Beyond The Headlines – What Is A High-Protein Diet?
G. Douglas Andersen, DC, DACBSP, CCN
The other day a patient entered my office and complained about protein. She had just heard a report on the radio indicating that a high-protein diet could contribute to osteoporosis. I explained to her how protein can help increase or decrease bone density (see Dynamic Chiropractic, volume 20, number 23, Protein, Calcium, and Bone Density, Part 2: The Protein-Calcium Paradox).
This month we will focus on a very common phrase – "high-protein diet."
Whenever you hear high-protein diet on the radio or television, it is rarely accompanied by a definition or description. Jump on the Internet and search high-protein diets and you will find the vast majority of top sites, (both in favor or against high-protein diets) rarely inform the reader what they mean by high-protein diet. There are scholarly publications that show high-protein diets:
- Promote weight gain1
- Promote weight loss2,7
- Increase bone density3,4
- Decrease bone density5,6
- Are safe for the kidneys4
- May harm the kidneys5,6
- Cause weight loss by water loss5,6
- Cause weight loss by fat loss2,4,7
- Elevate blood lipids4
- Reduce blood lipids2,7
- Are safe for the liver4
- May harm the liver5,6
- Increase the risk of heart disease5,6,8
- Decrease the risk of heart disease2,4,8
- Increase the risk of some types of cancer5,10
- Decrease the risk of some types of cancer9,11
The truth is, all of these seemingly contradictory statements may be correct depending on how both "high-protein" and "high-protein diet" are defined.
What is high protein?
There are 3 ways of defining a high protein intake:
- The protein-to-body weight ratio. See Table 1. The adult RDA is .8 grams per kilogram (2.2 pounds) of bodyweight per day (gr/ kg/ bw/ d). 1.5 gr/kg/bw/d is normally considered a diet high protein.
- Percentage of total calories. A diet containing 25% of the calories from protein is normally considered the low end of a high-protein diet. When thirty percent or more of daily calories come from proteins, most nutrition professionals classify this as a high protein diet.
- Total daily protein grams. 300 grams of protein a day is a very high amount for all but a select few (such as a 350 pound professional athlete).
What is a high-protein diet?
In addition to the amount of protein, the source (animal or vegetable)and the type (whole food or processed) of protein(s) must be determined. Consideration for 'diet' must also include daily caloric intake and how it breaks down: the amount of fat (saturated and unsaturated), fatty acids, (Omega 3 – 6 – 9) carbohydrate, (simple and complex) and fiber (soluable and insoluable). Each of the above can contribute to how a so-called high protein diet will affect human physiology. The size, gender, activity and age of a person or persons in the study can further influence results and therefore should be known before the data is applied.
In conclusion high protein diet headlines and sound bites seldom provide the details needed to insure that any personal health change they provoke will be beneficial for the individual.
||Grams of Protein per Kilogram of Body Weight
Women over 15
Men over 18
Males age 15-18
Children ages 7-14
Pregnancy and Lactation
Children ages 1-6
||1.2 to 1.4
||1.4 to 1.8
||1.5 to 2.0
|1.5 – 2.0
1 Grillenberger, M., Neumann, C.G., Murphy, S.P., et al. Food Supplements have a Positive Impact on Weight Gain and the Addition of Animal Source Foods Increases Lean Body Mass of Kenyan Schoochildren. J. Nutr. 2003; 133: 3957S – 3964S.
2 Parker, B. Noakes, M., Luscombe, N.. et al. Effects of a High-protein, High-monostaturated Fat Weight Loss Diet on Glycemic Control and Lipid Levels in Type 2 Diabetes. Diabetes Care. 2002; 25: 425-430.
3 Dawson-Huges, B., Harris, S .S. Calcium Intake Influences the Association of Protein with Rates of Boneloss in Elderly Men and Women. Am J Clin Nutr. 2002; 75: 773-779.
4 Manninen, A.H. High Protein Weight Loss Diets and Purported Adverse Effects: Where is the Evidence? Sp. Nutr. Rev. J. 2004; 1(1): 45-51.
5 Denke, M.A. Metabolic Effects of High-protein, Low-carbohydrate Diets. Am. J. Cardiol. 2001; 88(1): 59-61.
6 St. Jeor, S.T., Howard, B.V., Prewitt, T. E., et al. Dietary Protein and Wieght Reduction. Circulation. 2001; 104(15): 1869-1874.
7 Layman, D.K., Boileau, R.A., Erickson, D.J., et al. A Reduced Ratio of Dietary Carbohydrates to Protein Improves Body Compostion and Blood Lipid Profiles during Weight Loss in Adult Women. J. Nutr. 2003; 133: 411-417.
8 Vega-Lopez, S., Lichtenstein, A.H. Dietary Protein Type and Cardiovascular Disease Risk Factors. Prev. Cardiol. 2005; 8(1): 31-40.
9 Shu, X.O., Jin, F., Dai, Q., et al. Soyfood Intake during Adolescence and Subsequent Risk of Breast Cancer among Chinese Women. Cancer Epidemiology Biomarkers & Prevention. 2001; 10: 483-488.
10 Norat, T., Lukanova, A., Farrari, P., et al. Meat Consumption and Colorectal Cancer Risk: Dose-response Meta-analusis of Epidemiological Studies. Int. J. Cancer. 2002; 98(2): 241-256.
11 Sato, Y., Nakaya, N., Kuriyama, S., Nishino, Y., Ysubuno, Y, Tsuji, I. Meat Consumption and Risk of Colorectal Cancer in Japan: The Miyagi Cohort Study. Eur. J. Cancer Prev. 2006; 15(3): 211-218.
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