Fools may want to pay attention to a specific subset of the U.S. commercial real estate investment trust (REIT) industry to nab future gains.

The commercial real estate market showed signs of growth in 2010 and is expected to do even better in 2011. However, a careful analysis shows that not all sectors of the REIT industry have been showing positive signs. Higher commercial vacancy in the U.S. real estate market makes some of the sectors still look quite bleakish, but a few areas look promising enough -- and the health-care REIT sector is definitely one of them.

Health care beats its siblings
During the slump, health-care REITs did not decline as much as other REITs, and now they are outperforming their counterparts. While retail stores, manufacturing facilities, and offices are still struggling, large health-care REITs are growing larger with multibillion-dollar acquisitions and attracting more investors than ever.

Part of the rationale behind this is obvious; while discretionary shopping demand is quite susceptible to all sorts of economic pressures, one's health-care expenses are always a top priority. Naturally, managers of medical offices and spaces are dealing in a product that surely is more defensive in nature and surely will only grow as time goes on, given various demographic changes in the American population.

In 2010, the sector announced acquisitions worth $11.25 billion, with HCP (NYSE: HCP) agreeing to buy HCR Manor Care for $6.1 billion. Ventas (NYSE: VTR), which seems to have adopted an aggressive growth strategy, is buying Nationwide Health Properties (NYSE: NHP) for about $5.7 billion in stock, forming the biggest health-care REIT in the U.S.

Ventas had struck four deals last year; with this deal in its kitty, it will become the largest owner of assisted-living housing in the country. This is a move to lower the company's overall debt and, as Chief Executive Debra Cafaro puts it, Ventas wants to "have the best balance sheet around."

Health Care REIT (NYSE: HCN) has agreed to buy the real estate of Genesis Healthcare for $2.4 billion. It will buy all of Genesis' real estate assets and also have the right to buy a 9.9% stake in Genesis for $47 million.

The able heir of the family
The health-care REIT sector has room for consolidation, and a lot of positive drifts are combining to give it a boost. Cafaro expects more consolidation within the sector. The U.S. health-care real estate market is worth more than $700 billion. But not even a tenth of this is currently owned by the few listed trusts. The sector is expected to witness growth as 70 million baby boomers age and stimulate demand for health-care services.

The aging of the population is a strong fundamental economic trend. The number of Americans age 65 and older is expected to grow 36% between 2010 and 2020, compared to a 9% growth rate for the general population. President Obama's health-care overhaul is also boosting the number of people with health insurance. These factors are turning institutional investors to the health-care REITs. General speculation on acquisitions has already pushed up shares of smaller REITs like Universal Health Realty (NYSE: UHT), Cogdell Spencer (NYSE: CSA), LTC Properties, and Omega Healthcare Investors (NYSE: OHI).

Foolish bottom line
As you can see, there is a lot of consolidation in the industry, perhaps because top names see a bright future along with cheap valuations, and they wish to bulk up their balance sheets before entering the next bull market for real estate. It's just a theory, but it certainly seems plausible.

Spending cuts in government reimbursements for health-care programs may adversely affect this sector in the short and perhaps medium term. But the positive trends in acquisitions and investments are expected to drive growth in the health-care REIT sector well into the future.

Given the nature of the end product being sold here, the sector appears somewhat invulnerable to short-term fluctuations and, considering its multiple demand drivers, I choose to remain bullish on it.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.