BY L. Lee Coyne Ph.D.
Human dietary protein requirements have long been a point of controversy among nutrition experts, health-care professionals, exercise coaches and health conscious consumers. Frequent advice (some, I believe is seriously outdated) has recommended that:
- We eat too much protein
- High protein diets increase calcium excretion and therefore decrease bone mineral density
- You can "get by" on 8% of calories from protein.
- High protein diets are hard on the kidneys.
A summarized answer to this critique list is:
- Will be answered later in this column
- There is no evidence that protein intakes below 300 grams per day have any negative effect on bone density according to a recently published symposium in the American Journal of Nutrition.
- Who wants to just “get by”? Should we not strive for “Optimal”?
- Again, the American Journal of Nutrition dismissed the kidney damage theory at protein intake levels below 300 grams per day. To put this in perspective, 300 grams of protein = 1200 Calories and that would represent 60 - 70% of daily Calories. Nobody would volunteer to eat that much protein when you consider the appetite control issue of protein.
Over the past 20 years, I have endorsed an eating plan that encourages above average levels of protein consumption. I subscribe to an average of 30% of daily calories (instead of the standard 12-15%) come from low fat compete protein sources. The “adequate” protein intake level would be approximately calculated as 0.8 times pounds of desirable weight. At a desirable weight of 160 pounds X 0.8 = 128 grams of protein per day. If desirable weight is only 120 pounds then adequate protein intake is 96 grams. These recommendations will typically double the current Canada Food Guide recommendations based on 12 - 15% of daily Calories.
Understanding Why More Protein
Adequate protein will:
- Control appetite.
- Control insulin production and release.
- Help to keep you alert (excess carbohydrates put you to sleep.)
- Contribute to building and rebuilding a healthy immune system. Low protein diets create a state of vulnerability to infection.
I am also an advocate of obtaining part of your daily protein calories from high quality soy protein supplements for the following reasons. Protein supplements are:
- Easy to prepare (good for those busy mornings)
- Excellent sources of complete high quality and measurable protein
- Versatile and good tasting. (Can be added to recipes)
- High-density protein to Calorie ratio. (More protein /Calorie)
- Low in fat.
The word “protein” comes from the Greek word (I am starting to sound like the father in the movie “My Big Fat Greek Wedding") “Proteose” that means, “to come first”. Think about these facts:
- When our more primitive ancestors - the Nomads - ran low on protein sources (birds, animals or fish), they moved.
- The original appetizers were shrimp, crab, and liver pate - not white flour buns.
- We tend to categorize or plan meals and restaurants by the protein dishes.
- In 1900 the average calorie intake was 3800 calories per day and 15% of it was protein (= 143 grams per day)
Today the average calorie intake is 1800 calories and only 12% is protein (= 55grams per day)
Recent Evidence Supporting Higher Protein Intakes
Dr. David Jenkins, a Professor of Nutrition at the University of Toronto recently published a study in the American Journal of Clinical Nutrition that demonstrated the protective effects of Soy Protein on lowering cholesterol, blood pressure, and homocysteine and likely reduces the risk of some cancers. This concurred with several recently reported studies with similar goals and results including some that highly recommended the strategic use of soy supplements as an efficient way to consume more soy.
In the April 2002 issue of the American Journal of Clinical Nutrition, Dr. Dawson-Hughes and associates from Tufts University in Boston reported the results of a bone mineral density (BMD) study on 342 subjects all over the age of 65 years. They demonstrated that with adequate levels of Calcium and Vitamin D, higher protein intakes were associated with significant gains in BMD. Within their calcium-supplemented group, bone status was proportionate to protein intake. Those with the lowest protein intake, lost bone and those with the highest intake gained enough bone to significantly reduce fracture rate. They concluded that without adequate protein, calcium supplementation failed to protect the skeleton (even when the calcium intake reached 1350 mg per day.
Dr. Promislow and associates reported a second protein and bone density study in the April 2002 issue of the American Journal of Epidemiology from the University of North Carolina. BMD was measured before and after 572 women and 388 men were observed over a four-year period. They reported a significant positive association between animal protein intake and BMD. For every 15 gram per day increase in protein intake there was a corresponding significant increase in BMD. In contrast, a significant negative association was observed with vegetable protein intake levels. However, there was no distinction of how much of the vegetable protein was in fact high quality or complete.
Did you know that bone is 50% protein and 50% mineral?
The results of several recent studies presented at medical conferences over this past year have demonstrated the effectiveness of the “Atkins” “high protein / high fat “eating plan in reducing weight and improving blood chemistry risk factors. The latest study, conducted by Dr. Eric Westman of Duke University, was presented at the annual meeting of the American Heart Association (AHA). Both the AHA and the Duke University Diet and Fitness Center have long been advocates of the traditional low fat - low calorie approach. Westman studied 120 overweight volunteers randomly assigned to either the Atkins plan or to the AHA step I - low fat diet. The Atkins adherents lost 31 pounds compared to 20 pounds by those on the AHA plan. And the Atkins participants showed better compliance - (they stayed on their plan better). Total cholesterol fell slightly in both groups but the Atkins group had an 11 % increase in HDL (good cholesterol) and a 49% drop in triglycerides. On the AHA diet, HDL was unchanged and triglycerides dropped only 22%.
Hopefully the foregoing provides you with a more positive view on protein and helps you to understand that protein really does matter.
Lee Coyne, Ph.D. is a nutritional consultant, lecturer and author of Fat Won't Make You Fat and the Lean Seekers coaching program. He may be reached at 1-800-668-4042 or by e-mail firstname.lastname@example.org
Copyright Lee Coyne, Ph.D., reprinted with permission.
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