Investors should take note of a recent consulting group report that predicts health care will account for 20% of the U.S. economy by 2019. Does this mean putting money into any company involved in health care is going to guarantee fat returns? Of course not — nothing’s that simple.

The growing impact of health care on the economy is evident by looking at the Fortune 50: more than three of every four companies are in the industry or have health divisions. Many names are readily identifiable to industry followers: McKesson (NYSE:MCK), CVS Caremark (NYSE:CVS), Unitedhealth (NYSE:UNH) and Big Pharma mainstays Pfizer (NYSE:PFE) and Johnson & Johnson (NYSE:JNJ).

These “traditional” health care companies account for one of every four Fortune 50 members that have a stake in the industry. More than half of the others on the list are entering the field in non-traditional ways.

Dell (Nasdaq: DELL), for instance, believes that information is the foundation on which healthcare will move forward.  Toward that end, the company sells products for electronic medical records, mobile clinical computing and medical archiving. Mobile devices will continue to play a key role in health care and reward the companies that provide innovative hardware and applications. Apple (Nasdaq:AAPL) appears to be the one to catch. According to a recent study, 75% of doctors in the U.S. own an iPhone, iPad or iPod.

The No. 1 company on the Fortune 50 wants to get in on the action, too. Last year, Wal-Mart (NYSE:WMT) partnered with Humana (NYSE:HUM) to offer an innovative Medicare Part D prescription drug plan that can provide significant savings.

The consulting group report goes on to identify four main ways companies might find the best opportunities to make their mark in health care:

• Fixers. Companies that seek to help traditional health companies become stronger by attacking the parts of the health system that are dysfunctional, redundant, bifurcated or unsustainable.
• Implementers. Companies that understand that government spending, new regulations and industry standards shape the healthcare operating environment, and provide ways to assist health organizations.
• Retailers. These companies can bring leading practices for prospering in high-volume, standardized markets with low margins.
•  Connectors. Companies that succeed will be those that link information and technology across the health system.

Walgreen (NYSE:WAG) was cited as one company that is doing a superb job of expanding its health care offerings. The company is boosting retail sales through new wellness products, so-called nutraceuticals, and durable medical equipment product offerings. And the Take Care Clinics Walgreen acquired three years ago are now offering more preventive services.

It’s clear that health care will continue to offer excellent opportunities to the discriminating investor. However, as the reports cautions, “The healthcare industry is not for the faint of heart. It is complex and turbulent, and it operates on basic principles foreign to companies successful in other industries.”