As the U.S. stock market continues to break all-time highs seemingly by the day, investors might be wary of committing new capital to stocks. After all, the underlying economy isn't improving nearly to the extent the stock market seems to imply. Even famous investor Carl Icahn recently stated his own reservations about the market, going so far as to say that U.S. stocks could face a big drop.

At the same time, a few best-in-breed consumer staple giants generate reliable profits year in and year out, thanks to the strength of their core brands. Such stocks include Procter & Gamble (NYSE:PG), Kimberly-Clark (NYSE:KMB), and Clorox (NYSE:CLX). Here's why investors would be wise to consider these three great companies, especially if the market is about to decline.

Great brands mean great results
P&G points investors to its 50 Leadership Brands, which together account for 90% of the company's products. Just a few of P&G's stable of world-class brands include Bounty, Pampers, Tide, Gillette, Charmin, and Crest. Half of these 50 Leadership Brands generate more than $1 billion in annual sales each, which means P&G has a well-diversified portfolio.

P&G's underlying results speak for themselves. The company generated $84 billion in fiscal 2013 net sales, and grew diluted earnings per share by 5%.Then, P&G followed up that performance with a strong fiscal 2014 first quarter, growing sales and diluted EPS by 2% and 8%, respectively.

Kimberly-Clark is the consumer goods giant behind such brands as Huggies, Kleenex, and Cottonelle. Kimberly-Clark had a strong third quarter, generating 5% growth in sales after excluding the impacts of currency fluctuations. Moreover, Kimberly-Clark increased the lower end of its full-year earnings guidance, and now expects to earn $5.70 per share, at the midpoint of its EPS expectations. That would represent 28% growth over its full-year 2012 EPS.

Meanwhile, Clorox is a much smaller company by market capitalization than P&G or Kimberly-Clark, but the strength of its best brands is no less impressive. Clorox recently celebrated its 100th year anniversary, and along the way it has built its own portfolio of popular products. Its core brands include its namesake bleach as well as Pine-Sol, Kingsford, Glad, and Hidden Valley.

Nearly 90% of Clorox's brands hold number one or number two positions in their respective categories, and the company's results prove its strength. Clorox reported 2% growth in net sales and 3% growth in diluted EPS in its fiscal first quarter.

Fortunately for investors, P&G, Kimberly-Clark, and Clorox are highly committed to sharing their success with shareholders. Consider that this year marks the 123rd in a row of consecutive dividend payments from P&G, since the company's incorporation in 1890. Furthermore, P&G has increased its dividend for 57 years in a row. At the same time, Clorox recently raised its dividend for the 36th consecutive year. And, for its part, Kimberly-Clark has increased its dividend for 41 years in a row, and has paid dividends for 79 consecutive years.

Could the stock market really face a big drop?
That's the opinion of noted activist investor Carl Icahn, and it's likely many investors feel the same. The simple truth is that of course the stock markets could drop. It's impossible to know exactly what the future holds.

At the same time, great companies like Procter & Gamble, Kimberly-Clark, and Clorox keep raking in reliable profits, regardless of how the broader economy is doing. They continue to maintain world-class brands that consumers have a very hard time going without. Moreover, they return considerable portions of their profits to shareholders through dividends, which keep going up year after year.

As a result, buying consumer staple giants like P&G, Kimberly-Clark, and Clorox can lower your portfolio volatility. The margin of safety provided by their strong brands and hefty dividend yields mean these three great stocks should be in focus if you think we're about to enter a market downturn.