A new analysis comparing 20 protein sources has delivered a result that may surprise shoppers accustomed to looking toward steak, salmon or eggs. Tofu claimed first place after researchers weighed nutrition, affordability, availability and environmental impact.

The BPI Score was introduced in a July paper published in the journal Frontiers in Sustainable Food Systems. University of Cambridge researcher Chris Macdonald and the Better Protein Institute created the scoring system.

Each protein source could receive up to 40 points across two broad categories focused on people and the planet. Tofu finished with 36 out of 40 points, earning the highest marks in both categories.

Beans, chia seeds and quinoa completed the top four positions. At the other end of the ranking, mozzarella, lamb, beef and cheddar were among the foods receiving the lowest scores.

The People Score considered sodium, saturated fat and cholesterol, as well as whether a food contains all nine essential amino acids. It also examined the affordability and availability of each protein source.

The Planet Score assessed greenhouse gas emissions, water pollution, land use and freshwater use. Those measures created especially stark differences between tofu and beef when the foods were compared by the amount needed to supply 100 grams of protein.

Producing 100 grams of protein from tofu was associated with an estimated 0.61 kilograms of greenhouse gas emissions. Producing the same amount of protein from beef was associated with 64.19 kilograms, according to the paper.

The land use comparison was similarly wide. Tofu required about 2 square meters of land to provide 100 grams of protein, while beef required about 211 square meters for the same quantity of protein.

The ranking comes with important limitations. It is an initial scoring system developed by one researcher, rather than a controlled trial or dietary guideline, and it relies on grocery data from the U.K.

The system also does not compare foods in portions of the same size. Instead, it calculates how much of each food would be necessary to deliver 100 grams of protein, which can make practical serving sizes an important consideration.

“While acknowledging the limitations of this first iteration, the score provides a robust foundation for a more nuanced conversation,” Macdonald wrote in the paper. Nutrition and fitness experts likewise urged consumers to examine what the ranking measures before allowing it to shape their diets.

Corry Matthews, a fitness and nutrition expert in California and founder of Strength & Grace Fitness, said shoppers should consider protein quality, serving size and whether they can realistically consume enough of a food to meet their needs. Her examples showed how much protein can vary among ordinary servings.

“For example, three ounces of cooked chicken breast provides roughly 26 grams of protein,” Matthews told Fox News Digital. “A half cup of firm tofu may provide around 10 to 15 grams, depending on the product. Two tablespoons of chia seeds provide only about 4 to 5 grams.”

“That doesn't make chia seeds a bad food ... but I wouldn't rely on them as my primary protein source if my goal were to get 25 to 30 grams of protein at a meal,” Matthews continued. The distinction matters when a highly ranked food supplies relatively little protein in a realistic portion.

Matthews noted that eggs, dairy, fish and lean meats generally provide complete protein and can be concentrated sources of essential amino acids. Tofu is also a complete protein, but she said people relying on proteins from plants may need to pay closer attention to serving sizes and total intake.

Ashley Koff, a registered dietitian in Oregon and founder of The Better Nutrition Program, also emphasized individual needs. “Many people do not digest tofu well at all,” Koff said, adding that people should select protein sources they enjoy and can access.

The ranking therefore offers a broad comparison rather than a universal meal plan. Personal goals, digestion, availability, protein concentration and realistic portions can all affect whether a particular food works for an individual.

“My advice? Don't let a ranking do all your nutritional thinking for you,” Matthews added. “Understand what the ranking measures, then choose foods that support your actual goals.”