This article is part of our Rising Star Portfolio series.

Last week's news that Facebook founder Mark Zuckerberg has been eating only meat that he's killed himself might have seemed shocking to those who heard the news while devouring their morning eggs and sausage. I admit it: My first mental image was of that Facebook guy brandishing a club, drenched with blood and gore from the kill. What a perfect capitalistic symbol!

In all seriousness, that news item isn't about the competitive ruthlessness often attributed to Mark Zuckerberg (see: The Social Network), but far more humane issues. Zuckerberg's raising awareness for sustainable eating.

Killing any animal, whether or not it shows up on a plate, may not sound particularly kind or humane. However, more and more consumers are becoming aware that factory farming is a particularly brutal and horrific business, even if the public is sheltered from the reality of what goes on in slaughterhouses.

Sustainability: a sign of the times
Even if many consumers weren't "there" yet, some companies have been ahead of the curve on animal welfare and general sustainable farming methods over the years:

  • Whole Foods Market (Nasdaq: WFM) recently launched animal welfare labeling for its meats, after years of development.
  • Chipotle's (NYSE: CMG) Food with Integrity mission has always consisted of using naturally raised ingredients as often as possible.

Meanwhile, more "conventional" companies have increasingly pursued major sustainability initiatives:

  • Wal-Mart (NYSE: WMT) vowed to use more local produce.
  • Safeway (NYSE: SWY) scored the No. 1 slot in Greenpeace's recent report on seafood sustainability.

Shareholder activism has played a significant role in the big changes now taking place. The Humane Society of the United States, a major shareholder proponent of cage-free eggs, spoke on the topic at McDonald's (NYSE: MCD) latest annual meeting. The organization recently gave companies like Burger King, Subway, Royal Caribbean (NYSE: RCL), and Unilever (NYSE: UL) Corporate Progress Awards for meaningful switches to cage-free eggs.

In addition, McDonald's has taken what the Humane Society calls an "initial positive step" with its intention to buy 12 million cage-free eggs for its U.S. restaurants this year. (It already uses cage-free eggs in Europe.) While that figure represents a heck of a lot of eggs laid by a heck of a lot of hens, it actually amounts to only 1% of the fast food giant's total U.S. egg use.

Sustainability: a sign of the (changing) times
Trust me, these topics do relate to Zuckerberg's choice to slaughter his own food.

His dietary choice ups the awareness of sustainable living. According to the media reports, Zuckerberg's decision to eat only meat that he slaughters himself has unsurprisingly led him to consume far less meat.

As a high-profile person, Zukerberg's highly publicized dietary decision gives the public something to chew on. Buying prepackaged meat in the supermarket is easy (if somewhat expensive these days), but it's hardly an honest acknowledgment of what goes on behind the scenes when animals are slaughtered. Say what you will about Zuckerberg, but he's eating meat with a full understanding of how it got to his plate.

Meat-centric diets embody a heavier carbon footprint than diets that reduce or even avoid meat consumption. A little more conscious eating might do us all a lot of good (and help to push for more sustainable, less wasteful practices in the food industry).

Companies like Whole Foods and Chipotle have been way ahead of the curve in recognizing the ethical considerations inherent in our food choices. That's why they're particularly high in the universe of stocks I consider for my Rising Star portfolio. (I bought shares of Whole Foods for the portfolio in May.) Companies that seek more humane profits get me most jazzed for the long term.

Issues once dismissed as weird and extreme now enjoy greater awareness among consumers. Investors had better hope their companies are ready for increasingly conscious audiences, who think a bit more deeply about the impact of what and how they consume.

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The Motley Fool owns shares of Chipotle, Wal-Mart, and Whole Foods Market. Motley Fool newsletter services have recommended buying shares of Whole Foods Market, Unilever, McDonald's, Chipotle, and Wal-Mart. Motley Fool newsletter services have recommended creating a diagonal call position in Wal-Mart. Try any of our Foolish newsletter services free for 30 days.

Alyce Lomax is a guilty flexitarian who owns shares of Whole Foods Market. For more on this and other topics, check back at Fool.com, or follow her on Twitter: @AlyceLomax. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy. Try any of our Foolish newsletter services free for 30 days.