The Greek definition of the word protein means “to come first” and so it is appropriate to recognize dietary protein as a primary essential nutrient for human health. Protein plays numerous critical roles in the body and recently we are learning that having enough dietary protein for normal function may not be enough for optimal health. New research and scientific methods indicate that previous protein recommendations known as Recommended Dietary Allowances (RDA), may underestimate the amount of protein needed for long-term optimal health.

QUESTION: What are some key functions of dietary protein related to optimal health?

ANSWER: Of course, protein is essential to develop and maintain muscles and the immune system is said to be only as good as your muscles. Along with calcium and vitamin D, a strong skeleton requires the maintenance of a healthy protein matrix as the backbone structure where minerals can adhere. Protein also helps the body hold onto water and maintain hydration, among many other critical functions.

Q: How much dietary protein is needed for optimal health?

A: Based on newer research by a team at the University of Toronto, protein needs have been underestimated from early childhood throughout aging. Dr. Rajavel Elango, now at the British Columbia Children’s Hospital, stresses that newer research shows that many people can benefit from increasing dietary protein to about 0.7 grams of protein per pound of body weight for adults — about double the RDA recommendation.

Many factors affect how much protein a person should consume. Protein needs are dependent on body weight. Therefore, larger people require more protein. Protein needs increase above normal when calorie intake is low. Research indicates that inadequate dietary protein can increase the urge to consume sweets.

Misconceptions abound about plant protein foods. Plant protein foods do contain all essential amino acids. However, some of the essential amino acids are low, requiring proper combinations of protein foods to efficiently meet needs. Another common myth is that the protein in plant sources is more digestible than animal sources. In fact, it is well established that the digestibility of plant proteins is significantly lower than animal proteins. In general, plant protein sources contain considerably more calories per gram of protein than most animal protein sources. Iron and zinc are not well absorbed from plants and this is now compounded by decreases in iron and zinc levels in staple plant foods due to climate change and higher CO2 levels. Also many plant protein foods contain considerable aluminum and manganese that can become neural toxins when consumed in excess.

Q: Can a person consume too much protein?

A: If a person has chronic kidney problems, then protein intake needs to be limited, otherwise twice the RDA should not be problematic for most.

Alan Titchenal, Ph.D., C.N.S., and Joannie Dobbs, Ph.D., C.N.S., are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. Dobbs also works with University Health Services.