US President Barack Obama said five years after the Affordable Care Act was implemented, the lives of Americans are better contrary to the "doom-and-gloom predictions" of its critics.

"So five years in, what we are talking about it is no longer just a law. It's no longer just a theory. This isn't even just about the Affordable Care Act or Obamacare. This isn't about myths or rumors that folks try to sustain. There is a reality that people on the ground day to day are experiencing. Their lives are better," said Obama in his speech at the Catholic Health Association Conference in Washington, D.C. on Tuesday.

Obama said since the Act's implementation, "nearly one in three uninsured Americans have already been covered — more than 16 million people — driving our uninsured rate to its lowest level ever. Ever."

In addition, he said, tens of millions enjoy new protections with the coverage they already have.

"That 85 percent who had health insurance, they may not know that they've got a better deal now than they did, but they do. Americans can no longer be denied coverage because of pre-existing conditions — from you having had cancer to you having had a baby. Women can't be charged more just for being a woman. And they get free preventive services like mammograms. And there are no more annual or lifetime caps on the care patients receive," he said.

The US Supreme Court is set to rule on a lawsuit against Obamacare, known as King vs. Burwell, about a phrase that allows tax credits for state-run exchanges.

Obama said critics' prediction against Obamacare including the "unending Chicken Little warnings that somehow making health insurance fairer and easier to buy would lead to the end of freedom, the end of the American way of life" did not happen.

"None of this came to pass. In fact, in a lot of ways, the Affordable Care Act worked out better than some of us anticipated," he said.

He added that Medicare has been strengthened with the addition of 13 years to its actuarial life.

"The financial difference for business owners trying to invest and grow, and the families trying to save and spend — that's real, too. Healthcare prices have risen at the lowest rate in 50 years. Employer premiums are rising at a rate tied for the lowest on record. The average family premium is $1,800 lower today than it would have been had trends over the decade before the ACA passed continued," the President added.

Obama said there's more work to do including new policies "to make healthcare work even better" and bring down the costs.

"And none of this is going to be easy. Nobody suggests that somehow our health care system is perfect as a consequence of the law being passed, but it is serving so many more people so much better," he said.