Use "title" attribute

Title attribute can add information so that the link is more predictable and able to be differentiated from others.

<p>Adequate levels of 
<a href="http://www.mayoclinic.com/health/vitamin-d/NS_patient-vitamind" 
title="More information from the Mayo Clinic about vitamin D">vitamin D</a> 
during young adulthood may reduce the risk of adult-onset 
<a href="http://www.diabetes.org/diabetes-basics/type-1/"  
title="More information from the American Diabetes Association about type 1 diabetes">type 1 diabetes</a> 
by as much as 50 percent, according to researchers at the 
<a href="http://www.hsph.harvard.edu/" 
title="Harvard T.H. Chan School of Public Health brings together dedicated experts from many disciplines to educate new generations of global health leaders and produce powerful ideas that improve the lives and health of people everywhere." >Harvard School of Public Health</a> 
(HSPH). If confirmed in future studies, the findings could lead to a role for vitamin D 
supplementation in preventing this serious autoimmune disease in adults.</p>

Rendered

Adequate levels of vitamin D during young adulthood may reduce the risk of adult-onset type 1 diabetes by as much as 50 percent, according to researchers at the Harvard School of Public Health (HSPH). If confirmed in future studies, the findings could lead to a role for vitamin D supplementation in preventing this serious autoimmune disease in adults.

Copyright © David Heitmeyer