Not all proteins are equal when it comes to the health of dieters eating low-carbohydrate, high-protein diets.

Animal-based proteins and fats are associated with increased mortality rates, including increased cardiovascular mortality and increased cancer mortality, a new study published in the Annals of Internal Medicine concludes. But low-carbohydrate, high-protein diets composed mostly of plant-based proteins and fats were associated with lower mortality rates overall and lower cardiovascular mortality rates.

The study followed more than 85,000 women and 44,500 men for a period of 20 to 26 years. All the study participants were without heart disease, cancer, or diabetes. To reach their conclusion, the study authors accounted for lifestyle factors such as smoking, exercise, multivitamin use, and alcohol intake. The study participants were all health professionals who filled out regular questionnaires about their food intake over the long follow-up period. The study authors acknowledged that while the large sample of participants was a strength of the study, its participant pool of all health care professionals was a limitation because it was not representative of the larger population.

The benefits of eating a low-carbohydrate, plant-based diet

Results of the study confirmed a "direct association" between animal-based low-carbohydrate food intake in men and increased cancer deaths, particularly from colorectal and lung cancer. That association aligns with previous studies that have confirmed a link between red meat, processed meat, and those two types of cancers. The study also found that men and women who ate diets heavy in animal-based proteins had higher averages BMIs and were more likely to smoke. Yet men and women who ate more plant or vegetable-based proteins and fats ate more whole grains and tended to drink more alcohol.

"The protein you get from combining rice and beans is the same quality as what you get from eggs and steak. You just don't get all the other stuff that's bad for you, " says Dr. Dean Ornish, founder and president, Preventive Medicine Research Institute, who is not affiliated with this study.

"This is the diet that I've been advocating for for 30 years."

The study authors say the low-carb, high-protein diets followed by its participants "were not designed to mimic any particular versions of low-carbohydrate diets available in the popular literature." Yet when most people think of a high-protein eating plan, they think of the Atkins diet. Atkins says nothing about its eating plans can be deduced by this study. In a statement to CNN, the company says, "Major clinical research has demonstrated the health benefits of low-carb diets," including several dozen articles on the Atkins protocols that "demonstrate positive results in terms of weight loss, as well as improvements in lipid profiles, reduced inflammation and better blood sugar control."

Dieters interested in eating more plant and vegetable-based proteins should consider adding tofu, beans, legumes, nuts, and seeds in to their diet. Sunflower oil, olive oil, canola oil, soy oil, and peanut oil are also great sources of plant-based fats.

"Plant-based diets – fruits, vegetables, whole grains, a little fish, soy products, legumes – you want to eat more towards that end of the spectrum, not exclusively vegetarian," says Ornish.