When you think of your exchange traded fund (ETF) portfolio as a recipe that calls for various ingredients, things can take on a new meaning.

To give a recipe a twist, sometimes there’s the "secret ingredient." With ETFs, commodities are it. They have a low-to-negative correlation to nearly every other asset in the typical portfolio, says Craig L. Israelsen for Advisor Perspectives. The more assets you can assemble in your portfolio that have a low correlation with one another, the more successful you will be.

Commodities are what’s driving globalization, and their prices are shaped by long-term supply and demand. Many businesses produce commodities, and investors wouldn’t think twice about owning those businesses in their portfolios.

But businesses can go bankrupt. Commodities can’t.

No one can predict what anything will do in the future, including when it comes to commodities. But as long as they share almost no correlation with other asset classes, they’re worth a look.

There are a number of ETFs that provide access to a host of commodities, including:

• Market Vectors Agribusiness ETF (MOO)
• PowerShares DB Agriculture (DBA)
• PowerShares Dynamic Food & Beverage (PBJ)
• PowerShares DB Commodity Index Fund (DBC)
• PowerShares FTSE RAFI Basic Materials (PRFM)
• United States Oil (USO)
• United States 12 Month Oil (USL)

Tags: Agriculture, Commodity ETFs, DBA, Food & Beverage, Israel, Material ETFs, Metals & Mining, USO