Protein Matters

January 6, 2012 Written by JP       [Font too small?]

Beef is often included on a short list of foods which are purported to increase the risk of various diseases. Among the health concerns expressed about beef is a supposed correlation between red meat consumption and cardiovascular disease. However, a just published study in the American Journal of Clinical Nutrition begs to differ with this prevalent theory. In the trial, a group of participants with high cholesterol were fed one of four diets for 5 weeks. Those receiving a diet known as BOLD+, comprised of 28% fat, 27% protein and includes 153 grams of beef/day, demonstrated greater improvements in several cardiovascular risk factors than subjects receiving lower beef and protein diets. According to the authors of the study, these findings “provide support for including lean beef in a heart-healthy dietary pattern”.

Before you get too enthusiastic about beef, it’s worth noting that another recent investigation determined that replacing beef with other protein sources may lower stroke risk. An evaluation of over 84,000 women determined that substituting beef with chicken, fish or nuts lowered the relative stroke risk in women by -27%, -17% and -17% respectively. What may be surprising to some is that replacing beef with legumes did not result any significant benefit. In the analysis, low and whole fat dairy products afforded a more modest 10% – 11% reduction in risk.

The importance of adequate protein is also highlighted in three additional publications from the past few months. The first reports that replacing carbohydrates with protein is an effective means of lowering blood sugar, body fat and weight in women with polycystic ovary syndrome or PCOS. The experimental diet in question contained >40% calories from protein and 30% calories from fat. Another trial revealed that a high protein, low calorie diet outperformed a carbohydrate-rich, low calorie diet by reducing fat cell volume and several cardiometabolic indicators in obese adults. Finally, the fear that some have about dietary protein promoting bone density loss also appears to be largely unfounded. The December issue of the journal Clinical Nutrition draws an inverse link between higher protein intake and fracture risk in seniors. In particular, greater consumption of animal protein was associated with a decreased incidence of fractures. This observation held true regardless of calcium intake.

Note: Please check out the “Comments & Updates” section of this blog – at the bottom of the page. You can find the latest research about this topic there!

To learn more about the studies referenced in today’s column, please click on the following links:

Study 1 – Beef in an Optimal Lean Diet Study: Effects on Lipids, Lipoproteins, (link)

Study 2 - Dietary Protein Sources and the Risk of Stroke in Men and Women (link)

Study 3 – Effects of Increased Dietary Protein-to-Carbohydrate Ratios in Women(link)

Study 4 - Differential Effects of Macronutrient Content in 2 Energy-Restricted (link)

Study 5 - Protein Intake and Fracture Risk in Elderly People: A Case-Control Study (link)

Diets Rich in Lean Beef (BOLD+) May Improve Some Cardiovascular Risk Factors

Source: Am J Clin Nutr January 2012 vol. 95 no. 1 9-16 (link)

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Posted in Diet and Weight Loss, Food and Drink, Nutrition

6 Comments & Updates to “Protein Matters”

  1. joanna Says:

    Are there any similar studies where they look at the source of the protein? For instance grass fed beef, or free range chicken compared to the mass produced meat? My understanding is that there is a difference in composition of certain components like omega 3 content which would affect the risks of heart disease (http://www.nutritionj.com/content/9/1/10). The presence of omega 3 in beef, of course does not necessarily translate to better outcomes and so I wondered if that was included in a study to confirm one way or another if that is true.

  2. JP Says:

    Hi Joanna.

    The study in question is pretty narrow in its objective: to see if conventionally raised, lean beef negatively impacts cardiovascular risk factors. Unfortunately, grass fed beef wasn’t used as another means of comparison. Having said that, other studies lead me to believe/suspect that grass fed beef would likely result in even better results.

    http://j.mp/zTVe2g

    Studies evaluating the effects of omega-3 rich eggs have found similar positive findings:

    http://www.ncbi.nlm.nih.gov/pubmed/18991244

    http://www.ncbi.nlm.nih.gov/pubmed/14639800

    I’m unaware of any trials comparing the effects of free range and conventionally raised chicken re: lipid alterations. But, based on the anticipated difference in fatty acids, I think it’s safe to assume that free range chickens are a healthier bet.

    http://ps.fass.org/content/90/7/1600.abstract

    Be well!

    JP

  3. JP Says:

    Update:

    http://ajpendo.physiology.org/content/308/1/E21

    Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults

    To examine whole body protein turnover and muscle protein fractional synthesis rate (MPS) following ingestions of protein in mixed meals at two doses of protein and two intake patterns, 20 healthy older adult subjects (52–75 yr) participated in one of four groups in a randomized clinical trial: a level of protein intake of 0.8 g (1RDA) or 1.5 g·kg−1·day−1 (∼2RDA) with uneven (U: 15/20/65%) or even distribution (E: 33/33/33%) patterns of intake for breakfast, lunch, and dinner over the day (1RDA-U, 1RDA-E, 2RDA-U, or 2RDA-E). Subjects were studied with primed continuous infusions of l-[2H5]phenylalanine and l-[2H2]tyrosine on day 4 following 3 days of diet habituation. Whole body protein kinetics [protein synthesis (PS), breakdown, and net balance (NB)] were expressed as changes from the fasted to the fed states. Positive NB was achieved at both protein levels, but NB was greater in 2RDA vs. 1RDA (94.8 ± 6.0 vs. 58.9 ± 4.9 g protein/750 min; P = 0.0001), without effects of distribution on NB. The greater NB was due to the higher PS with 2RDA vs. 1RDA (15.4 ± 4.8 vs. −18.0 ± 8.4 g protein/750 min; P = 0.0018). Consistent with PS, MPS was greater with 2RDA vs. 1RDA, regardless of distribution patterns. In conclusion, whole body net protein balance was greater with protein intake above recommended dietary allowance (0.8 g protein·kg−1·day−1) in the context of mixed meals, without demonstrated effects of protein intake pattern, primarily through higher rates of protein synthesis at whole body and muscle levels.

    More Info: http://www.sciencedaily.com/releases/2015/01/150130121613.htm

    Be well!

    JP

  4. JP Says:

    Update: Higher protein diets may lower risk of cardiometabolic disease …

    http://jn.nutrition.org/content/145/3/605.abstract

    J Nutr. 2015 Mar;145(3):605-14.

    Higher-Protein Diets Are Associated with Higher HDL Cholesterol and Lower BMI and Waist Circumference in US Adults.

    BACKGROUND: Protein intake above the RDA attenuates cardiometabolic risk in overweight and obese adults during weight loss. However, the cardiometabolic consequences of consuming higher-protein diets in free-living adults have not been determined.

    OBJECTIVE: This study examined usual protein intake [g/kg body weight (BW)] patterns stratified by weight status and their associations with cardiometabolic risk using data from the NHANES, 2001-2010 (n = 23,876 adults ≥19 y of age).

    METHODS: Linear and decile trends for association of usual protein intake with cardiometabolic risk factors including blood pressure, glucose, insulin, cholesterol, and triglycerides were determined with use of models that controlled for age, sex, ethnicity, physical activity, poverty-income ratio, energy intake (kcal/d), carbohydrate (g/kg BW) and total fat (g/kg BW) intake, body mass index (BMI), and waist circumference.

    RESULTS: Usual protein intake varied across deciles from 0.69 ± 0.004 to 1.51 ± 0.009 g/kg BW (means ± SEs). Usual protein intake was inversely associated with BMI (-0.47 kg/m(2) per decile and -4.54 kg/m(2) per g/kg BW) and waist circumference (-0.53 cm per decile and -2.45 cm per g/kg BW), whereas a positive association was observed between protein intake and HDL cholesterol (0.01 mmol/L per decile and 0.14 mmol/L per g/kg BW, P < 0.00125).

    CONCLUSIONS: Americans of all body weights typically consume protein in excess of the RDA. Higher-protein diets are associated with lower BMI and waist circumference and higher HDL cholesterol compared to protein intakes at RDA levels. Our data suggest that Americans who consume dietary protein between 1.0 and 1.5 g/kg BW potentially have a lower risk of developing cardiometabolic disease.

    Be well!

    JP

  5. JP Says:

    Updated 04/18/16:

    http://www.ncbi.nlm.nih.gov/pubmed/27086196

    Clin Nutr. 2016 Apr 7.

    Per meal dose and frequency of protein consumption is associated with lean mass and muscle performance.

    BACKGROUND: It has been hypothesized that for older adults evenly distributing consumption of protein at 30-40 g per meal throughout the day may result in more favorable retention of lean mass and muscular strength. Such a thesis has not, to our knowledge, been tested outside of short-term studies or acute measures of muscle protein synthesis.

    AIMS: To examine whether the number of times an individual consumed a minimum of 30 g of protein at a meal is associated with leg lean mass and knee extensor strength.

    METHODS: Data from the 1999-2002 NHANES were used, with 1081 adults (50-85 y) constituting the analytic sample. A “multiple pass” 24-h dietary interview format was used to collect detailed information about the participants’ dietary intake. Knee extensor strength was assessed objectively using the Kin Com MP dynamometer. Leg lean mass was estimated from whole-body dual-energy X-ray absorptiometry (DXA) scans.

    RESULTS: Participants with 1 vs. 0 (βadjusted = 23.6, p = 0.002) and 2 vs. 0 (βadjusted = 51.1, p = 0.001) meals of ≥30 g protein/meal had greater strength and leg lean mass (1 vs. 0, βadjusted = 1160, p < 0.05 and 2 vs. 0, βadjusted = 2389, p < 0.05). The association of protein frequency with leg lean mass and strength plateaued at ∼45 g protein/meal for those consuming 2 vs. 0 meals above the evaluated protein/meal threshold. However, for those with only 1 meal at or above the evaluated threshold, the response plateaued at 30 g/meal. Leg lean mass mediated the relationship between protein frequency and strength, with the proportion of the total effect mediated being 64%.

    CONCLUSIONS: We found that more frequent consumption of meals containing between 30 and 45 g protein/meal produced the greatest association with leg lean mass and strength. Thus, the consumption of 1-2 daily meals with protein content from 30 to 45 g may be an important strategy for increasing and/or maintaining lean body mass and muscle strength with aging.

    Be well!

    JP

  6. JP Says:

    Updated 02/09/17:

    http://www.nrcresearchpress.com/doi/abs/10.1139/apnm-2016-0292?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed

    Appl Physiol Nutr Metab. 2017 Jan 19.

    EFFECTS OF HIGH PROTEIN INTAKE ON BONE TURNOVER IN LONG-TERM BED REST IN WOMEN.

    PURPOSE: Bed rest (BR) causes bone loss, even in otherwise healthy subjects. Several studies suggest that ambulatory subjects may benefit from high protein intake to stimulate protein synthesis and to maintain muscle mass. However, increasing protein intake above the recommended daily intake without adequate calcium- and potassium intake may increase bone resorption. We hypothesized that a regimen of high protein intake (HiPROT), applied in an isocaloric manner during BR with calcium and potassium intake meeting recommended values, would prevent any effect of BR on bone turnover.

    METHODS: After a 20-day ambulatory adaptation to a controlled environment, 16 women participated in a 60-day, 6° head-down-tilt (HDT) BR and were assigned randomly to one of two groups. Control (CON) subjects (n=8) received 1 g/kg body mass/d dietary protein. HiPROT subjects (n=8) received 1.45 g protein/kg body mass/d plus an additional 0.72 g branched-chain amino acids (BCAA) per day during BR. All subjects received an individually tailored diet (before HDTBR: 1888±98 kcal/d; during HDTBR: 1604±125 kcal/d; after HDTBR: 1900±262 kcal/d), with the CON group’s diet being higher in fat and carbohydrate intake.

    RESULTS: High protein intake exacerbated the BR-induced increase in bone resorption marker C-telopeptide (>30%) (p<0.001) by the end of BR. Bone formation markers were unaffected by BR and high protein intake.

    CONCLUSION: We conclude that high protein intake in BR might exaggerate bone loss. Further long-duration studies are mandatory to show how the positive effect of protein on muscle mass can be maintained without the risk of reducing bone mineral density.

    Be well!

    JP

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