Nutrition Science and Everyday Application - beta v 0.1

Introduction to Bone Health
The human skeleton consists of 206 bones and other connective tissues that together
support and protect many organs, produce red and white blood cells, and act as a storage
depot for minerals such as calcium, phosphorus, and magnesium. Although bones may
look inactive at first glance, they are living tissues that are dynamic and in a constant state
of breaking down and rebuilding to withstand mechanical forces. Bones also contain a
complex network of canals, blood vessels, and nerves that allow for nutrient transport and
communication with other organ systems.
Nutrition influences all body systems, and the skeletal system is no exception. Our lifestyle
choices impact the health of our bones. In this section, we will look at how bone forms
across the lifecycle and discuss the complex interactions of nutrients, hormones, genetics,
and environmental factors that impact bone health.
WHAT IS BONE?
Bone is a living tissue, made mostly of collagen, a protein that provides a soft framework,
and minerals like calcium phosphate that form tiny crystals (called hydroxyapatite) around
the collagen fibers. These inorganic minerals harden the collagen framework and provide
strength. The combination of collagen and minerals makes bone both flexible and strong,
which allows it to withstand stress.
Most bones contain two types of tissue, compact and spongy tissue, but their distribution
and concentration vary based on the bone’s function. Spongy bone (also known as trabecular
bone) is 50 to 90 percent porous and appears as a lattice-like structure under a microscope.
It makes up about 20 percent of the adult skeleton and is found at the ends of long bones, in
the cores of vertebrae, and in the pelvis, as it supports shifts in weight distribution. Compact
bone (also known as cortical bone) is dense so that it can withstand compressive forces. It is
only 10 percent porous, and it looks similar to the rings in a tree trunk, with many concentric
circles sandwiched together. Compact bone tissue makes up approximately 80 percent of
the adult skeleton and surrounds all spongy tissue.
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