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BTD Forums  /  Journal Club and Literature Review  /  Carnitine (red meat) and Cardiovascular Health*
Posted by: Lloyd, Monday, April 8, 2013, 12:40am
http://www.sciencedaily.com/releases/2013/04/130407133320.htm

Quoted Text
The study shows that bacteria living in the human digestive tract metabolize the compound carnitine, turning it into trimethylamine-N-oxide (TMAO), a metabolite the researchers previously linked in a 2011 study to the promotion of atherosclerosis in humans. Further, the research finds that a diet high in carnitine promotes the growth of the bacteria that metabolize carnitine, compounding the problem by producing even more of the artery-clogging TMAO.


And:(bolding mine)

Quoted Text
Additionally, they found specific gut microbe types in subjects associated with both plasma TMAO levels and dietary patterns, and that baseline TMAO levels were significantly lower among vegans and vegetarians than omnivores. Remarkably, vegans and vegetarians, even after consuming a large amount of carnitine, did not produce significant levels of the microbe product TMAO, whereas omnivores consuming the same amount of carnitine did.
"The bacteria living in our digestive tracts are dictated by our long-term dietary patterns," Hazen said. "A diet high in carnitine actually shifts our gut microbe composition to those that like carnitine, making meat eaters even more susceptible to forming TMAO and its artery-clogging effects. Meanwhile, vegans and vegetarians have a significantly reduced capacity to synthesize TMAO from carnitine, which may explain the cardiovascular health benefits of these diets."
Posted by: cindyt, Monday, April 8, 2013, 1:44am; Reply: 1
I heard this on the news.  It seems rather alarming for Hunters.
Posted by: kitari, Monday, April 8, 2013, 2:26am; Reply: 2
So what meats exactly are the red carnitine ones?  Beef? Any others?
Posted by: Lola, Monday, April 8, 2013, 3:02am; Reply: 3
very A like study, no?
Posted by: yaeli, Monday, April 8, 2013, 6:06am; Reply: 4
Quoted from Lola
very A like study, no?
Not applicable in O?  ??)

Posted by: Amazone I., Monday, April 8, 2013, 6:45am; Reply: 5
as Lola mentioned!!! It always depends of the taken parameters... that's why I always try to point out why those studies are more then ??) :o :-/ :P
O's do have the most of acids in their stomach... and now tell me.... use your mind please ;) :D... what will happen with bacteria and acidity..... = yeehhha you've got it....exactly..... they're gone ;) ;D... ok perhaps not all if pylorie has embraced you but normally... that's the fact happening

(smile)(smarty)(whistle)
Posted by: yaeli, Monday, April 8, 2013, 9:59am; Reply: 6
Right, not applicable in O thanks to the high stomach acid concentration.  8)
Posted by: Dr. D, Monday, April 8, 2013, 11:53am; Reply: 7
The more I look at this the less clearcut it becomes. Many other elements can convert to Trimethylamine N-oxide besides carnitine, including any and all phospholipids, which are a major component of the cell membrane. Much of this is under the control of the gut flora, but TMAO has some beneficial functions in protein folding and urea metabolism as well.  Indeed in some studies its beneficial effects in refolding misfolded proteins were deemed to be cardioprotective.

BTW, there is plenty of TMAO in fish. Its bioconversion is responsible for the 'fishy' odor of non-fresh fish.

I may be wrong and correct me if I am, but the burst in TMAO was observed in humans, but the atherogenicity was observed in mice? Thus the variable, which perhaps is yet to be determined, is the microbiome (floral) variations between the two species. Also, urea itself is cardioprotective, so low urea levels plus high TMAO might have a unique response profile of its own. It's one thing to observe a burst in a chemical after a meal containing a nutrient  and quite another to feed 1% of an animal's body weight of that nutrient and observe a disease resulting from it.

Finally blood groups vary significantly in the content of their cut flora.
Posted by: Lloyd, Monday, April 8, 2013, 12:06pm; Reply: 8
Quoted from Dr. D

I may be wrong and correct me if I am, but the burst in TMAO was observed in humans, but the atherogenicity was observed in mice? Thus the variable, which perhaps is yet to be determined, is the microbiome (floral) variations between the two species.


All the article mentions is this:

Quoted Text
They also examined the cardiac effects of a carnitine-enhanced diet in normal mice compared to mice with suppressed levels of gut microbes, and discovered that TMAO alters cholesterol metabolism at multiple levels, explaining how it enhances atherosclerosis.


Which seems to suggest it is the level of microbes (mouse) that made the difference. I don't know how those microbes compare to human microbes and which of those responsible for the effect are blood-type dependent.

As you say, there is a lot the study doesn't say and there is not enough information here to draw any clear conclusions. One of the conclusions that cannot be drawn is that the study can be dismissed as being 'A' like or some such other thing. We just don't know. This stuff is complicated.

My own observation is that the O or Hunter diet still has less carnitine than what is present in most meat-eating diets because the portions are smaller than most would eat and the frequency is a bit less.

"When in trouble, when in doubt, run in circles - scream and shout." - Anon
Posted by: yaeli, Monday, April 8, 2013, 2:19pm; Reply: 9
Quoted from Lloyd
"When in trouble, when in doubt, run in circles - scream and shout." - Anon
Don't hesitate to call thy helper, even if you think he may be asleep.

Posted by: Dr. D, Monday, April 8, 2013, 2:36pm; Reply: 10
This is the same authors prior article on choline promoting atherogenesis through conversion by gut bacteria into TMAO:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3086762/
Posted by: Lloyd, Monday, April 8, 2013, 3:11pm; Reply: 11
Quoted from Dr. D
This is the same authors prior article on choline promoting atherogenesis through conversion by gut bacteria into TMAO:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3086762/


Quoted Text
Hepatic FMO3 is a known enzymatic source for TMAO in humans, based on the recent recognition of the etiology of an uncommon genetic disorder called trimethylaminuria (also known as fish malodor syndrome)15,17. Subjects with this metabolic condition have impaired capacity to convert TMA, which smells like rotting fish, into TMAO, an odorless stable oxidation product17


Fish again!  :D


Quoted Text
Using a targeted metabolomics approach aimed at identifying plasma metabolites whose levels predict risk of CVD in subjects, we have identified a novel pathway linking dietary lipid intake, intestinal microflora and atherosclerosis (Fig. 6). The pathway identified (dietary PC/choline -> gut flora-formed TMA -> hepatic FMO-formed TMAO) represents a unique additional nutritional contribution to the pathogenesis of CVD that involves choline metabolism, an obligate role for the intestinal microbial community, and regulation of surface expression levels of macrophage scavenger receptors known to participate in the atherosclerotic process.


Seems like they are trying to build on this previous paper.

Quoted Text
the participation of FMOs in human atherosclerosis and HDL cholesterol levels remains to be established. Strong associations between systemic TMAO levels and both angiographic measures of coronary artery atherosclerotic burden and cardiac risks were observed among subjects; however, no correlation was observed between plasma TMAO levels and HDL cholesterol levels in subjects.


Acknowledges that there are other factors.

Overall, just one more puzzle piece. What and how much of this information is of dietary use is not clear to me.
Posted by: Dr. D, Monday, April 8, 2013, 4:56pm; Reply: 12



Awful lot of mice with zero TMAO and lesions and the mice with the highest levels of TMAO were under the confidence interval for association with lesions..
Posted by: Lloyd, Monday, April 8, 2013, 5:17pm; Reply: 13
The TMAO lesion scatterplot is all over the place. If you throw out the limited number around 0,0 the effect is negligible.
Posted by: kitari, Monday, April 8, 2013, 5:32pm; Reply: 14
Would secretor status also be an issue to consider in O's since "the overall composition of bacteria in your intestinal ecosysteme" is influenced by secretor status?
Posted by: Lloyd, Monday, April 8, 2013, 6:16pm; Reply: 15
Quoted from kitari
Would secretor status also be an issue to consider in O's since "the overall composition of bacteria in your intestinal ecosysteme" is influenced by secretor status?


I think the answer I would give is probably something along the lines of:

"The information from these studies show additional metabolomics CVD interrelations previously unreported. While there is enough data to warrant further investigation for specific targets or target populations there is limited value of this information for general dietary use".

Yes, secretor status does influence the overall composition of bacteria in your intestinal ecosystem. So do antibiotics, infections/illness, diet/supplements and other natural causes.

Posted by: Patty H, Tuesday, April 9, 2013, 10:46pm; Reply: 16
Maybe the MICE should stay away from red meat  ;D  Sorry - couldn't resist that one!
Posted by: cindyt, Wednesday, April 10, 2013, 12:35am; Reply: 17
Diane Rehm had a program on this today.  You can listen to it here http://thedianerehmshow.org/shows/2013-04-09/new-research-red-meat-and-heart-disease

Her guests were:  
Dr. Michael Lauer  director of the division of cardiovascular sciences, National Heart, Lung, and Blood Institute (NHLBI) at the National Institutes of Health (NIH).
Dr. Stanley Hazen  chair of the department of cellular and molecular medicine, Cleveland Clinic's Lerner Research Institute.
Duffy MacKay  vice president of scientific and regulatory affairs for the Council for Responsible Nutrition.
Shalene McNeill  executive director of human nutrition research at National Cattlemen's Beef Association (NCBA).

Needless to say, they didn't all agree.  Hazen was one of the researchers, but he spent little time on the program.
Posted by: Tom Martens, Wednesday, April 10, 2013, 12:30pm; Reply: 18
They didn't mention that half or more of those vegans and vegetarians were blood type O's  :)
Posted by: D.L., Wednesday, April 10, 2013, 9:34pm; Reply: 19
It was recommended that I take an l-carnitine supplement for my heart. Some MDs and NDs recommend it. What about that? I've been taking it for more than 3 years.
Posted by: yaeli, Wednesday, April 10, 2013, 10:47pm; Reply: 20
I take 1 x daily Source Naturals' Acetyl L-carnitine & Alpha-Lipoic Acid.
Posted by: Amazone I., Thursday, April 11, 2013, 7:15am; Reply: 21
the acetyl-l'carnitine is merely a beautiful sustain for brains....;) .... ;D entre-autre ....(cool)(smarty) but in adjuvance with r-alpha-lipoic acid a beautiful helper as an antioxidant  and detoxer as well  :D
Posted by: yaeli, Saturday, April 13, 2013, 5:21am; Reply: 22
Quoted from Amazone I.
the acetyl-l'carnitine is merely a beautiful sustain for brains....;) .... ;D entre-autre ....(cool)(smarty) but in adjuvance with r-alpha-lipoic acid a beautiful helper as an antioxidant  and detoxer as well  :D
(pray) (think) (smartyp)
Posted by: Rex, Monday, May 6, 2013, 8:36pm; Reply: 23
I can only speak for myself here.  I've been following the Type O diet since 2007.  I too was afraid of eating meat of any kind but I decided to give it a try and see what happens.  What happened was that I have never felt better in my life.  I do not take any perscription medications, as do many of the folks that I know who are my age (74) and much younger.  My energy level is right up there with folks half my age.  I do not suffer from arthritis nor do I get sick very often.  In short, I have just followed Dr.D's recommendations for my blood type and I have never been sorry that I did.  
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