Phosphate

Question 1

Role of phosphorus in body

Answer 1

Present in all cells in body releasing energy to cells when needed in form of ATP
Helps maintain skeletal rigidity
Phosphate balance maintained by adequate renal excretion in health

Question 2

Phosphorus vs phosphate

Answer 2

Phosphorus - found with other elements
Phosphate - phosphorus and oxygen - measured in blood

Question 3

Why might low phosphate diet be required?

Answer 3

Primary reason - advanced chronic kidney disease (CKD)
Kidneys remove excess phosphate to maintain blood levels between 0.9-1.4 mmol/L
CKD - bone metabolism is altered and phosphate is not adequately excreted - build up in blood
High phosphate levels linked with renal bone disease and increased morbidity/mortality rates in renal patients

Question 4

Principles of a low phosphate diet

Answer 4

Reduce dietary intake to 800-1000mg per day
Ensure adequate intake of protein, calories and other nutrients is maintained

Question 5

Important to control foods with a high phosphate content per gram of … whilst maintaining an adequate … intake

Answer 5

Protein

Question 6

Sources of phosphate in food

Answer 6

Organic - naturally occurring phosphate
Inorganic - phosphate additives

Question 7

Dietary absorption of phosphate

Answer 7

Animal products 40-60%
Whole grains/nuts 20-50%
Additives 90-100%

Question 8

Organic and inorganic sources of phosphate differ in their … and …

Answer 8

Bioavailability and absorption

Question 9

Organic phosphate - animal/fish sources

Answer 9

Dairy products - cheese, milk, yogurt
Eggs
Meat - offal e.g. liver and kidney
Oily fish e.g. mackerel, salmon and trout
Seafood e.g. prawns and squid
Limit - not complete avoidance
Can make up over 50% phosphate intake in non-vegetarian western diet

Question 10

Organic phosphate - plant sources

Answer 10

Cereal grains
Nuts
Seeds
Pulses
Chocolate
Present as phytate - most likely inactivated by food processing and heat

Question 11

Alcoholic drinks

Answer 11

Wine - phytate present in grape seed
Larger and beers - phosphate released from grains during fermentation

Question 12

Inorganic phosphate - phosphate additives

Answer 12

Prevalent in processed foods and drinks
Amount of phosphorus in foods has doubled since 1990s
Phosphate additives found to be present in 44% best selling food and beverages

Question 13

Foods that may contain phosphate additives

Answer 13

Meat and poultry products e.g. sausages
Bakery products
Seafood products
Processed cheese
Dried or powdered food items
Non-alcoholic drinks
Potato products
Dairy products

Question 14

How to identify phosphate additives in foods

Answer 14

Not included in food composition data or tables
Only organic reported
PHOS or E numbers
Difficult for consumer - provide guide list of E numbers

Question 15

Practical applications

Answer 15

Individual dietary assessment
Replace foods
Limit high phosphate containing foods
Avoid processed foods where possible
Cook from fresh
Avoid high phosphate foods of low nutritional value

Question 16

Issues with a low potassium diet

Answer 16

Difficult for people who mainly consume convenience foods - may not have money/facilities/cooking skills
Difficult to maintain protein if vegetarian or on a different diet

Question 17

Considerations

Answer 17

Adequate protein intake
Nutritional status - not appropriate if malnourished
Clinical condition and age
Social circumstances
Education ability and vision
Updated recipes from food manufacturers

Question 18

Organic phosphate from cereal and grains is not highly available especially if … or … processed

Answer 18

Cooked or heat processed

Question 19

Cereals and grains provide positive … benefits and may prevent …

Answer 19

Nutritional and constipation