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In the year 2000, approximately 2.5 million Americans turned 65. This year, more than 3.5 million Americans will pass that milestone. And the number of people joining the ranks of the elderly will keep increasing, at least for the next 20 years, as more and more baby boomers hit their 60s, 70s and 80s. By 2030, the over-65 crowd will expand to 72 million people, up from 40 million in 2010.

The increasing numbers of recent retirees, along with the hordes waiting at the gates, give politicians headaches as they try to figure out how to finance Social Security and pay the health care bills covered by Medicare.

But for those of us looking to invest in the American economy, this burgeoning population means an increasingly lucrative market for products and services focused on the elderly. By the time they're done, some 78 million baby boomers will have survived millions of hip replacements and heart transplants, swallowed trillions of Advil and Viagra pills, and consumed billions of boxes of bran and packages of prunes.

Despite the faltering economy of the past five years, American seniors are richer than ever, in large part because more older people, especially older women, are working than in previous decades. According to a 2012 report from the Federal Agency Forum, the number of senior citizens living in poverty has declined from 15% to 9% since the mid-1970s, while the proportion of older Americans enjoying a "high income" increased from 18% to 31%.

So even while the burgeoning number of retirees will strain government resources, they will provide enormous moneymaking opportunities for public companies. These people will travel. They will move to warmer and friendlier climates. Many will manage their individual retirement accounts and 401k's through financial institutions. They will buy long-term care insurance, pay rent to senior citizen facilities and drop an average of $8,000 per funeral.

At least one financial firm -- JPMorgan -- has taken the trend seriously enough to create an "Aging Population Index" of stocks expected to profit from baby boomers. The list comprises more than a dozen individual companies, from drugmaker Celgene to hotel chain Wyndham Worldwide. These stocks may or may not be good investments. Unless you read their balance sheets and income statements and know something of their plans, how would you know?

The smart way to invest in baby boomers is to identify a trend, then let a reputable expert pick the specific companies that will likely benefit from those prevailing winds. Here are three ideas:But with 78 million baby boomers retiring, can you be wrong?

Medical care

It doesn't take hard-won experience to realize that older people use more medical products than younger people do. The average 70-year-old gulps about three times more prescription drugs than the typical 40-year-old. Vanguard offers the mutual fund Vanguard Health Care (VGHCX), managed by Jean Hynes, that provides intelligent and low-cost exposure to the industry. Fidelity has its FidelitySelect Pharmaceuticals (FPHAX) and FidelitySelect Biotechnology Portfolio (FBIOX) funds, the latter helmed by Rajiv Kaul. There are also several medical care exchange-traded funds, including Vanguard Health Care (VHT).

Finance and insurance

Retirees are increasingly responsible for their own savings, income and financial futures. Money managers are developing more and more products to meet this need, including annuities, reverse mortgages and other asset management tools. But again, are you in a position to know whether JPMorgan or Morgan Stanley is the better investment (or even know the difference between the two)? Vanguard has an ETF, called Vanguard Financials (VFH), that invests in more than 400 financial stocks. Schwab also has a financial mutual fund; the Burnham Financial Services (BURKX) fund is another possibility.

Consumer products

Older people may not buy that many jeans or video games, but they do purchase personal care products, including wrinkle creams, special cleansers and adult diapers. Vanguard offers an ETF called Vanguard Consumer Staples (VDC). The Rydex Consumer Products Fund (RYPDX) is another choice. These funds invest in companies like Procter & Gamble, which cooks up the fiber supplement Metamucil, and Kimberly-Clark, which deals out Depends.

There's no guarantee that investing in any of these funds will produce better results than putting your retirement savings in a low-cost index fund. But with 78 million baby boomers retiring, can you be wrong?

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