Phosphorus 4.3

How abundant is phosphorus

2nd most abundant mineral in the body, a large portion is found in bone and the rest in extracellular fluids and soft tissues

Sources of phosphorus

• milk and yogurt

• cheese

• legumes

• salmon

• tuna

• chicken

Phosphorus is commonly used as a food additive what foods have these additives

• frozen

• breads

• canned veg

• condiments

• soft drinks

who is at great risk for phosphorus toxicity

those with impaired renal function, vit d toxicity, and hyperthyroidism

phosphorus toxicity may result in

mineralization/ harding of blood vessels and nervous tissue

renal failure

hyperphosphatemia may occur- phosphorus restricted diet; some meds to bind phosphorus in the gut to inhibit absorption

steps for digestion, absorption and transport

1. Pi may be absorbed by diffusion

2. Pi may be absorbed by an active Na+/Pi co-transporter (same direction)

factors influencing absorption

• the form of phosphorus in food can help or hinder absorption

• foods that have high amounts of phosphorus in the form of phytic acid have low bioavailability (humans do not have the enzyme needed to metabolize phytates)

how to increase bioavailability

• yeast breads

• soaking beans before cooking

phosphorus fxn and regulation

• found in every cell of the body

• cell membranes attached to protein - free ion

• important for mineralization and strength

structrural roles

dna/rna + phospholipids forms backbone pf molecules polar head region

energy

forms chemical energy from food in high energy bonds/ phosphate bonds in ATP; formation of creatine phosphate (muscle) to replenish energy

signaling compounds

component of “second messengers” molecules that are formed in response to a ligand/ hormone binding cell membrane receptor

acid base balance

intracellular buffer binding or disassociation from H+

oxygen delivery to tissue

required for the release of O2 from hemoglobin to tissues regulation of enzymatic activity phosphorylate lots of vitamins, B6 and thiamin

regulation of phosphorus in the body

three hormones involved in homeostasis

• FGF23

• PTH

• calcitriol

FGF23

fibroblast growth factor 23

• secreted from osteoblasts wants to lower serum levels

• increase secretion in kidneys

• decrease absorption in the gut

PTH

complex relationship

• indirect/ close relationship with calcitriol

what two minerals are the major part of the crystal hydroxyapatite, formed in ossification of bone

phosphorus and calcium

calcitriol

increase leads to increased serum levels

what is a dietary mineral that is an important component of DNA and RNA

phosphorus

foods that commonly have phosphorus as a food additive include

cola, frozen, and bread

how is most of phosphorus regardless of dietary source absorbed from the gi tract

free inorganic phosphate ions