There are few things in the markets (and life) that you can be sure of. But the fact that all humans get older and, unfortunately, watch their bodies break down is pretty much a given.

So when you consider the aging of America thanks to the aging baby boomer population, you start to see a pretty compelling macroeconomic trend at work. As the U.S. gets grayer, a bigger portion of the population will need maintenance drugs, senior care and hospital services simply as a matter of course.

That adds up to big growth for companies that fill those needs.

Here’s why any long-term investor should pay attention to healthcare stocks right now as part of this decades-long boom in the sector:

• Growing “Customer Base”: Consider that the number of Americans age 55 and older will almost double between now and 2030 if current growth trends keep up — from 60 million, or 21% of the total population, to over 100 million, or 31%. And beyond America there is an opportunity to export innovative care to new markets with an emerging middle class that previously might not have had access to more costly treatments.
• Insurance in Focus: Also adding a tailwind is the implementation of Obamacare. Closing the gap on the number of uninsured in the U.S. means more patients will have health coverage to pay for the treatment they need.
• New Cures Provide New Opportunity: There are many conditions like Alzheimer’s that have no effective treatment — and an effective therapy would be a game changer for Big Pharma as well as for patients. Furthermore, technology provides options including gene therapy and robotic surgery to improve existing treatment with new methods.

Granted, it might sound callous to consider ailing seniors as “consumers,” or to see effective treatments as a way to improve the bottom line instead of improving the quality of life for patients. But it’s worth acknowledging that this is the world we are going to live in — and investors can position themselves for growth by playing the trends.

So how, precisely, do you play this?

Simple: biotech ETFs.

A recent Financial Times tally says that $725 million has been pumped into new biotechnology issues this year, with 10 new players debuting on U.S. exchanges this year and over a half-dozen ready to launch IPOs. There clearly is a revolution here to tap into.

But picking individual players is a fool’s errand.

The dream scenario is a biotech that soars overnight on a breakthrough treatment or a big buyout offer. But the reality is that many stocks crash and burn when treatments prove ineffective or regulators place costly delays or restrictions on their products. In fact, by most industry estimates, roughly 90% of drugs in development wind up falling flat.

However, casting a wide net to play biotechs amid this recent IPO buzz seems to make sense to lots of folks, with biotech ETFs seeing inflows topping $500 million year-to-date — up more than 40% from the total inflows seen in calendar 2012!

So if you’re thinking of joining the party, consider these three funds:

iShares Nasdaq Biotechnology ETF

The iShares Nasdaq Biotechnology ETF (IBB) is a great way to play both upstart drugmakers as well as get exposure to bigger players for some stability. For instance, the top three IBB holdings are Regeneron (REGN), Gilead Sciences (GILD) and Amgen (AMGN), which are collectively worth about $175 billion. These are hardly up-and-coming players, with all running very profitable operations and no risk of going to zero on one bad drug trial.

The IBB fund is up an impressive 22% year-to-date to double the S&P 500 and up about 31% in the past 12 months. And with $3.2 billion in assets and several hundred thousand shares traded daily, this is a legit and liquid fund. IBB will cost you 0.48% in expenses (that’s $48 in fees annually for $10,000 invested).

Learn more about IBB here on the iShares website.

SPDR S&P Biotech ETF

If you want to go slightly smaller, consider the SPDR S&P Biotech ETF (XBI). As the name implies, the fund is benchmarked to a Standard & Poor’s biotechnology index. The XBI also is a modified equal-weight fund (the top holding only is 2.42% of the fund, vs. 0.5% for the smallest holding), which results in greater exposure to many smaller stocks than you get with the IBB. As of right now, only one pick in XBI’s top 10 holdings is worth more than $50 billion — that’d be Biogen Idec (BIIB), which is tied for 10th with $675 million company Dendreon (DNDN). None of XBI’s other top 10 holdings are worth more than $4 billion.

The XBI is up 15% since Jan. 1, outperforming the major indices slightly, and up about the same amount in the past 12 months. It boasts about $920 billion in assets and a slightly smaller expense ratio of 0.35% ($35 annually on $10,000 invested).

Learn more about the XBI fund on the State Street Global Advisors website.

PowerShares Dynamic Biotechnology & Genome Portfolio

If you’re not afraid of taking on a bit more risk, then the PowerShares Dynamic Biotechnology & Genome Portfolio (PBE) is an interesting option. The fund has just 30 holdings; compare that with a whopping 126 biotech stocks comprising the IBB and 52 across the XBI.

The PBE fund is up 23% year-to-date and the same amount in the past 12 months. At a 0.64% expense ratio (that’s $64 a year on $10,000) it’s a bit more costly, but not prohibitively so. With just $170 million under management and much lower trading volume, however, you might want to use limit orders if you trade this ETF just to protect yourself.

Visit PowerShares’ website for more information on PBE.

Jeff Reeves is the editor of InvestorPlace.com. Follow him on Twitter @JeffReevesIP. As of this writing, he did not hold a position in any of the stocks named here.