The Official Aminogen Blog

Sticks and Stones

Can inadequate protein hurt your bones?

 

 

About six years ago, researchers made the case that protein was essential for bone health. They pointed out that increased protein in the diet was associated with increased bone mineral mass and a reduced risk of osteoporotic fractures.

The more lean muscle mass you have, the better your bone mineral content tends to be, too. But it's more than just a correlation. Dietary protein promotes IGF-1, which stimulates bone growth. Authors of the 2005 review concluded that dietary protein was just as important for healthy bone as calcium or vitamin D.

This year, a literature review of the most recent findings also concludes that protein may contribute to bone health via IGF-1, as well as through enhanced calcium absorption and by increasing lean muscle. They conclude with pretty strong words:

"Recent epidemiological, isotopic and meta-analysis studies suggest that dietary protein works synergistically with calcium to improve calcium retention and bone metabolism. The recommendation to intentionally restrict dietary protein to improve bone health is unwarranted, and potentially even dangerous to those individuals who consume inadequate protein."

 

Who is not consuming enough protein?

 

 We know certain populations are at risk, and others argue certain situations may warrant an increased protein intake. But the recently updated DRI's did not increase protein recommendations, and changes to your diet should never be made without consulting your physician.

 

 

Then what does this review tell us, exactly?

 

 

I think this is a great update on the topic, and something important to keep in mind as we age. What it tells us is that dietary protein is important for a number of reasons above and beyond what typically comes to mind (that goes for muscles to)- so we should factor that in when selecting our protein.

Remember, bones have some interesting, newly discovered functionsof their own too. For women who are approaching or have already experienced menopause, protecting bone growth and density is also a priority.

It seems that aging can take it's toll on bone health for both genders.  Knowing that protein intake is an important part of the bone health equation may be the first step in fighting back.

Protein and Testosterone: What's the Connection?

A surprising new study  reports that in men, the skeletal system is involved in testosterone production.

Osteocalcin

It turns out that osteoblasts, bone cells that generate new bone tissue, also produce a hormone called osteocalcin. And osteocalcin, the researchers found, seems to promote testosterone production. The surface of testosterone-producing Leydig cells of the testicle have osteocalcin receptors, and testosterone production in these cells seems to be upregulated or enhanced by the presence of osteocalcin (see diagram).

When scientists injected osteocalcin into mice, testosterone levels increased accordingly.  Mice with low levels of osteocalcin were found to have low levels of testosterone, low sperm counts, and poor rates of reproduction.

While it's been known for some time that sex hormones like estrogen and testosterone can affect bone growth, there wasn't any research on the influence of bone on sex hormone levels. Bones were thought to be the product of metabolism (growth, calcification, etc) rather than producers.

Bone hormone osteocalcin was discovered in 1975 (Hauschka Laboratory of Boston's Children's Hospital). Just a few years ago, in 2007, osteocalcin was found to increase insulin sensitivity and secretion, help to control glucose levels and bodyweight.

Protein, Bone Health and Testosterone

So how does protein fit into the osteocalcin-testosterone equation?

A high protein diet has been shown, in animals, to increase bone mineral content. Human studies have shown that a high protein diet improved recovery from hip fractures. Researchers explain that protein stimulates human growth factor, which in turn promotes bone growth. A 2004 study in the Journal of Endocrinology and Metabolism confirmed that a diet high in protein and low in carbohydrates increased bone growth factor IGF-1in both men and women.*

So what is good for the bones - like protein seems to be- may be good for men's testosterone levels too.

*Interestingly, although the lower estrogen levels women experience after menopause is associated with bone loss, researchers have not yet found evidence of the reverse.  There is no documented effect at this time of osteocalcin on women's estrogen levels or fertility, although future research may prove otherwise. It would make sense, given that low estrogen-osteoporosis connection, but remains to be proven.  

The Shin Bone's Connected to the...

Calf muscle?

Good Aminogen blog readers will already know that Aminogen triples the rate of protein absorption and supports lean muscle. But where is the connection with bone health? That seems to be this week's theme.

Once again bone strength has been linked with muscle mass.  We reported on how a high protein diet was shown to improve bone mineral content and that the lack leg muscle strength has been associated with knee osteoporosis and hip fracture risk.

Now, take a look at this article from the New York Times describing how increasing calf muscle size and strength can reduce the risk of stress fractures.

You can read the complete study in the Official Journal of the the American College of Sports Medicine.

Weak in the Knees

According to the CDC, almost half of all American adults may develop "symptomatic knee osteoarthritis," a painful condition responsible for a good share of today's knee replacement surgeries.  In fact, the CDC reports a 58% increase in the rate of knee replacements in the U.S. between 2000 and 2006.

Now The American Journal of Sports Medicine has published a study suggesting weak quads and hamstrings may be linked to "runner's knee."  Also called patellofemoral pain syndrome, runner's knee is common among runners and older adults - and can lead to knee osteoarthritis.

It seems that since weakened quads and hamstrings may not support and protect the knee the way they should during the movement and impact of exercise, more pressure is put on the bone and cartilage of the knee.

So don't be weak-kneed.  Read the Aminogen Blog's previous coverage on muscle and knee pain, and more about the importance of muscle in injury prevention and overall health. Read more on Aminogen for runners here and here.

You can also check out ExRx's descriptions and helpful video animations of quadriceps and hamstring-strengthening exercises.

High Protein Diet and Bone Health

A study published in the Journal of Nutrition reports that animals fed a high protein diet had reduced body fat while increasing mineral bone content.

The American Journal of Clinical Nutrition has also reported studies in humans concluding that protein may actually have an overall positive effect on bone health.

Lean Muscle and Bone Health

Researchers have found that the amount of lean muscle you have strongly correlates with your bone density.

 

In a study published in the July issue of the Journal of Clinical Endocrinology and Metabolism, researchers reported that the more lean muscle a man had, the better his bone density.  Conversely, the more body fat a man had, the weaker his bones tended to be.

We know that maintaining lean muscle mass is important for a number of reasons.   Muscle  functions differently than fat, and is crucial for proper immune function and metabolism.

Lean muscle loss is also associated with other health issues, like osteoporosis. Studies like this one affirm just how important lean muscle mass is for bone health.

 

So how does your muscle measure up?

  

While using the body mass index can give a general idea of norms for weight and height, its simplified calculations of muscle and bone mass can create an inaccurate picture of actual body composition.  For example, someone with a good deal of healthy muscle mass and  low body fat could be inappropriately categorized as overweight.

If you are serious about building muscle and maintaining a healthy body composition, you may want to have your lean muscle measured.

Check out CNN's article describing some of your options for doing this.  Your gym may offer offer a body fat reading using calipers, for example. 

The most accurate method is a low-dose x-ray procedure known as a Dexa Scan - something to ask your doctor about!  While these scans require more time and money than a caliper reading, they can measure bone mass and lean muscle mass quite reliably.