Nutrition Science and Everyday Application - beta v 0.1

500 ALICE CALLAHAN, PHD, HEATHER LEONARD, MED, RDN, AND TAMBERLY POWELL, MS, RDN
of which are controllable and some of which are not. It is thought that genetic factors (such
as sex and race) may account for up to 75 percent of bone mass, and lifestyle factors (such
as diet and exercise habits) account for the remaining 25 percent. 2
Osteoporosis risk factors that are biological and can’t be controlled:
• Body frame size- People with small frames are at higher risk for osteoporosis.
• Race- Caucasian and Asian populations are at higher risk of osteoporosis
compared to African American and Hispanic populations, which are at lower risk. 1
• Family history– Having a family member with osteoporosis may increase risk, as
heredity seems to play a part in the development of osteoporosis.
• Age- After age 40, bone mass declines due to bone breakdown exceeding bone
formation. Therefore, any person over the age of 40 has an increased likelihood of
developing osteoporosis compared with a younger person. Starting out with a
higher peak bone mass in early adulthood enables you to lose more bone during
the aging process and not develop osteoporosis.
• Sex- Females, on average, have a lower peak bone mass compared with males (see
Figure 9.3) and a much greater risk of developing osteoporosis, in part because of
hormone levels.
• Hormones- The female hormone estrogen and the male hormone testosterone
both help to increase peak bone mass. Estrogen is the primary female
reproductive hormone, and it stimulates bone building and reduces bone
breakdown. When women go through menopause (usually around age 50), they
experience a natural decline in estrogen levels, which accelerates bone loss and
increases the risk of developing osteoporosis (Figure 9.3).