Source: Illumina.

Right now might be to healthcare what the early 1990s were to the Internet: an era on the cusp of a true industry transformation. What will healthcare look like in the years ahead -- and how can investors succeed with the changes? Here are three of the best stocks for investing in the future of healthcare.

1. Illumina (ILMN -2.42%)
While the term "precision medicine" received a lot of hype with President Obama's 2015 State of the Union address, the concept of customizing healthcare for an individual patient has been around longer. And you probably can't find a company leading the way more powerfully for precision medicine than Illumina.

Source: Illumina.

One key to achieving the objectives of precision medicine is understanding each person's genetic makeup. Illumina's next-generation sequencing systems are making that possible.

The company's HiSeq X Ten genomic sequencing system allows an entire genome to be sequenced for around $1,000. To put that into perspective, the first sequencing of the human genome took more than 10 years ago at a cost of more than $3 billion.

Illumina is partnering with several of the world's largest pharmaceutical companies to develop a universal test system to identify specific cancer-causing genes in individuals that helps streamline the drug-development process. The technology ultimately could help physicians use patients' genetic information to help prescribe targeted medicines most effective at treating their diseases.

2. UnitedHealth Group (UNH -0.76%)
Another hot healthcare technology gathering big momentum is telehealth. There are quite a few companies offering telehealth products to connect patients to the care they need via telecommunication technologies. I think a smart way to profit from this wave is to buy shares of a company poised to experience lower costs as use of telehealth technology soars -- regardless of which vendor prevails. As the nation's largest health insurer, UnitedHealth Group certainly fits the bill.

When its medical costs are lower, UnitedHealth's bottom line improves. The promise of telehealth is that it can hold healthcare costs down by allowing patients to see medical professionals virtually. Last month, UnitedHealth announced partnerships with three companies to cover video doctor visits just like it covers in-office visits.

Source: NowClinic.com.

One of those partnerships is actually with UnitedHealth's own business unit, Optum. NowClinic is a telemedicine service offered by Optum that connects patients with healthcare providers via a PC or mobile device. The service is currently available in 45 states plus the District of Columbia.

3. Apple (AAPL 0.20%)
Monitoring patients' health in their daily lives is certain to become increasingly important. That's where wearables technology comes into play. While there could be several winners in the market for healthcare wearable technology, one of the biggest could very well be that "fruit company" that Forrest Gump liked so much -- Apple.

Source: Apple.

It's too soon to know exactly how big an impact the new Apple Watch will have on healthcare, but expect the technology giant to learn a lot from its first wearable on the market. Just as the iPod seems primitive now in comparison with the latest iPhone version, Apple will likely launch wearables during the next few years that offer significantly more health-related functionality.

Wearable technology isn't the only way that Apple will play a role in the future of healthcare. The company's products have already revolutionized the industry.

Physicians use iPads and iPhones to find clinical information at the point of care. Apple's AppStore includes thousands of healthcare applications. As its products become even more advanced, expect their healthcare capabilities to grow.

Valuing the future
To some extent, these companies' future healthcare prospects have already been baked into share prices. Illumina reflects this the most, with a price that is more than 46 times forward earnings estimates. Despite this lofty valuation, though, analysts expect that Illumina's stock could climb more than 20% in the next year.

UnitedHealth has a forward price-to-earnings multiple of 16. And even though shares are up more than 50% during the past 12 months, Wall Street still thinks the health insurer's stock has room to move another 20% higher during the next year.

Apple's valuation appears to be the most attractive, with a forward earnings multiple of 13. Analysts aren't quite as bullish on Apple as they are on Illumina and UnitedHealth, but they still expect the stock to rise around 15% in the next year.

Of course, predicting the future is tricky. Those analysts' estimates could be overly optimistic. Companies other than Illumina, UnitedHealth, and Apple could emerge as the biggest healthcare winners. At this point, however, all three have solid business models, and should benefit from key healthcare trends that don't seem likely to fizzle out.