KANSAS CITY — The origination of the mainstream bar category can be traced back to the 1970s, when General Mills, Inc., after recognizing that people were eating its Natural Valley Granola cereal as a snack, introduced a crunchy granola bar under the same name. Several years later the Quaker Oats Co. debuted Quaker Chewy Granola Bars, and the emergence of a new category had begun.

More than 40 years later General Mills and Quaker Oats still stand atop the granola bars category, with sales exceeding $749 million and $379 million, respectively, in the 52 weeks ended Oct. 7, according to Information Resources, Inc., a Chicago-based market research firm.

But granola bars, once the shining star of the bars category, have lost some of their shine. In the 52 weeks ended Oct. 7, dollar sales of the granola bars category totaled $1.63 billion, down nearly 3% from the same period a year ago, according to I.R.I. Unit sales have dropped 3.6% over the past 52 weeks.

The decline in the granola bars category is not reflective of the strength in the bar segment overall, though. In the 52 weeks ended Oct. 7, dollar sales in the snack bars/granola bars category were $6.24 billion, up 2.9% from the same period a year ago. The sector has received a strong boost from nutrition and health bars, which grew 3.5% to $3.2 billion in sales in the 52 weeks ended Oct. 7, and breakfast/cereal/snack bars, which increased 9% to $1.4 billion, according to I.R.I.

Recognizing the potential of the health bar segment, PepsiCo, Inc., Purchase, N.Y., in late October acquired Health Warrior, Inc., the maker of plant-based nutrition bars and other products.

“This acquisition helps us increase our presence in the nutrition bar category, which is an attractive growth space,” said Albert P. Carey, chief executive officer of PepsiCo North America.

Founded in 2011 by three college athletes and friends, Health Warrior’s flagship product is a chia seed-based snack bar. The company has since followed with pumpkin seed-based bars, superfoods protein powder featuring probiotics, and protein mug muffins made with sorghum flour and fava bean protein. All of the products are gluten-free.

Further showing its commitment to the bar category, PepsiCo this month selected IQ Bar as one of the 10 inaugural start-ups to participate in its first collaborative accelerator program in North America, the Nutrition Greenhouse program. IQ Bar claims to be the first nutrition bar built for the brain, noting its products are “high-fat, low-carb and packed with six brain-functional nutrients.”

Strength in the bar category also is evident in the activities of Hearthside Food Solutions, Downers Grove, Ill. The largest independent bakery in the United States, Hearthside has been on an expansion kick this year that the company envisions helping it meet consumer demand for, among other things, bars. The company recently acquired a former Kellogg Co. baking plant in Seelyville, Ind.

“The Seelyville acquisition is about future growth,” said Richard G. Scalise, chairman and chief executive officer of Hearthside. “The facility will enable our nutrition bar and bakery business to continue to serve our customers’ expanding needs.”

Earlier, Hearthside doubled production capacity of a nutritional bar formulation and production facility in Boise, Idaho.

Clif Bar & Co., which leads the nutrition and health bar category with sales exceeding $805 million, this past summer introduced three new products, including Fruit Smoothie Filled Energy Bars. Formulated with U.S.D.A.-certified organic and non-G.M.O. ingredients, they feature creamy filling made from a blend of cashew butter and fruit flavors, including strawberry banana, wild blueberry acai and tart cherry berry.

Clif Bar also debuted Clif Bar Sweet & Salty and Clif Energy Granola.

“At Clif, we make craveable food for athletes and everyday adventurers,” said Dan Hickle, vice-president of brand marketing at Clif.

Two other smaller companies capitalizing on the demand for bars are Bonk Breaker and Dang Foods.

Los Angeles-based Bonk Breaker is launching Premium Protein Bars, a line of bars made with collagen protein, grass-fed whey and prebiotic fiber. Each gluten-free, paleo-friendly bar contains 15 grams of protein and fewer than 200 calories. Varieties include cookies and cream, peanut butter dark chocolate chip and double fudge brownie.

Meanwhile, Berkeley, Calif.-based coconut chip maker Dang Foods is debuting a new range of plant-based bars, featuring almond butter, cocoa butter, coconut, pea protein, sunflower seeds and chia seeds. The products were formulated for the trendy high-fat, low-carb ketogenic diet. Flavors include almond vanilla, lemon matcha and chocolate sea salt.

“Dang’s keto-friendly lightly salted coconut chips are the fastest growing item within the portfolio due to their high-fat, low-carb macronutrient profile,” said Vincent Kitirattragarn, founder of Dang Foods. “Keto is on fire right now, garnering more interest than paleo and Whole30 because the benefits are clear: mental acuity, sustained energy and reduced appetite. We did the research and couldn’t find good-tasting keto snacks, so we decided to make Dang Bar using whole ingredients.”

Portion control was on the mind of Kind Healthy Snacks, which earlier this month introduced Kind Minis, a 100-calorie or less snack that the company said fills a need “for people seeking on-the-go snacks that not only taste good also offer balanced nutrition.”

Kind said the new Kind Minis have a nutrient-dense first ingredient. Three bars feature almonds as the main ingredient, while two feature peanuts and one leads with cashews. Select bars also contain fruits, such as cranberries and cherries. Flavors include dark chocolate nuts and sea salt; caramel almond and sea salt; peanut butter dark chocolate; dark chocolate cherry cashew; salted caramel and dark chocolate nut; and dark chocolate almond and coconut.