August 28, 2010 · 7:09 AM

High-Protein Diets Harmful to Bones? Nah!

Contrary to accepted wisdom, high  protein intake does not seem to be harmful to mineralization of bone, according to Seattle-based researchers reporting in the American Journal of Clinical Nutriton.  Mineralization of bone is important because higher bone mineral content generally translates to lower risk of fractures.

A consistent criticism of low-carbohydrate diets in the past is that they are detrimental to bone health.  How so?  If you reduce carb consumption, you have to replace at least some of the calories with either fat or protein.  Some low-carb diets lean towards higher protein content, others towards higher fat, still others increase both fat and protein.  The building blocks of proteins are amino acids, and some amino acids are acidic.  Acid-rich biochemical states may promote removal of calcium from bone and, ultimately, loss of that calcium in urine.  The calcium-poor bones are more prone to fracture.

If that theory is correct, women eating greater amounts of protein should demonstrate lower bone mineralization.  [The primary bone minerals are calcium and phosphorus.] 

ResearchBlogging.orgInvestigators tested the theory in 560 women aged 14 to 40 by measuring bone mineral density (via DEXA scans) over two or three years and monitoring food consumption via yearly questionnaires.  This was an observational study, not interventional.

They found that bone mineral density had nothing to do with protein consumption.  Higher protein intake was not associated with lower bone density.

Women in the low-protein group ate 52 g of protein daily, compared to 63 g in the medium group and 77 g in the high-protein tertile.  As best I can tell, the low-protein third of participants ate 12% of total calories as protein, compared to 20% in the high-protein third.  [Study authors could have put this in the appropriate table, but, mysteriously, opted against that.]

Caveats

We can’t tell from this study whether these findings apply to protein intakes outside this range, to men, or to women older than 40.  To their credit, the study authors review much of the pertinent literature and note that research in this area produces results all over the map.  To me, this suggests that the association between dietary protein and bone mineralization in the general population is weak, if not nonexistent.

Bottom Line

Looks like you can stop worrying so much about hurting your bones if you’re on a low-carb, high-protein diet.

Steve Parker, M.D.

Reference: Beasley, J., Ichikawa, L., Ange, B., Spangler, L., LaCroix, A., Ott, S., & Scholes, D. (2010). Is protein intake associated with bone mineral density in young women? American Journal of Clinical Nutrition, 91 (5), 1311-1316 DOI: 10.3945/ajcn.2009.28728

 

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August 25, 2010 · 2:00 AM

Do Calcium Supplements Cause Heart Attacks?

They might, if you’re a woman over 50 taking over 500 mg elemental calcium daily without a vitamin D supplement.

Details are at my recent Self/NutritionData Heart Health Blog post.

Steve Parker, M.D.

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August 24, 2010 · 2:53 AM

“Advanced Mediterranean Diet” Has Gone Green

The Advanced Mediterranean DietMy 2007 book, The Advanced Mediterranean Diet: Lose Weight, Feel Better, Live Longer is now available in PDF format for $9.95 USD.  It’s not a low-carb diet book, but a calorie-restricted, balanced diet incorporating the healthy features of the traditional Mediterranean diet.  The physical book is also available from Amazon or CreateSpace. 

My editor and I weren’t thinking globally when we finished the book: measurements are in U.S. customary units.  The average reader can convert to other units with minimal hassle.

Loss of excess weight can be accomplished by measuring either carb grams or calories.  If you can handle monitoring your calorie consumption—and I make it as easy as possible in the book—then the Advanced Mediterranean Diet is a good way to go.  Due to the relatively high carbohydrate content of the traditional Mediterranean diet, however, people with diabetes or prediabetes should do better with carb-counting, as in the Low-Carb Mediterranean Diet or Ketogenic Mediterranean Diet.

Either way, I got you covered.

Steve Parker, M.D. 

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August 23, 2010 · 5:22 AM

2002 Atkins Diet at a Glance

Dr. Robert C. Atkins is the modern popularizer of low-carb dieting.  He was neither the first nor only low-carb advocate of the 20th century, but certainly the most influential in modern history in terms of followers.  His Dr. Atkins Diet Revolution was published in 1972 and sold millions of copies. 

Sir Isaac Newton wrote in 1676: “If I have seen further, it is by standing on the shoulders of giants.”  Twentieth century giants for Dr. Atkins include Frank Evans, Blake Donaldson (the original paleo diet guru?), Per Hansen, Alfred Pennington, and John Yudkin.  Most of these were physicians, by the way.  William Banting preceeded them, in the 19th century.

Dr. Atkins New Diet Revolution, published in 2002, was a huge seller then and maintains a respectable sales volume even now.  My impression is that Atkins Nutritionals, Inc., has replaced it with The New Atkins for a New You, which I reviewed last spring.  Enough people still follow DANDR that I need to stay familiar with it.  Here’s my brief summary of the phases.

Induction or Phase 1

  • Limit carbs to 20 g of “net carbs” daily for a minimum of two weeks.
  • “Net carbs” is the total carb count in grams, minus the fiber grams.
  • 3 cups of salad greens daily with olive oil/vingar or lemon juice OR 2 cups of salad greens and one cup of non-starchy cooked vegetables (e.g., broccoli or zucchini).
  • May also eat 3–4 ounces of aged cheese, a handful of olives, and half an avocado daily.

Ongoing Weight Loss (OWL) or Phase 2

  • Deliberate slowing of weight loss.
  • Gradually add back nutrient-rich carbs.
  • Increase net carbs weekly by just 5 g, by eating more veggies, nuts, seeds, even berries (this is where the “carb ladder” comes into play, adding carb groups in a specific order).
  • Some dieters can even add small amounts of beans and fruits other than berries, until weight loss stalls.  At that point, you drop back 5 g net carbs, to your Critical Carbohydrate Level for Losing (CCLL).

Pre-maintenance or Phase 3

  • Begins 5 or 10 pounds before reaching your weight goal.
  • Weight loss slows even more, taking at least 2 months to lose that last 10 pounds.
  • Can now add some starchy veggies like sweet potatoes, peas, whole grains.
  • If weight loss stops before goal, drop back down by 5-10 g net carbs, to your revised CCLL.

Lifetime Maintenance or Phase 4

  • Starts when you’ve been at goal weight for one month.
  • No more junk food, ever.
  • Stay vigilant for excessive carbs.  You may never be able to go back to whole grains or higher-carb fruits and vegetables.

Steve Parker, M.D.

PS: Gary Taubes reviews the history of low-carb diets in his masterpiece, Good Calories, Bad Calories.

Sir Isaac Newton
Head and shoulders portrait of man in black with shoulder-length gray hair, a large sharp nose, and an abstracted gaze

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August 19, 2010 · 11:17 PM

Salmonella Is IN the Eggs

The American Council for Science and Health published a brief report on the current massive commercial egg recall in the U.S.  Read it for the CDC’s tips on avoiding Salmonella infection.

I had thought the Salmonella germs were simply on the surface of the eggs.  Not so, according to ACSH: the hens’ ovaries are contaminated, so the germ ends up in the egg white, yolk, and shell.

Steve Parker, M.D.

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August 19, 2010 · 2:00 AM

Top 50 Blogs About Diabetes

The Health Crazies website listed this blog among “The Top 50 Blogs About Diabetes.”  You may want to check out some of the others listed, and my own blogroll to the right.

Thanks to Health Crazies.

Steve Parker, M.D.

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August 18, 2010 · 7:53 AM

Whole Grains Lower Blood Pressure: So What?

The American Journal of Clinical Nutrition earlier this month published a research report on whole grain consumption and various cardiovascular disease risk factors.  U.K. investigators compared the effects of refined grains versus whole grains in healthy middle-aged adults.  The strongest finding was that three servings a day of whole grains—wheat and oats in this instance—reduced systolic blood pressure by 5 mmHg. 

The investigators suggest this BP lowering may be responsible for the reduced risk of heart attack and stroke associated with whole grain consumption in observational studies.

Additional details are at my Self/NutritionData Heart Health Blog post of August 17, 2010.  The researchers noted a three or four percent reduction in LDL cholesterol (“bad cholesterol”) in study participants eating refined grains, yet , mysteriously, had nothing to say about that.

Steve Parker, M.D.

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August 16, 2010 · 2:42 PM

High Carbohydrate Eating Increases Risk of Diabetes

ResearchBlogging.orgThe American Journal of Clinical Nutrition reported earlier this month that high consumption of carbohydrates, high-glycemic-index eating, and high-glycemic-load eating increases the risk of developing diabetes.  High fiber consumption, on the other hand, seems to protect against diabetes. 

The article abstract doesn’t mention type 1 versus type 2 diabetes, but it’s probably type 2, the most common kind.

The observational reseach was done in the Netherlands, but I bet the findings apply to other populations as well.  Australian researchers had established years ago that high-glycemic-index and high-glycemic-load eating is associated with onset of diabetes, at least in women. 

Is high carbohydrate consumption putting too much strain on the pancreas, which produces the insulin needed to process the carbs?

Steve Parker, M.D.

Reference:  Sluijs I, van der Schouw YT, van der A DL, Spijkerman AM, Hu FB, Grobbee DE, & Beulens JW (2010). Carbohydrate quantity and quality and risk of type 2 diabetes in the European Prospective Investigation into Cancer and Nutrition-Netherlands (EPIC-NL) study. The American journal of clinical nutrition PMID: 20685945

1,2,3

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August 13, 2010 · 8:16 AM

Is a Low-Carb Diet Safe For Obese Adolescents?

High-protein, low-carbohydrate diets are safe and effective for severely obese adolescent, according to University of Colorado researchers.

Childhood obesity in the U.S. tripled from the early 1980s to 2000, ending with a 17% obesity rate.  Overweight and obesity together describe 32% of U.S. children.  Some experts believe this generation of kids will be the first in U.S. history to suffer a decline in life expectancy, related to obesity.

Colorado researchers wondered if a low-carb, high-protein diet is a reasonable treatment option.  Why high protein?  It’s an effort to preserve lean body mass (e.g., muscle). 

ResearchBlogging.orgThey randomized 46 adoloscents (age 12–18) to either a high-protein, low-carb diet (HPLC diet) or a calorie-restricted low-fat diet to be followed for 13 weeks.  HPLC dieters could eat unlimited calories as long as they attempted to keep carb consumption to 20 g/day or less.  Low-fat dieters were to choose lean protein sources, aiming daily for 2 to 2.5 grams of protein per kilogram of ideal body weight.  Study participants underwent blood analysis and body compositon analysis by dual x-ray absorptiometry.  These kids weighed an average of 108 kg (238 lb) and average body mass index was 39. 

Analysis of food diaries showed the following:

  • Average caloric intake was 1300-1450/day, toward the lower end for the HPLC dieters
  • Energy composition of the HPLC diet: 32% from protien, 11% from carb, 57% from fat
  • Energy compositon of the LF diet: 21% from protein, 51% from carb, 29% from fat
  • Average daily carb consumption for the HPLCers ended up closer to 40 g (still very low) 

Findings

Both groups lost weight, with the HPLC dieters trending to greater weight loss, but not to a statistically significant degree.  They did, however, show a greater drop in body mass index Z-score, however.  Study authors didn’t bother to explain “body mass index Z-scores,” assuming I would know what that meant.  Average weight in the HPLC group dropped 13 kg (29 lb) compared to 7 kg (15 lb) in the low-fat group.

Total and LDL cholesterol fell in both groups, and insulin resistance improved.  Neither diet had much effect on HDL cholesterol.

As usual, triglycerides fell dramatically in the HPLC dieters.

Nearly 40% of the kids—about the same number in both groups—dropped out before finishing the 13 weeks.

The HPLC group did not see any particular preservation of lean body mass, and actually seemed to lose a bit more than the low-fat group.

There were no serious adverse effects in either group. 

Surprisingly, satiety and hunger scores were the same in both groups.  [Low-carb, ketogenic diets have a reputation for satiation and hunger suppression.]

My Comments

This is a small short-term study with a large drop-out rate; we must consider it a pilot study.  That’s why I’m not as enthusiastic about it as the researchers.  Nevertheless, it does indeed suggest that high-protein, low-carb diets are indeed safe and effective in obese adolescents.  It’s a start.   

Steve Parker, M.D.

Reference: Krebs, N., Gao, D., Gralla, J., Collins, J., & Johnson, S. (2010). Efficacy and Safety of a High Protein, Low Carbohydrate Diet for Weight Loss in Severely Obese Adolescents The Journal of Pediatrics, 157 (2), 252-258 DOI: 10.1016/j.jpeds.2010.02.010

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