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Wednesday, May 24, 2006

Low-Carb Bone Loss Is A Myth, Study Shows

Even as the media and health experts continue to mischaracterize and maliciously taint livin' la vida low-carb as an unhealthy nutritional approach for a myriad of reasons, scientific research keeps coming to low-carb's defense with evidence to the contrary.

In a new study released in the May 23, 2006 online version of the scientific journal Osteoporosis International, researchers debunk the popular myth that low-carb diets deplete bone growth because of increased acidity and leads to osteoporosis.

“That's not what our study found," remarked Dr. John D. Carter, assistant professor in the Division of Rheumatology at the University of South Florida College of Medicine.

In fact, because of this common belief about low-carb diets, Dr. Carter wanted to see for himself what kind of effect a low-carbohydrate diet would have on bone turnover since the assumption by medical professionals has been that the ketogenic state brought on by an increased consumption of protein and fat would make bone health get worse in human subjects.

Dr. Carter observed a 15-person low-carb group as well as 15-person control group for the 3-month study. Members of the low-carb group were to eat less than 20g carbs daily for the first month and then less than 40g carbs in the second and third months. Of course, the control group was given no conditions regarding their diet and could eat as they normally would.

The following includes some advanced medical jargon that may be difficult to follow, but stay with me on this. Researchers looked at the urinary N-telopeptide (referred to as UNTx), a clear marker of bone resorption, at the conclusion of the 3-month study and found the low-carb diet group increased their mean levels by 1.6 compared with 1.9 in the control subjects. After just one month, the mean UNTx levels decreased by 2.2 in the low-carb group compared with 3.1 in the control group.

As for the bone-specific alkaline phosphatase (known as BSAP), another clear marker observed regarding bone health, after one month the low-carb group saw a decrease of 0.53 while the control group increased by 0.34.

But the bone turnover ratio (BSAP/UNTx) after one month into the study while the low-carb group was still on 20g carbohydrates per day saw an increase in that group by 0.08 compared to 0.05 in the control group.

Not at all surprising is the fact that the low-carb diet group lost "significantly more weight" with a 6.39kg weight loss compared with just 1.05kg for the control at the end of the three months.

The primary end point was urinary N-telopeptide (UNTx) at 3 months. Secondary end points included UNTx at 1 month, bone-specific alkaline phosphatase (BSAP) at 1 month, bone turnover ratio (BSAP/UNTx) at 1 month, and weight loss.

Dr. Carter commented that while there was a measurable difference in the weight loss of the low-carb diet group compared with the control group, the low-carb diet did not seem to increase the bone turnover markers compared with the control at any point during the study. Additionally, there was "no significant change in the bone turnover ratio" either.

“Patients on the low carbohydrate diet did lose weight, but the diet did not appear to compromise bone integrity or lead to bone loss," Dr. Carter concluded.

In fact, he stated how shocked he was to get the results that he did from his study.

"People on low carbohydrate diets absorb less calcium through the gut and excrete more calcium in the urine, so you'd expect they would be leaching their bones," Dr. Carter exclaimed, although the doctor in him couldn't resist cautioning people avoid a "strict" low-carb diet over the long-term.

I guess this new scientific evidence supporting the FACT that low-carb does not promote poor bone health means that Jackie Parrington with the National Osteoporosis Society owes those of us who are livin' la vida low-carb an apology for leading to an increase in broken bones due to a decrease in bone turnover. WRONG-O!

Or how about "Dr. David" who warned everyone that people on low-carb have calcium that "leaches out of your bones?" DOUBLE WRONG-O!

Actually, Dr. Carter's study coincides quite nicely with another study that released in July 2005 by Dr. John Briffa which found that higher protein intake and lower carbohydrate consumption is generally associated with improved bone density.

Just as I have blogged about regarding the future of low-carb, scientific studies like this one will continue to validate this incredibly healthy lifestyle change that me and millions of people like me have chosen to lose weight, keep the weight off, and live a long and healthy life with strong bones to boot!

You can e-mail Dr. John D. Carter to thank him for his research at jocarter@hsc.usf.edu.

5-26-06 UPDATE: Dr. Carter responded to my blog post today.

Hi Jimmy,

Congratulations on your weight loss and previous publication. Human pathophysiology is incredibly complex. While preliminary data would suggest that a strict low-carb diet would compromise bone quality, our study suggests otherwise. A previous study did suggest increased bone turnover after 4 days of a high protein diet in young healthy females. This contradicts our findings. It is my feeling that there is an initial increase in bone turnover for the first few days to weeks and then bone somehow regulates itself and turnover returns to normal (sometime before 1 month). This would mirror the previous data regarding cholesterol. Keep up the good work! All the best to you and your readers.


THANKS, Dr. Carter, and keep up the great research you are doing on livin' la vida low-carb!

2 Comments:

Blogger Science4u1959 said...

The "prudent" treatment for prevention of osteoporosis is supplementation of calcium, usually with low-fat, calcium fortified milk. This "wisdom" is actually counterproductive. In fact many studies have shown that calcium supplementation may actually make the condition worse. This is not surprising as a lack of calcium causes osteomalacia and not osteoporosis - a common misconception. Osteoporosis is caused by a weakening of the protein matrix of the bones, and the best preventative measure for this is a high-protein diet, not calcium supplementation.

So yes, high-protein diets increase calcium excretion to some degree - but at the same time they increase calcium absorption to a significantly greater degree! This of course, is why the overwhelming majority of epidemiological studies show low bone density to be more closely associated with LOW protein intakes, and vice-versa for high protein intakes.

A good reference for this:

Kerstetter, et al. Low protein intake: The impact on calcium and bone homeostasis in humans. Journal of Nutrition, 2003; 133: 855S-861S.

5/25/2006 11:13 AM  
Blogger Newbirth said...

That would actually made sense about initial increase bone loss eventually stabalizing. The body strives for homeostatsis so it will respond to a change in diet by adjusting things, such as turning excess protein in glucose to fuel itself.

I take a good calcium supplement too, with a multi-vitamin at the same time to increase absorbtion of the calcium.

5/28/2006 10:30 PM  

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