Interesting New Meta Analyses Out on BP and Low Carb. Response from Egg Study

In case you haven’t heard, last week the Cochrane Hypertension Group released some compelling updates on Blood pressure medications (1). But before we get to that, you may be wondering what the heck the Cochrane Collaborative is. While TheFatNurse can’t comment on all nursing schools, during TheFatNurse’s time as a wee little nursing student, one of the buzzwords was Evidence Based Practice in school. As a result, one of the organizations to help increase the use of evidence based practice is the Cochrane collaboration.

The Cochran Collaboration consists of over 28,000 volunteers in more than 100 countries that saw a need to organize the medical literature in a way that was easy to understand and evaluate. The goal is to allow evidence based practice to make its way into the healthcare setting. They go about doing this through systematic reviews of randomized control trials. So what did they findout about hypertension and blood pressure?

The Cochrane group set out to see what the literature showed about individuals with anti hypertension medications and mild hypertension (systolic of 140-159 or diastolic of 90-99) but no prior related issues involving cardiovascular diseases/events. They wanted to examine Randomized Control Trial studies that had at least 1 year duration. Specifically, the outcomes from the literature they were examining were all hypertension related such as coronary heat disease, stroke, mortality, total cardiovascular events and adverse effects from medications causing withdrawals. So what did they conclude? In the author’s own words:

In this review, existing evidence comparing the health outcomes between treated and untreated individuals are summarized. Available data from the limited number of available trials and participants showed no difference between treated and untreated individuals in heart attack, stroke, and death. About 9% of patients treated with drugs discontinued treatment due to adverse effects. Therefore, the benefits and harms of antihypertensive drug therapy in this population need to be investigated by further research.

Pretty interesting. Another new study out last week was a meta analysis on low carb diets (2). Here were the results:

A total of 23 reports, corresponding to 17 clinical investigations, were identified as meeting the pre-specified criteria. Meta-analysis carried out on data obtained in 1,141 obese patients, showed the LCD to be associated with significant decreases in body weight (−7.04 kg [95% CI −7.20/−6.88]), body mass index (−2.09 kg m−2[95% CI −2.15/−2.04]), abdominal circumference (−5.74 cm [95% CI −6.07/−5.41]), systolic blood pressure (−4.81 mm Hg [95% CI −5.33/−4.29]), diastolic blood pressure (−3.10 mm Hg [95% CI −3.45/−2.74]), plasma triglycerides (−29.71 mg dL−1[95% CI −31.99/−27.44]), fasting plasma glucose (−1.05 mg dL−1[95% CI −1.67/−0.44]), glycated haemoglobin (−0.21% [95% CI −0.24/−0.18]), plasma insulin (−2.24 micro IU mL−1[95% CI −2.65/−1.82]) and plasma C-reactive protein, as well as an increase in high-density lipoprotein cholesterol (1.73 mg dL−1[95%CI 1.44/2.01]). Low-density lipoprotein cholesterol and creatinine did not change significantly

Again, very interesting stuff. Also David Spence, the author behind the egg yolk as deadly as cigarette smoking study (as some in the media dubbed it), responded to Nutritionist Zoe Harcombe’s critique of his study in her blog’s comments. Just scroll down until you find it.  It’s a good debate between Dr. Spence and Zoe Harcombe.

Picture by Coldbourne from ClipArt. Creative Commons Attribution-Share Alike 3.0

TheFatNurse hopes this is where the future of research is heading towards where debate can occur openly and freely for people to observe and put in their analysis. What would make this better is if all studies were open to the public and not just the abstracts. For example, the two studies TheFatNurse mentioned are not accessible with TheFatNurse’s university account which means TheFatNurse and others can only rely on the abstract to see what the study is about. This is a start, but the abstract tells us nothing about the details on how the experiment was setup, potential confounding factors and other information to allow an honest critique. By having open debate, it’ll be much more productive in moving towards the truth and confirming the validity of studies whether they are for or against the existing paradigm of fat.

References:

(1) Pharmacotherapy for mild hypertension

  1. Diana Diao1,*,
  2. James M Wright2,
  3. David K Cundiff3,
  4. Francois Gueyffier4

Editorial Group: Cochrane Hypertension Group

Published Online: 15 AUG 2012

Assessed as up-to-date: 1 OCT 2011

DOI: 10.1002/14651858.CD006742.pub2

(2) Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors

  1. F. L. Santos1,
  2. S. S. Esteves2,
  3. A. da Costa Pereira3,
  4. W. S. Yancy Jr4,5,
  5. J. P. L. Nunes3,*

Article first published online: 20 AUG 2012

DOI: 10.1111/j.1467-789X.2012.01021.x

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LowCarb/HighFat or Low Fat + medication on blood pressure

One of the things TheFatNurse has noticed about eating a reduced carb and high fat lifestyle is the drop in blood pressure TheFatNurse is experiencing. Seriously, TheFatNurse has gone from an average of 124/75ish  to…110/62…what the hell…time to look into this mofo.

This is an older study in the Arch of Intern Med from 2010 that is pretty interesting (1). It compared a low carb diet to a low fat diet + Orlistat. This drug works by preventing the absorption of fat and therefore reduce calories. Of course if you ain’t absorbing it…it’s gotta come out somewhere right? Thus, one of the potential “treatment effects” is fat oily and foul smelling stools known as steatorrhea.

Yea…TheFatNurse has random thoughts…Deal with it!

The researchers were looking to see what sort of metabolic, body weight and adverse effects these two diets would have in a 48 week period in overweight subjects with some having obesity related problems such as diabetes, lipid issues and hypertension. However, despite the low fat diet having a leg up with medication versus the low fat diet, the researchers still predicted the low carb diet would make participants lose more weight.

One of the things TheFatNurse always checks when experiments are testing low carb diets is what they mean by “low carb.”. Depending on who’s doing the study, low carb can be defined anywhere from 10 to 40 percent of one’s daily caloric intake. Even a 40% carb diet can technically be classified as low carb since the USDA Dietary Guideline For Americans actually recommends upwards of 65% of your daily diet being from carbs. The diets in this study seemed to reflect the more hardcore low carb community diet:

Participants were instructed to restrict carbohydrate intake initially to less than 20 g/d using pocket guides and hand- outs. Participants could eat unlimited meat and eggs, 112 g of hard cheese, 0.48 L of low-carbohydrate vegetables (eg, leafy greens), and 0.24 L of moderate-carbohydrate veg- etables (eg, broccoli, asparagus) daily; calorie intake was not restricted.

And the low-fat diet with orlistat:

Participants were instructed to restrict intake of total fat (<30% of daily energy), saturated fat (<10% of daily energy), cholesterol (<300 mg daily), and calories using pocket guides, hand- outs, and individualized goals.13,14 Recommended calorie in- take was 500 to 1000 kcal below a participant’s calculated weight maintenance intake.15 In addition, a 30-day supply of orlistat (120 mg before meals 3 times a day) was provided monthly.

Notice something? The low-carb diet had no restriction in calories but the low fat diet followed the usual protocol of eating below your maintenance caloric intake (along with the usual less than 10% saturated daily fat and less than 300 mg daily cholesterol. So what were the results?

Despite the different diets, both groups lost similar weight with no statistical differences. Additionally, triglycerides, LDL-C, HDL-C improved in both groups with no statistical differences either (remember tho, the LDL/HDL  cholesterol isn’t the true benchmark, its the particles but no lipoprotein particle testing was done here). Additionally, TheFatNurse thought the Hemoglobin A1c1% change was pretty interesting. A1C1 measures your sugar levels for the past 3 months and in this study the percent of change was -0.30 (CI; -0.52 to -0.09) for the low carb diet compared to the -0.06 (CI; -0.36 to +0.14) for the low fat diet with orlistat. That’s a pretty good change, although it wasn’t statistically significant (P=0.10); This means there’s a 10% probability that the differences were due to chance. Just an interesting observation.

Perhaps the most interesting portion was the Blood pressure readings. The low carb diet won out with a difference of (in mm Hg)  -7.44 (CI;-11.12 to -3.75) systolic and -4.97 (CI;-7.64 to -2.29) diastolic. with P values for both <.001. People eating the low fat diet with Orlistat actually increased their blood pressure on average.

When one thinks about the diet composition of the low carb group with the results its pretty interesting. Remember the instructions, “eat unlimited meat and eggs.” This translated to the low carb group eating not only more calories in general, but almost double the amount of total fat on a daily basis. As for saturated fat? The low carb group ate a little bit more than double the saturated fat on average daily than the low fat group. Cholesterol intake? Well over double on average compared to the low fat group.

Contrast that with what’s in TheFatNurse’s review textbook that TheFatNurse used for the nursing licensure exam on reducing hypertension:

“Consume a diet low in fat, saturated fat, and cholesterol.”

Hmm…quite the opposite results we got in this study? So why is this? Well the lower carbohydrates consumed will effect the body’s insulin levels. insulin has an effect on the kidneys. It causes your kidneys to retain salt and therefore lead to increased blood pressure. Is this new to you? TheFatNurse thinks it might be for a lot of people, but it shouldn’t be considering “the sodium-retaining effects of insulin have been known for a long time [since 1953].” (2)

Bottomline: TheFatNurse is not against low fat per se, just against the stigma that fat has gotten in today’s society. Additionally, please don’t make the mistake of treating this study as a low fat vs low carb high fat diet (LCHF) fight because the inclusion of orlistat makes true comparisons difficult. Not to mention this is just one study. TheFatNurse used this study to show results can run contrary to what is taught about eating fat and changes inside the body.

Other News: Yes TheFatNurse is updating at a snails pace so far lol. Lots of changes going on right now with TheFatNurse, will hopefully start posting more regularly once things settle down

References:

1) William S. Yancy Jr, MD, MHS; Eric C. Westman, MD, MHS; Jennifer R. McDuffie, PhD, RD, MPH; Steven C. Grambow, PhD; Amy S. Jeffreys, MStat; Jamiyla Bolton, MS; Allison Chalecki, RD; Eugene Z. Oddone, MD, MHS (2010). A Randomized Trial of a Low-Carbohydrate Diet vs Orlistat Plus a Low-Fat Diet for Weight Loss. Arch of Intern Med. 170(2) 136-145

2) B. Grunfeld, M. Gimenez, M. Balzaretti, L. Rabinovich, M. Romo,  and R. Simsolo (1995) Insulin Effect on Renal Sodium Reabsorption in Adolescent Offspring of Essential Hypertensive Parents. Hypertension 26  1089-1092.