Unit 2.6A Controlled Mineral Diets PDF

Mineral restricted diets. Characteristics and implementation. Food sources. Dietary recommendations. 1 Unit 2.6 A Prepared by: Teresa Climent  MINERALS  Inorganic elements that are essential...

Mineral restricted diets. Characteristics and implementation. Food sources. Dietary recommendations. 1 Unit 2.6 A Prepared by: Teresa Climent  MINERALS  Inorganic elements that are essential to the nutrition of humans, animals and plants.  Represent approximately 4 to 5% of body weight.  Of this weight, 50% is calcium, 25% is phosphorus and the remaining 25% accounts for:  magnesium, sodium, potassium, chloride and sulphur (>100 mg/day) and  iron, zinc, iodide, selenium, manganese, fluoride, molybdenum, copper, chromium, cobalt and boron ( 5,0 mmol/L Hypokalaemia: [K+]Plasma < 3,5 mmol/L  Both may have serious consequences, such as abnormal heart rhythm or even cardiac arrest (when the heart stops).  The body can use the large reservoir of potassium stored in cells to help maintaining a constant level of potassium in the blood. 8 Foods: Potassium is widely available in many foods, especially fruits and vegetables (bananas, avocado and sweet potato) and protein-dense foods (meat, fish and eggs). Absorption: Absorbed by diffusion (especially in the colon). The same amount is eliminated, mostly in urine if kidneys are working properly. Daily requirements Healthy individuals 3,5-4,7 g K+ /day For renal patients, always less! Chronical renal failure with no hyperkalaemia: 1-1,5 g K+/day Hemodialysis: 2,3-2,7 g K+/day Peritoneal dialysis : 3 g K+ /day 9  Hyperkalaemia: [K+]Plasma > 5,0 mmol/L Aetiology: Use of the so called “K-sparing diuretics”. Drugs that contain it (for instance, KCl instead of NaCl). Acidosis (H+ exchange by intracellular K+). Excessive intake of fruits and vegetables. Renal failure requiring dialysis (see unit 2.4*). Symptoms: Muscle weakness or abdominal cramps Paraesthesia Irritability Diarrhoea Mental confusion Hypotension Arrhythmia *If renal K+ excretion decreases [GFR10 mL/min, diabetes,…], hyperkalemia may occur and cause heart rhythm disturbances 10  Hypokalaemia: [K+]Plasma < 3,5 mmol/L It’s one of the most common water-electrolyte imbalances. Aetiology: Vomiting or profuse diarrhoea. Use of diuretics. Corticosteroids or laxatives. Cushing’s disease: a disorder caused by the body’s exposure to an excess of the hormone cortisol. Symptoms: legs cramps, tiredness, hypotonicity, weakness, arrhythmias, constipation, cardiac arrest. Recommended diets: Eat foods rich in potassium. Use KCl instead of NaCl. Eat fresh food rather than boiled food: cooked foods have less K+ (it is soluble in the cooking water). Drink the vegetable cooking water. 11  CALCIUM AND PHOSPHORUS Calcium (Ca2+ or Ca++) and phosphorus (Pi) are essential elements, representing 99% and 85%, respectively, of the bone tissue, among other functions by themselves. Both together form hydroxyapatite, the main structural component in bones and tooth enamel. Requirements (variable needs depending on age, gender, illness): Ca2+: 400–1500 mg/day (0,4-1,5 g/day) Pi: 300–1200 mg/day (0,3-1,2 g/day) Hormone regulated by: Parathyroid hormone (PTH), calcitonin and vitamin D. 12  Recommended Dietary Allowances (RDAs) for Calcium 1300 mg for children aged 9 to 18. 1000 mg for adults aged 19 to 50. 1200 mg for women aged over 51 and for all adults over 70. Recommended Dietary Allowances (RDAs) for Phosphorus (see next slide*) Lower than that of calcium for all groups. 700 mg/day adults RDAs are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the National Academies of Sciences, Engineering, and Medicine 13  Recommended Dietary Allowances (RDAs) for Phosphorus Lower than that of calcium for all groups. 700 mg/day adults Table 1: Recommended Dietary Allowances (RDAs) for Phosphorus Age Male Female Pregnancy Lactation Birth to 6 100 mg 100 mg months* 7–12 months* 275 mg 275 mg 1–3 years 460 mg 460 mg 4–8 years 500 mg 500 mg 9–13 years 1,250 mg 1,250 mg 14–18 years 1,250 mg 1,250 mg 1,250 mg 1,250 mg 19+ years 700 mg 700 mg 700 mg 700 mg 14  CALCIUM o Helps bone structure to develop and grow during pregnancy, lactation, infancy, childhood and adolescence. o Helps postmenopausal women maintain bone health. o Involved in ions transition across the membranes of cell organelles. o Involved in nerve transmission and the regulation of heart muscle function. o Is a cofactor for several enzymatic reactions. 15  PHOSPHORUS o Contained in the deoxyribonucleic acid (DNA) and the ribonucleic acid (RNA). o Adenosine triphosphate (ATP), the major cellular form of energy, contains phosphate bonds. o Is a component of phospholipids in membrane cells. o Involved in the phosphate buffer system. 16  Regulation of serum calcium and phosphorus  Phosphorus and calcium are interrelated because hormones, such as vitamin D and parathyroid hormone (PTH), regulate the metabolism of both.  The amount of Ca2+ in bones is in equilibrium with Ca2+ in the blood.  When the concentration of blood calcium falls, PTH stimulates the transfer of exchangeable Ca2+ from the bone to the blood.  At the same time, PTH promotes renal tubular resorption of Ca2+ and indirectly leads to increase the intestinal absorption of Ca2+ by increasing the kidney’s production of vitamin D. 17 CALCIUM BALANCE 18 19  High-calcium diets (in hypocalcaemia) When: - Increased needs (growth, pregnancy, lactation, menopause, ageing). - Intestinal malabsorption. - Hypocalcaemia in low weight or preterm neonates. - Hyperphosphatemia (high phosphate reduce the Ca2+ concentrations). - Strict vegetarian diets. - Corticosteroids, antiacids, hypochlorhydria (gastrectomy, etc.). - Osteoporosis. - Hypertension: Ca2+ decreases blood pressure (see next slide*). - Colon cancer: diets rich in Ca2+ seem to offer protection against it. - Rickets and osteomalacia (defective bone growth, Vit. D, Ca2+ and P). Recommendations: Diet rich in dairy products and/or oral supplements of calcium (with meals). The Ca:P ratio should be 1-2:1 (see next slide**). Provide good exposure to sunlight. Avoid the ingestion of calcium with fat, phytates or oxalates (which reduce Ca2+ absorption). 20  High calcium diets - *Hypertension: Ca2+ decreases blood pressure (BP). Increases in calcium intake have been shown to lower BP in hypertensive and normotensive subjects. Dietary calcium interventions, such as supplementation or food fortification, were found to significantly reduce systolic blood pressure (SBP) and diastolic blood pressure (DBP) in normotensive subjects. A meta- analysis of prospective cohort studies revealed that higher calcium intake from food and supplements is associated with lower risk of hypertension. Calcium intake has been considered to have the effect of inhibiting the renin-angiotensin system and reducing the contractions of vascular smooth muscles cells. Although the hypotensive effects of dietary calcium intake are weak, small reductions in BP are considered to have important health implications for cardiovascular diseases. 1. Cormick G., Ciapponi A., Cafferata M.L., Belizán J.M. Calcium supplementation for prevention of primary hypertension. Cochrane Database Syst. Rev. 2015;30:CD010037. doi: 10.1002/14651858.CD010037.pub2. 2. Jayedi A., Zargar M.S. Dietary calcium intake and hypertension risk: Dose-response meta-analysis of prospective cohort studies. Eur. J. Clin. Nutr. 2018;10 doi: 10.1038/s41430-018-0275-y. 3. Zemel M.B. Calcium modulation of hypertension and obesity: Mechanisms and implications. J. Am. Coll. Nutr. 2001;20:428S–435S; discussion 440S–442S. doi: 10.1080/07315724.2001.10719180. 21 **The Ca:P ratio should be 1-2:1 22  Sources of calcium  Milk and other dairy products.  Green leafy vegetables such as curly kale, okra, spinach, broccoli, and collards.  Clams, oysters, kale, turnip greens, mustard greens, and tofu.  Bread and foods made with calcium-fortified flour.  Fish with eatable bones, such as sardines and pilchards.  Soybean.  Calcium-fortified foods.  Oxalates limit the availability of calcium in rhubarb, spinach, chard and beet greens. 23 24  Low-calcium diets (in hypercalcemia) In renal lithiasis, dietary treatment is effective if these recommendations are followed:  Increase the intake of liquids.  Limit the intake of proteins (it favours hypercalciuria).  Acidify the urine (increase the solubility of Ca2+).  Decrease the intake of salt NaCl (in Na-dependent calciuria).  Avoid:  overload of vitamin C (source of the endogenous oxalate)  oral supplements of calcium  more than one portion of dairy products/day 25  Calcium supplies must be adjusted to needs (400-600 mg/day), in order to avoid hypercalcaemia and calciuria but not too low that stimulates PTH and consequently bone resorption.  Calcium restriction is not effective in hypercalcemia of bone or paraneoplastic origin.  In case of fat malabsorption, the intake of oxalates should be restricted. Fatty acids plus calcium form soaps and free oxalate is easily absorbed in the colon and eliminated in the urine causing hyperoxaluria, with no calcium absorption increase. 26  PHOSPHORUS Metabolism: Intestinal absorption: 50-90%. Renal elimination: 80%. PTH → ↑ renal excretion of P → ↓ [P] pl. Nutritional objectives: Hypophosphatemia: alleviate pluriorganic symptoms. Hyperphosphatemia: improve the toxic-metabolic symptoms. Phosphorus deficiency is rare and hypophosphatemia may be common among older adults due to poor intake in general. It could also develop in individuals who take phosphate binders for renal disease. 27  DIETARY SOURCES OF PHOSPHORUS  In general, good sources of protein are good sources of phosphorus: meat, poultry, fish, eggs, milk, dairy products, nuts, legumes, cereals and grains. 28  Low-phosphorus diets (in hyperphosphatemia) These diets are indicated in hyperphosphatemia secondary to:  The use of phosphorus in laxatives, enemas, supplements, etc..  An important cellular lysis (rhabdomyolysis, tumour lysis).  The tubular reabsorption of phosphorus due to severe dehydration, hypoparathyroidism, hyperthyroidism, acromegaly, etc..  Chronical renal disease Symptoms: Are due to the concomitant hypocalcaemia and soft tissue calcification. Recommendations: Protein reduction, but if high levels of phosphorus remain, P-chelators (calcium, magnesium or aluminium salts) are recommended and the coexistent hypocalcaemia should be corrected as well. 29  High-phosphorus diets (in hypophosphatemia) These diets are indicated in hypophosphatemia secondary to:  Malabsorption.  Chronic intake of aluminium-based antacids.  Reduced dietary intake (this is difficult, so it is better to reduce renal excretion).  Massive entrance of phosphorus into the cells (refeeding syndrome, respiratory alkalosis, too quick intravenous glucose infusion, etc.).  Excessive urinary losses due to alcoholism, hyperparathyroidism (PTH reduces tubular reabsorption of phosphorus), polyuria in diabetic patients or massive burn body.  Treatments with calcitonin: increase renal elimination of phosphorus. 30