It seems that everyone is trying to eat more protein these days. Higher protein diets can help you manage your appetite, preserve muscle mass, and even help with weight loss. But what about your bones? Is there a hidden cost to higher protein diets?
When you increase your protein intake—especially from animal sources—the amount of calcium in your urine goes up. The assumption has always been that this urinary calcium was being taken from the bones in order to buffer the acid residue that remains after digestion of meat and other animal products.
Obviously, if something you are eating is regularly causing the calcium to leach out of your bones and into the toilet, over time this is going to be very bad news for your bones. However, this is not at all what is happening.
When you increase your protein intake, your body starts absorbing more a lot calcium from your food. It turns out that almost all of the extra calcium in the urine when you increase your protein intake is due to increased intestinal absorption of calcium. Very little is coming from your bones. And this probably explains why people with higher protein diets do not, in fact, have higher fracture rates or lower bone mineral density.
Higher Protein Diets May Strengthen Bones
Just this month, a group of researchers from Harvard published data from more than 100,000 men and women that were followed over the course of more than 30 years. Among the men, the risk of fracture went down as protein intake (from any source) went up. Among the women, total protein intake didn’t seem to affect risk positively or negatively. But higher intakes of plant-based and dairy proteins reduced the risk of hip fracture. Earlier this year, researchers assessed a group of 750 women in their 60s and found that higher protein intakes were associated with increased bone strength.
And most recently, researchers writing in the American Journal of Clinical Nutrition compiled the results from 36 different studies looking at the effect of protein intake on bone health. This meta-analysis also found no evidence that higher protein diets endanger bones and some evidence that higher protein diets actually protect against bone loss.
Bottom line: A diet that is too low in protein actually appears to be a much bigger threat to your bone health than one that’s higher in protein.
What’s the Right Amount of Protein?
The recommended daily allowance for protein is 50 grams per day. However, there is a growing chorus of scientists calling for increasing that recommendation to 75 or even 100 grams per day in light of recent evidence—especially for people over 50.
The good news is that most Americans are already getting between 75 and 100 grams of protein per day. And you can get more benefit from the protein you eat simply by spreading it out more evenly throughout the day, rather than eating most of it at dinner time.
Healthy Bones Need More than Just Protein
But there are many things besides protein that affect bone health. In addition to adequate protein, healthy bones require a variety of vitamins and minerals, including vitamin D and K, calcium, and magnesium. And that’s why my dietary prescription for healthy bones isn’t just about getting more protein (or calcium) but also encourages eating plenty of vegetables! Also, because vitamin D is not terribly well-distributed in the food supply, a vitamin D supplement may be a good idea.
Exercise also plays an important role in bone health, in two important ways. 1) Strong muscles help maintain strong bones. Strength training exercise with weight machines, stretchy bands, free weights, or even your own body weight helps to maintain muscle strength throughout life. 2) Impact also helps strengthen bones. Walking gives your bones some low impact stimulation, but if you can manage a bit of jogging, jumping, bouncing, or other higher impact activities, so much the better.
Note: The original version of this article appears on QuickandDirtyTips.com. Follow Monica Reinagel on Twitter and Facebook @nutritiondiva.