"Investing in food is a simple story: expanding supply and demand fueled by rising global urbanization," says Yiannis Mostrous. In Personal Finance newsletter the global advisor looks at Monsanto (NYSE: MON).

"The global population is expected to surpass 9 billion by 2050. Wages are rising in emerging economies--led by India and China--and more people are moving into cities where the consistent and better paying jobs are.

"That means greater demand for protein-rich foods, especially meat and dairy consumption. The consumption of both has a strong correlation to urbanization. The result will be a permanent increase in demand for crop grains for feeding.

In the past, Richard Lehmann has recommended positions in both energy and agriculture in his Forbes/Lehmann ETF Investor. His latest recommendation is a single fund that invests in both.

The advisor explains, "We've felt that oil prices would likely continue to remain high, mostly because OPEC has control of supply and has become accustomed to $60 plus oil rather than the old $35 target price."

He adds, "We've also recommended positions in agriculture Fund because distortions caused by increased ethanol production has caused an increase in corn prices, which translated to higher wheat and soybean prices as farmers switched production to corn."

Now, he says, there is a fund that tracks not only agricultural commodities but also energy prices at the same time -- the iPath Dow Jones-AIG Commodity Index Total Return ETN (ASE: DJP).

Actually, this "fund" is not an ETF; rather, it is an ETN, or Exchange-Traded Note. Lehmann explains, "ETN's have an advantage over ETF's in that they don't have to pay out distributions and are treated like a zero coupon debt instrument or a promissory note backed by Barclays."

This ETN, he notes, tracks several commodity sectors. According to Lehmann, the fund has 35% invested in the energy sector, 28% in the agricultural sector, 19% in industrial metals and 9% each in precious metals and livestock.

He suggests, "This ETF will tend to be uncorrelated with the broader equity market. Barclays invests in the respective futures contracts and keeps any remaining cash in Treasuries."

Each day, Steven Halpern's TheStockAdvisors.com features the latest investment ideas and market commentary from the financial newsletter community.

For a defensive play that offers exposure to commodities but is not considered vulnerable to the economy, both Mark Skousen and Nick Vardy have added fertilizer producer Potash Corp. of Saskatchewan (NYSE: POT) to their buy lists.

"Steadily increasing demand for ethanol has lead to a 15% increase in U.S. corn plantings, according to the Department of Agriculture," explains Mark Skousen, who points out that crops such as wheat and rice are experiencing high demand as well.

In his Hedge Fund Trader, the advisor says, "As a result, global selling prices for major crops are at their highest level in more than a decade. Farms are pulling out all the stops to maximize production. And the first order of business, of course, is making full use of agricultural fertilizers, chiefly potash."

"Although the ongoing sub-prime scare compounded by private equity financing troubles have dealt markets a severe blow," commodity expert Eric Roseman contends, "This is just another correction in a long series of market hiccups over the last few years."

The editor of Commodity Trend Alert notes, "I doubt what is transpiring now will dramatically alter the secular bull market in commodities and global stocks."

He continues, "Private equity deals have been a big chunk of stock-market volume over the last 12 months. But they're almost small potatoes compared to the massive liquidity rush coming our way, courtesy of global central banks, namely in Asia, with a few trillion dollars' worth of reserves now heading into common stocks."

Roseman explains, "Fed-up with poor returns on dollar-denominated U.S. Treasury bonds, Asian and other central banks and their respective government-sponsored pension funds are starting to direct capital flows to global stock markets to fund future entitlement programs." That move alone, he notes, will ultimately provide an incredible liquidity rush to all markets, including commodities.