Oil, copper, aluminium, precious metals such as gold and silver, even socalled soft commodities such as coffee and soya beans, are all on a roll. It's all about supply and demand.

China and India are consuming resources at a massive rate to fuel breakneck economic growth. But supply cannot be turned on and off at will, especially in the oil and gas industry, which has suffered from decades of under-investment.

The result? A great opportunity for investors to profit while everyone else frets over the earth's dwindling bounty.

The case for commodities is well made by Custom House Capital, an investment intermediary:

"The value of equities and other paper assets can be a matter of opinion. But with fast-developing economies such as China, the increasing and enduring demand for commodities is a matter of fact."

It is offering a six-year commodity bond, open for investment until next Friday, that puts half your money in metals, 40% in oil and gas, and the rest in soft commodities.

The big question for investors is whether it is already too late to cash in on the commodities boom.

Sean Kenzie, investment manager at CHC, believes there is still plenty of oil in the tank, so to speak.

"There's been a bit of froth in the last few months as institutional investors, such as pension funds, got into commodities to diversify away from an over-exposure to equities, " he says. "But, over the longer term, it's the fundamental factors of supply and demand that will drive commodity prices."

He says the sector tends to move in 15-18 year cycles and, because the latest commodity bull run only began in 2001, there is still plenty of upside for new investors.

"Since 1970 the Goldman Sachs commodity index has averaged 12.6% growth per annum, " says Kenzie. "But energy makes up 75%, so we'd expect to beat the index by investing in commodities that haven't moved in a while, such as gold and silver."

While CHC is the only adviser selling a pure play on commodities, many others include a commodity element as part of a broader investment package.

Their key weakness, according to Kenzie, is that they put your money into resource and exploration stocks rather than directly into the commodities themselves. "We give investors direct exposure to an underlying basket of commodities without exposing them to the corporate and stockspecific risk that comes with investing in individual companies, " he says.

Tullow Oil is a good example of what he is talking about. Even as oil prices shoot through the roof, its share price hit the buffers last month after it was forced to abandon wells in Africa and Pakistan.

Kenzie says funds that invest in stocks rather than the underlying assets are being forced to take greater risks in the search for value.

"The easy money has already been made in big companies, such as BP, Anglo American or BHP Billiton so, to get returns, you have to go down the spectrum of smaller companies, which obviously increases risk, " he says.

If you buy the commodities argument, the next question is how much money you should throw at the sector. Kenzie suggests about 10% of your overall portfolio but, because CHC's commodity bond requires a minimum investment of 50,000, only people with assets of over 500,000 should apply.

Other investment advisers believe 10% is way too much. "If you've an appetite for risk and you're prepared to let your investment lie for a few years, you might take a punt on commodities, " says Ian Mitchell, managing director of Deloitte Pensions and Investments.

"But I wouldn't recommend you put more than 1% to 2% of your assets into this area and you should probably avoid it altogether if you're preparing for retirement.

There's absolutely no way of knowing if you're getting in at the right time."

This is why CHC and other fund managers provide a safety net so that, even if the demand for commodities were to slump, you will at least get back your original investment at maturity.

Even then, you should tread carefully says Eamon Porter of Aspire Wealth Management, an authorised adviser.

"Commodities were never promoted before so you've got to ask yourself why, all of a sudden, they're such a big thing.

"Even if the demand for oil and gas looks like a bottomless pit right now, you've got to wonder if the run can continue until your fund matures in three or five years time. Markets are funny and at times they defy logic."