NEW YORK ( ETF Expert) -- Timber has been weak since the Federal Reserve announced its enormous bond-buying initiative. Agricultural grains have been even weaker since the peak of drought fears in mid-July. And crude oil? Instead of surging past $100 per barrel, it closed at less than $88 per barrel on Oct. 3.The question is simple: If gurus from Jim Rogers to Bill Gross to Kyle Bass believe real assets belong in your portfolio, should you buy them now ... when they are down below recent 52-week highs? By the same token, which real asset ETFs make the most sense for income generation, capital appreciation and/or inflation protection? Following are some real asset ETFs, followed by their month-over-month returns and the percentage they're off their 52-week highs: PowerShares DB Industrial Metals ( DBB), 8.7%, -8.9% Guggenheim Timber ( CUT), 5.5%, -4.8% S&P Global Natural Resources ( GNR), 5.5%, -8.2% iShares Gold Trust ( IAU) 4.9%, -0.5% SPDR Dow Jones Global Real Estate ( RWO), 0.3%, -4.2% Vanguard REIT ETF ( VNQ), -2.3%, -4.6% PowerShares DB Commodity ( DBC), -2.5%, -5.6% ELEMENTS Rogers Internat Comm Agriculture ( RJA), -3.5%, -5.7% PowerShares DB Oil ( DBO), -7.4%, -21.5% Teucrium Soybean ( SOYB), -10.6%, -10.1% iShares Gold Trust ( IAU) may be the safest and least volatile inflation-fighter in the mix. There's simply no denying that China is massively stockpiling the yellow metal and that the world's central banks are determined to devalue paper money. Greater demand, less supply ... Gold also has the potential for capital appreciation. Yet precious metals fail to inspire on the income generation front. Here's where real estate investment trusts, or REITs, have been making believers out of skeptics. Not only are REITs required to distribute 90% of taxable income, making them a popular cash flow generator, but REIT prices often go up with inflation. (Leases/rents that may be indexed to inflation comprise the majority of REIT income.) That said, Vanguard REIT ( VNQ) and SPDR Dow Jones Global REIT ( RWO) have been anemic over the last 30 days. The VNQ-SPY price ratio shows that domestic REITs haven't been this weak relative to U.S. stocks in roughly six months.