Does It Matter If Protein Is From Animals or Plants for Bone Health?

Both animal and plant sources of protein appear to be OK for bone health. A new systematic review and meta-analysis from the National Osteoporosis Foundation found that plant protein from soy and animal protein from dairy and other sources did not negatively impact bone health in healthy adults.

This is likely good news for people who eat and enjoy a balanced diet that includes a variety of both plant and animal proteins.

In a recent meta-analysis of seven clinical trials, researchers compared the effect of isolated soy protein (plant protein) with animal protein (dairy, egg or a combination of animal proteins) on bone mineral density (BMD), bone mineral content and markers of bone formation and breakdown.

Selected trials either examined the effects of animal and plant protein intake on BMD of the total body, total hip, lumbar spine, femoral neck or total body bone mineral content (BMC) for at least a year or compared selected markers of bone formation and breakdown for at least six months. Results of the systematic review showed no difference in BMD or BMC outcomes or markers of bone turnover between the soy and animal protein groups (limited strength of evidence).

Most of the clinical studies examined in this systematic review included dairy protein, providing evidence that animal protein from dairy does not differ from plant protein from soy in its impact on bone health. In addition to high-quality protein, milk, yogurt and cheese contribute calcium and other nutrients that help support bone health.

Osteoporosis and low bone mass affect an estimated 54 million Americans over the age of 50. Getting adequate calcium and vitamin D, in addition to physical activity, helps build bone mass during youth, one strategy associated with reduced risk of bone diseases like osteoporosis later in life.

The relationship between dietary protein and bone health has been a topic of debate. Some studies have hypothesized that some sources of protein, especially meat and dairy foods, can increase bone breakdown by increasing urinary calcium excretion. This systematic review and meta-analysis furthers our understanding of the relationship between dietary protein and bone health by showing that protein source does not appear to impact protein’s effect on bone health. I address this topic further here.