One year after young adults were given the right to be insured under their parents' insurance plans under Obamacare, many were reported to be in excellent health both physically and mentally.

The 2010 federal health law allowed young adults to join or remain on their parents' insurance plans and those who did said they are in a better mental and physical state of health compared to those who did not. Those who were able to be covered under the health insurance plans of their parents until 26 years of age under the Affordable Care Act spent less on healthcare.

The coverage is linked with a 6.2 percent gain in the likelihood that young adults will report excellent health. Meanwhile, there is also a four percent increase in mental health among these young adults compared to a control group of older peers who did not benefit from this law.

"I think our study suggests it improved health and reduced exposure to healthcare costs," study lead author and Boston Children's Hospital pediatrician Dr. Kao-Ping Chua said. "I think the larger question of cost versus benefit requires further study, but there do appear to have been significant benefits."

Harvard School of Public Health and Boston Children's Hospital researchers surveyed over 26,000 young adults between 19 and 25 years of age before and after Obamacare was implemented. The study found that 6.2 percent reported excellent health and 4 percent reported excellent mental health in 2011 compared to 10 years earlier. 31 percent of the 19 to 25 years old group reported excellent physical health compared to 27 percent between 2002 and 2009. The control group who were aged between 26 and 34 said there was not much change in their health.

According to researchers, people who know they have health insurance feel more secure and it can improve their mental health. The reason for the improvement on physical health is still unclear but it could be because these people receive more health care benefits.

The study suggests that those who were not allowed to join their parents' health insurance plans will receive the same benefits through private coverage enrollment under the new Obamacare marketplaces or Medicaid expansion.