mg/100g), sunflower seeds (120 mg/100g), sesame (110 mg/100g), walnuts (99 mg/100g), roasted peanuts (72 mg/100g)
• More foods include soybeans (226 mg/100g), chickpeas (150 mg/100g), white dry beans (144 mg/100g), hyacinth beans (135 mg/100g), broad beans (102 mg/100g)
• Lentils (79 mg/100g), black-eyed peas (74 mg/100g), dried okra (678 mg/100g), dried beans (480 mg/100g), dried eggplant (137 mg/100g)
• Dried pepper (120 mg/100g), vine leaves (392 mg/100g), arugula (205 mg/100g), fresh parsley (203 mg/100g), fresh mint (200 mg/100g)
• Additional foods include madimak (166 mg/100g), beet leaves (119 mg/100g), black cabbage (116 mg/100g), swiss chard (114 mg/100g)
• Spinach (93 mg/100g), fresh okra (92 mg/100g), curly lettuce (81 mg/100g), leek (52 mg/100g), green onion (51 mg/100g)
• Kiwi (100 mg/100g), dried plum (90 mg/100g), dried apricot paste (86 mg/100g), dried fig (126 mg/100g), dried bean curd (67 mg/100g)
• Dried grape (62 mg/100g), dried mulberry (51 mg/100g), tarhana (fermented soup) (685 mg/100g)

Moderately Rich (Existing)

• Foods include eggs (56 mg/100g), oranges (41 mg/100g), mandarin (40 mg/100g), grapefruit (36 mg/100g), fresh fig (36 mg/100g)
• Other foods include blackberry (32 mg/100g), cherry-sour cherry (22 mg/100g), strawberry (21 mg/100g), white cabbage (49 mg/100g), Brussel sprouts (47 mg/100g)
• Further foods include fresh fava beans (43 mg/100g), celery (43 mg/100g), fresh red pepper (29 mg/100g), garlic (29 mg/100g), summer squash (28 mg/100g)
• Fresh black-eyed peas (27 mg/100g), dried onion (27 mg/100g), peas (shelled) (26 mg/100g), cucumber (unpeeled) (25 mg/100g)
• Asparagus (22 mg/100g), winter squash (21 mg/100g), cauliflower (25 mg/100g), cucumber (peeled) (17 mg/100g)
• Ed Cabbage (42 mg/100g)

Weak Sources (Existing)

• Foods include beef (11 mg/100g), veal (11 mg/100g), lamb (10 mg/100g), turkey (meat & skin) (15 mg/100g)
• Whole chicken (meat & skin) (11 mg/100g), sea bass (21 mg/100g), swordfish (17 mg/100g), sturgeon (12 mg/100g), mackerel (8 mg/100g)
• Other foods include bread (wheat flour) (19 mg/100g), flatbread (57 mg/100g), lavash bread (45 mg/100g), bulgur (36 mg/100g), semolina (25 mg/100g)
• Popped corn (10 mg/100g), phyllo dough (7 mg/100g), red plum (18 mg/100g), fresh apricot (16 mg/100g), melon (14 mg/100g)
• Additional foods are fresh damson plum (12 mg/100g), fresh grapes (12 mg/100g), quince (11 mg/100g), peach (9 mg/100g), pear (8 mg/100g)
• Banana (8 mg/100g), apple (7 mg/100g)

Special Cases for Calcium Intake (Existing)

• Consuming fish with bones provides calcium
• Calcium is released from bones into the water when boiled in an acidic environment.

Calcium Requirement - Excretion (Existing)

• Factors affecting the absorption rate and that increase urinary calcium excretion should be considered
• These factors include:
  • Excessive protein intake, sodium, alcohol, and caffeine, which increase urinary calcium excretion

Effects of other substances (Existing)

• One cup of instand coffee causes 6 mg of calcium excretion
• 1 gram of extra protein causes 1.75 mg of calcium excretion
• Doubling protein intake can increases urinary calcium excretion by 50%
• Daily sodium load of 2.3 grams increases urinary calcium excretion by 40 mg

Calcium Absorption (Existing)

• Calcium in foods is bound to other elements
• Calcium must be released from these complexes and converted into a soluble form for absorption
• Gastric secretions enhance the solubility of calcium complexes
• Calcium binds to calcium-binding protein (CaBP) in the duodenum and is absorbed through active transport
• High calcium concentrations in the small intestine causes absorption, which occurs through diffusion.
• Several factors influence calcium absorption in the small intestine, and these factors can have positive or negative effects.

Calcium Metabolism (Existing)

• Of the dietary calcium intake (1000mg), 70-90% is not absorbed, and 10-30% of calcium is absorbed
• Factors which effect if Calcium is absorbed include
  • High phosphorus, fat, oxalic and phytic acid, low vitamin D, and high pH reduces absorption, leading to excretion with feces.
  • Increased growth/development requirement, vitamin D, low pH, and lactose increases absorption, leading to excretion with urine.

Factors that Increase Absorption (Existing)

• A high need for calcium, such as growth, pregnancy, or breastfeeding
• Greater calcium absorption exists in newborns and children (approximately 60%)
• Absorption is higher in pregnant women(50%)
• The presence of lactose, which is from milk, increases absorption
• Vitamin D further stimulates calcium-binding protein synthesis and thus calcium absorption
• The natural sugar of milk composition is lactose, resulting in more lactose and vitamin D which raises the absorption rate of calcium.
• Calcium in milk absorbs more effectively than the calcium from other plant-based foods.
• It converts into lactic acid by bacteria in the small intestines, lowering the pH of the environment.
• An acidic environment, created by protein and some amino acids in the upper part of the small intestines
• Vitamin C, citric acid, and bile acids

Factors that Reduce Absorption (Existing)

• Excessive phosphorus Intake, optimal Calcium to Phosphorus ratio in the diet
• Children(1.5 - 1.0 Ca/P)
• Adults(1.0 Ca/P)
• Excessive fiber intake
• Higher fiber makes bound with Ca and prevents absorption
• If either calcium or phosphorus is taken in excess, then less of both minerals increases.
• The excretion of the less consumed mineral increases.
• High Fat
• Too much dietary fat reduces absorption
• Alkaline environment
• Digestion and Absorption Problems
• Excess Zinc and Aluminum Intake
• Alcohol Consumption

Oxalic and Phytic Acid (Existing)

• Oxalic acid is in green leafy vegetables
• Phytic acid is in grains, especially in the outer layer of wheat
• Fiber, oxalic acid, and phytic acid reduce calcium absorption.
• Excessive fiber makes bound with calcium and prevents its absorption.
• Amount of oxalic acid in green leafy vegetables can vary however some leafy greens are good sources
• Some compounds bind to iron forming insoluble complexes that reduce calcium absorption.

Those with low calcium absorption (Existing)

• Elderly people
• Postmenopausal women
• Decrease in vitamin D uptake and activation
• Estrogen hormone deficiency
• Decreased stomach acid secretion

Calcium Supplementation (Existing)

• Should be taken with meals
• A single dose should not exceed 500 mg for optimal absorption

Calcium and Mortality (Existing)

• A prospective study on calcium supplementation and mortality examined the relationship between calcium supplements and mortality of cancer types
• Daily calcium supplement < 1000 mg in men show no association with mortality
• Use of calcium supplements of 1000 mg or more indicate a high risk for all causes of mortality
• Calcium intake has been found to be inversely related to mortality when concerning women with calcium taken at: <500mg; 500-1000mg; >1000mg

Calcium Absorption (Processes) (Existing)

• Simple Diffusion: Calcium absorption rate depends on calcium concentration in the intestinal lumen
• Active Transport: Requires energy and carrier molecules which regulates the transport of vitamin D

Hormonal Control of Calcium Levels (Existing)

• Regulated by parathyroid hormone (PTH), calcitonin, & vitamin D (calcitriol)
• These affect 3 main organs: bones, small intestines & kidneys.

When Serum Calcium Levels Drop (Existing)

• The parathyroid gland stimulates which triggers the secretion of parathyroid hormone (PTH)
  • PTH allows calcium to pass from bone to blood.
  • Increases calcium reabsorption from the kidneys and reduces its excretion
  • Increases calcium absorption from the intestine by stimulating the conversion of vitamin D to calcitriol in the kidneys.
• This allows serum calcium levels to return to normal, and ensures the normal function of the body

When serum Calcium Levels Rise (Existing)

• When serum calcium level rises above normal limits, calcitonin is secreted by the stimulated thyroid gland
  • It ensures the deposition and storage of calcium from the serum into the bone
  • It reduces calcium reabsorption from the kidneys and increases calcium excretion in the urine.

Metabolic Functions of Calcium (Existing)

• Bone and tooth formation
• Blood clotting: prothrombin converts to thrombin via calcium
• Nerve conduction is important, and nerve impulses takes part in transportation.
• Enables muscle contraction, which free ionized calcium activates the chemical reaction between myosin and actin
• Controls fluid passage through membranes
• Is an important activator of some enzymes such as: ATPase, lipase and choline esterase

Symptoms when deficient (Existing)

• Tetany occurs with spastic muscle contractions and muscle pain which produces rotations and curls in the fingers
• Osteoporosis is caused by bone calcium loss and is specifically seen in post-menopausal women experiencing losses in calcium within 5 years after menopause

Further Loss of Calcium (Existing)

• 0.75 - 1.0% / per year occurs after age 35
• 2-3% / per year occurs, during the first 5 years after menopause
• 1% / per year occurs after 5 years where there is an average of 10% loss every 10 years

Protection from Calcium Loss (Existing)

• Consume adequate Calcium early on.
• Take Vitamin C, for it takes part in collagen synthesis
• Lack excessive protein, caffeine, salt as too much will increase the excretion of calcium
• Reduce your Stress due to it increasing the excretion of calcium

Further Treatments for Calcium Loss (Existing)

• Take actions such as movement and activity
• Vitamin D and hormone (estrogen) therapies
• Additional factors regarding the loss of calcium include:
• Parathyroid Overactivity
• Insufficient Dietary Calcium intake
• Early Menopause
• Inactivity / Excessive movement
• Genetic Predisposition and insufficiency of Vitamin D
• High Consumption of excessively Salty Foods, Excessive protein intake through diet, also taking Excessive Caffeine and/or Alcohol consumption
• Being More common for African and Asian, but more so Whites
• For men, this is more common later

Deficiencies Associated to Loss of Calcium (Existing)

• One includes Rickets and Osteomalacia
• The other is resportive Hypercalciuria- where Calcium is heavily removed from the bone, increasing urinary excretion

Lactose Intolerance and Calcium (Existing)

• Individuals that may not have the enzyme lactase, which is necessary to digest lactose, may need alternative methods of consumption.
• If not, then those people may experience stomach cramps, gas, and diarrhea.

Ways to gain Calcium while being Lactose Intolerent (Existing)

• To consume yogurt or cheese for the lower lactose intake
• To consume the dairy in low doses, or take lactose- reduced products

Obesity and Calcium (Existing)

• Obesity results in an inverse proportional relationship to those who take more BMI (Body Mass Intake)
• Factors include those who intakes of Dietary Calcium
• Or intakes through : Adipocytes, Thermogenesis and Fat Oxidation, Fecal Fat Excretion, Impact on Appetite Control, Insulin Resistance

Potassium rich foods

• Apricot (3 medium-sized): 281 mg
• Dried apricot (4 large): 490 mg
• Asparagus (6 spears): 278 mg
• Avocado (½ medium): 604 mg
• Banana (1 medium): 569 mg
• Coked white beans (½ cup): 416 mg
• Green beans (½ cup): 150 mg
• Broccoli (1 stalk): 267 mg
• Melon (1 slice): 251 mg
• Plum (2 small): 208 mg
• Grapefruit (½ medium): 166 mg
• Mushroom (4 medium): 414 mg
• Orange (1 medium): 237 mg
• Orange juice (1 cup): 496 mg
• Peach (½ medium): 202 mg
• Peanuts (1 handful): 494 mg
• Potato (1 half medium): 504 mg
• Spinach (8 large leaves): 490 mg
• Raisins (½ medium): 544 mg
• Cooked pumpkin (½ cup): 323 mg
• Cooked acorn squash (½ cup): 749 mg
• Sunflower seeds (½ cup): 920 mg
• Sweet potato (½ medium): 367 mg
• Tomato (1 medium): 244 mg
• Watermelon (1 slice): 600 mg