people maynot realizethat theyhavecavity and gum
problemsuntil it’s too late. Inthe course ofa normal
lifetime,themusclesofthejawloseabout 40 percentof
theirmassandthebonesofthemandibleloseabout 20
percent,becomingporousandweak.Theabilitytochew
declines, and people shift to softer foods, which are
generallyhigherinfermentablecarbohydratesandmore
likelytocausecavities.Bytheageofsixty,peopleinan
industrializedcountryliketheUnitedStateshavelost,on
average,athirdoftheirteeth.Aftereighty-five,almost 40
percent have no teeth at all.
Evenasourbonesandteethsoften,therestofourbody
hardens.Bloodvessels,joints,themuscleandvalvesof
theheart,andeventhelungspickupsubstantialdeposits
ofcalciumandturnstiff.Underamicroscope,thevessels
andsofttissuesdisplaythesameformofcalciumthatyou
findin bone.Whenyoureachinsideanelderlypatient
duringsurgery,theaortaandothermajorvesselscanfeel
crunchyunderyourfingers.Researchhasfoundthatloss
ofbonedensitymaybeanevenbetterpredictorofdeath
from atheroscleroticdiseasethancholesterollevels. As
weage,it’sasifthecalciumseepsoutofourskeletons
and into our tissues.
Tomaintainthesamevolumeofbloodflowthroughour
narrowed and stiffened blood vessels, theheart has to
generateincreasedpressure.Asaresult,morethanhalfof
us develop hypertensionby the age of sixty-five.The
heart becomes thicker-walled from having to pump
against the pressure, and less able to respond to the
demands of exertion. The peak output of the heart
thereforedecreasessteadilyfromtheageofthirty.People