Tara Reichenberg says she grew up in a family of unhealthy eaters. As a child, her mother smothered everything in butter while her father refused to eat vegetables. But as she got older, Ms. Reichenberg traded fast food for flax and avocado.

"Right now, I don't think you could pay me to eat at McDonald's," she said, adding that she eats a salad with most meals. "It's just not appealing to me. If they took more care in the preparation as well as buying local and ethically and making healthy foods, then maybe."

Millennials across the country are more aware of their food than ever before, from seeking out farmers markets to fill Mason jars with locally grown produce to lovingly (critics might say, obsessively) photographing meals and uploading them to Instagram. In general, Millennials say they care deeply about where their food comes from and how it is produced. They are more likely to seek out locally grown produce, environmentally sustainable meat, and nutritionally dense superfoods. And given their numbers, corporations are starting to pay attention.

“There are roughly 80 million of them. This makes Millennials the biggest generation thus far. And one thing is for certain, based on research, they are definitely changing the landscape of the food industry,” Chelsea Davis wrote in a blog for TraceGains, a company that provides food manufacturers with the technology to promote quality and safety in the food supply chain.

On Tuesday, in a nod to consumers, food giant Tyson Foods, a company that boasts more than $11 billion in annual poultry sales, announced a deadline for eliminating human antibiotics from its chicken production. The move comes after fast-food chains Chick-fil-A and McDonald’s, responding to widespread concern that consuming human antibiotics in chicken will promote antibiotic resistant strains of bacteria, committed to providing customers with antibiotic-free poultry within the next two to five years. Growing concern about food additives has forced companies to listen up or lose business. And it’s Millennial consumers, known for being pickier about almost everything, who are blazing the trail and demanding more from their food, experts say.

Chicken is far from the only foodstuff affected by the Millennial-driven trend toward food consciousness. Earlier this month, Kraft Foods Group announced it is removing artificial colors and preservatives from its original macaroni and cheese recipe and replacing them with natural spices such as paprika and turmeric. Meanwhile, the Hershey Company is introducing a simpler list of ingredients for the chocolate it sells in the United States, Kellogg's is launching a line of muesli and granola without preservatives or artificial colors and flavors, and Pepsi announced it would stop adding the artificial sweetener aspartame to its diet sodas. McDonald's will be asking customers if they "want kale with that?"

Chipotle received much praise after the restaurant chain announced it would only serve food free of genetically modified organisms. And aside from adding antibiotic-free chicken and kale to its menu, McDonald’s plans to offer milk from cows that have not been treated with the artificial growth hormone rbST. Walmart also opted to expand its selection of organic foods in 2014, leaving some to wonder whether it could cause organic food supermarket chain Whole Foods to lose business.

The shift comes as changes in food consumption habits have driven down profits for many makers of so-called junk food. In January, McDonald's reported a 21 percent decrease in net income during the final quarter of 2014. Soda sales have been steadily declining for the past ten years. In 2014, Coca-Cola reported a 14 percent drop in profits.

Increased awareness about where food comes from and the nutritional value of ingredients has led many young people, like Mike Polans of Boulder, Colo., to adopt a different approach to eating from the way they grew up.

“The biggest shift in my consumption habits happened when I stopped eating meat and became a 'pescatarian' for about seven years," says Mr. Polans, who runs his own food blog.

"I became conscious about avoiding processed food and excess sugar. The way our parents were raised, there are so many sugared drinks. That was the biggest shift I made, cutting out excess junk.”

Meanwhile, the sale of so-called superfoods has skyrocketed. Increased demand for the nutrient-dense kale drove the numbers of farms harvesting the leafy green up from 1,000 to 2,500, according to data from the US agricultural census.

“Millennials look to foods rich in certain vitamins and minerals to support peak performance. Studies demonstrate that Millennials believe that protein is the most important component of healthy eating, but are also interested in switching to healthier oils and consuming nutrient super foods like sweet potatoes, kale, quinoa and blueberries,” the Millennial news site MIC reported.

This interest in quality foods is driven by the fact that Millennials are a generation of “foodies,” observers say. Not only are they more aware of how healthy their food is, they are increasingly concerned with where it comes from, how sustainable its production was, how creatively it was prepared, and how well it photographs.

In January, the Nielsen Global Health and Wellness Survey offered compelling statistical evidence that younger consumers are much more concerned than their parents and grandparents about everything from food ingredients to genetically modified food to organic foods, and they are willing to pay more for premium products. Nearly a third of Millennial respondents said they were willing to pay higher prices for sustainable products; only their younger counterparts (Generation Z) reported placing such value on sustainable food.

“I will often go out of my way to make sure that I am not buying things that are unnecessarily inhumane or questionable, like Tyson or Perdue chicken, for example," says Jon Watson, a clinical research project manager in Massachusetts. "I also do my best to buy cage-free eggs, free-range meats, and wild-caught fish."

“I will certainly go out of my way and spend more money if I know that my money is going to a good, locally grown food purveyor," he added. "I have nothing but disdain for large food conglomerates.”

Of course, not all Millennials have the means to buy organic exclusively, and some readily admit to liking the occasional fast food hamburger. For some, such as Boston-area bike mechanic Malcolm Hall, deciding what to eat is a balancing act.

Mr. Hall’s vegan mother raised him on tofu and peanut sauce, but later in life he says he developed a taste for fast food. Now, as an employee for Boston's bike-sharing program who spends most of his day cycling around Boston, Hall will stop into Wendy’s or other fast-food restaurants to fill up on inexpensive, "calorie-rich" meals.

“I mostly eat this food [fast-food] when I’m working. On my days off or when I’m at home I won’t go out of my way to eat this food. When I’m home I might make turkey, but mostly it’s tofu and greens and stuff,” Hall says on his way out of Wendy's on Massachusetts Ave. “I do really like kale and blueberries and quinoa, but it really depends on what is cost effective at the moment. I try to only shop at Market Basket because any other brand name supermarket is just extremely expensive.”

Another Boston-area Millennial, Amy Block, says she eats as consciously as she can but has to be careful to stay within her limited budget.

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“If I were to spend more money on food it would go toward sustainably-caught fish, meat, and dairy without antibiotics or growth hormone, grass-fed livestock, and locally-sourced vegetables. But I have to balance all that with how I budget,” says Ms. Block, a student in Cambridge, Mass., who works part-time in a hospital.

“Trendy foods that I've bought into include hummus, Sriracha, and kale. They're all so tasty. Hot sauce really improves any dish, and kale tastes healthy. It tastes like I'm performing food penance, which must be benefiting me somehow.”