gastric inflammation and cardiovascular disease

7/28/2019 Gastric Inflammation and Cardiovascular Disease

1/8

www.medscape.com

Beef, Microbes in the Gut, and Heart Disease

An Expert Interview With Stanley L. Hazen , MD, PhDLinda Brookes, MSc, Stanley L. Hazen, MD, PhD

Jun 19, 2013

An Expert Interview With Stanley L. Hazen, MD, PhDAbout the Interviewee

Stanley L. Hazen, MD, PhD, isDepartment Chair of Cellular and Molecular Medicine, Section Head ofPreventive Cardiology and Rehabilitation, and Vice Chair of Translational Research at the Lerner ResearchInstitute, Cleveland Clinic, Cleveland, Ohio.

Dr. Hazen describes the long-term goal of his laboratory as the understanding of the mechanisms throughwhich inflammation contributes to diseases such as atherosclerosis and asthma. Current research programsare focused on the role of myeloperoxidase in promoting oxidant stress in vivo, and its participation incardiovascular diseases; HDL structure and function; the roles of peroxidases and tobacco exposure in airwayremodeling in asthma; and the role of intestinal microbiota in cardiometabolic disease. All research projects relyheavily on chemical and analytical methods to identify specific reactions/products, their mechanisms of

formation, and their use as probes to elaborate pathways responsible for disease. Research efforts in eachprogram span from bench to bedside, including basic/genetic, cellular, animal model, and human clinicalinvestigations.

The Studies

Dr. Hazen was lead investigator and senior author of:

Koeth RA, Wang Z, Levison BS, et al. Intestinal microbiota metabolism of l-carnitine, a nutrient in red meat,promotes atherosclerosis. Nat Med. 2013;19:576-585.

Tang WHW, Wang Z, Levison BS, et al. Intestinal microbial metabolism of phosphatidylcholine andcardiovascular risk. N Engl J Med. 2013;368:1575-1584.

Background to the InterviewTwo recently published studies, [1,2] led by Dr. Hazen and colleagues at Cleveland Clinic and supported by boththe National Institutes of Health and the Office of Dietary Supplements, have provided evidence suggesting thatconsuming common foods such as meat, eggs, and dairy products may directly contribute to an increased riskfor cardiovascular disease in a way that is not related to the cholesterol or saturated fat content of the food. Theresearchers showed for the first time that carnitine found in red meat, and choline derived from consumingthese foods, is metabolized by gut microbes to trimethylamine (TMA), which in turn is absorbed into thebloodstream and metabolized in the liver to trimethylamine-N-oxide (TMAO), a substance believed to promoteatherogenesis. Both studies found an association between high levels of TMAO and increased cardiovascularrisk in humans. These studies build on other recently published data from Dr. Hazen and colleagues reportingon the pathway in both humans and mice linking microbiota metabolism of dietary choline andphosphatidylcholine to cardiovascular disease pathogenesis, and demonstrating a direct proatheroscleroticeffect of TMAO.[3,4]

The first of the more recent studies investigated the effects of dietary L-carnitine, a choline analogue containinga similar TMA structure and found in red meat.[1] Human subjects who consumed L-carnitine as an 8-oz sirloinsteak plus 250 mg isotope-labeled L-carnitine showed increased formation of both endogenous and isotope-labeled TMAO. This increase in TMAO was almost completely suppressed when a week-long treatment withantibiotics was given beforehand, indicating that TMAO is produced from dietary L-carnitine via a microbiota-dependent mechanism. Omnivores produced more TMAO than vegans or vegetarians following ingestion of L-carnitine. The presence of specific bacterial taxa in human feces was associated with both plasma TMAOconcentration and dietary status. In an independent cohort of 2595 persons undergoing cardiac evaluation,plasma L-carnitine levels predicted increased risks for both prevalent cardiovascular disease and incidentmajor adverse cardiac events (myocardial infarction, stroke or death), but only among persons with concurrent
http://www.medscape.com/http://www.medscape.com/http://www.medscape.com/


2/8

high TMAO concentrations, suggesting that TMAO is the primary driver of association of L-carnitine withcardiovascular risk.

The researchers also investigated chronic dietary L-carnitine supplementation in mice, which altered cecalmicrobial composition, markedly enhanced synthesis of TMA and TMAO, and increased atherosclerosis, butnot when the intestinal microbiota was concurrently suppressed. In mice with an intact intestinal microbiota,dietary supplementation with TMAO, or either L-carnitine or choline, reduced in vivo reverse cholesterol

transport, suggesting that generation of TMAO by gut microbiota impairs reverse cholesterol transport. Finally,the investigators described additional studies that revealed that TMAO supplementation altered cholesterol andsterol metabolism in multiple compartments (artery wall, liver, intestines), so the mechanisms through whichTMAO enhances atherosclerosis appear to be mediated via changes in cholesterol and bile acid metabolism.

Dr. Hazen and coauthors commented on the health-related implications of these findings, notably that thesestudies may help explain the well-known epidemiologic association between dietary red meat ingestion andatherosclerosis and the need to investigate the safety of chronic consumption of over-the-counter L-carnitinedietary supplements.

The second study investigated the relationship between intestinal microbiota-dependent metabolism of dietaryphosphatidylcholine, the major dietary source of choline, with TMAO levels and adverse cardiovascular eventsin humans.[2] After a phosphatidylcholine challenge involving ingestion of 2 hard-boiled eggs and deuterium[d9]-labeled phosphatidylcholine in 40 healthy persons, time-dependent increases were seen in both TMAO

and d9-TMAO. Levels of TMAO and d9-TMAO were undetectable after another challenge followingsuppression of intestinal microbiota with oral broad-spectrum antibiotics for 1 week, then reappeared afterwithdrawal of the antibiotics. These studies were thus consistent with gut microbes playing a role in TMAOformation from ingestion of phosphatidylcholine, which is abundant in egg yolk.

The authors also described a separate clinical study[2] in which 4007 sequential consenting patients (mean age,63 years; two thirds men) undergoing elective coronary angiography were examined. Increased plasma levelsof TMAO were associated with a significantly increased risk for a major adverse cardiovascular event (hazardratio, 2.54 for highest vs lowest TMAO quartile; P< .001) over 3 years of follow-up. This increased riskpersisted after adjustment for traditional risk factors. These results supported the previous findings suggestingthat pathways dependent on the gut microbiota might contribute to the pathophysiology of cardiovasculardisease, concluded Dr. Hazen and his colleagues. Among other implications, these findings suggest thatexcessive consumption of phosphatidylcholine/choline-containing foods should be avoided.

In an editorial in the New England Journal of Medicine,[5] Joseph Loscalzo, MD, PhD (Brigham and Women's

Hospital and Harvard Medical School, Boston, Massachusetts), said that the studies "point to a truly novel andpotentially modifiable risk factor for atherothrombotic vascular disease." However, "much remains to be done todetermine the precise role of TMAO in atherothrombogenesis -- whether it has a direct effect, acts as anepiphenomenal biomarker, or is a precursor to a more direct effector."

Dr. Hazen spoke to Medscape about the implications of both studies.

The Role of Microbes in the Gut and Compounds in Red Meat

Medscape: Both of your recent studies have been viewed as having implications for nutrition,especially as related to newly identified adverse effects associated with the consumption of L-carnitine(in meat) and dietary phosphatidylcholine (in meat, eggs, dairy products).

Dr. Hazen: That was just the media hype; we never really pushed that point at all. We have been focusing on

the biochemical determinants of atherosclerosis and following where the chemistry and biology lead us, and ithappened that some compounds involved are part of the foods we eat on a regular basis. I have been trying toavoid making too many statements about nutritional recommendations, other than saying that I think we shouldbe following what is recommended by the American Heart Association.[6] We also referred to a recent study inwhich people who consumed a Mediterranean diet, specifically avoiding red meat, showed a 30% reduction incardiovascular events over almost 5 years.[7]

Medscape: Nonetheless, the compounds that were the focus of your studies are usually referred to as"essential" nutrients, or as you referred to choline, "semi-essential," and people take them assupplements even if they don't have a deficiency.


3/8

Dr. Hazen: Words like "essential" are used very loosely. Carnitine is not essential. We make all the carnitinewe need from other nutrients found in foods, vegan and omnivore alike. Choline is considered "semi-essential"from a nutritional standpoint because our bodies can make most of the choline needed, but we do need toconsume some in our diets or we develop a deficiency state -- which is very rare on a Western diet. Of course,choline is a major component of phosphatidylcholine, the building blocks of our cell membranes, so we couldnot live without it. However, this does not mean that we have to consume it in a capsule, enema, or in any otherform as a supplement.

Medscape: Both of your studies were focused on the catabolism of choline to TMA by gut microbesand then hepatic conversion of TMA to TMAO. You have published other detailed studies on thispathway[3,4]; could you explain what changes your research has brought about in the way of thinkingabout it?

Dr. Hazen: First, choline, carnitine, and phosphatidylcholine, which are all dietary nutrients, all contain a similarTMA structure. TMA is generated through cleavage of that structure by gut bacteria. TMA is actually a gas,both at body and room temperature. It smells like rotting fish, and people who have a defect in the hepaticenzymes that convert TMA to TMAO have a genetic disorder, trimethylaminuria, also called fish malodorsyndrome. Up until the time of our studies, TMAO in humans was thought to be simply a nitrogenous wasteproduct excreted in the urine. It is a very stable, small molecule and dialysis specialists have long used TMAOmeasurement as a way of assessing the efficacy of dialysis membranes. That is also one of the reasons whywe think that this pathway is going to be particularly important, not just in everyone, but especially in people

with chronic kidney disease and end-stage renal disease. As the excretion of TMAO becomes worse, it starts toaccumulate, and we think that this may account in part for enhanced cardiovascular risk in people with chronickidney disease and end-stage renal disease. It is known that traditional risk factors do not adequately capturethat enhanced risk in renal patients, but is not exactly known what the pathways involved in cardiac risks inthese patients are. So, it is a logical leap that TMAO is involved.

Medscape: Could you explain more about what you believe to be the link between TMAO and increasedcardiovascular risk in patients?

Dr. Hazen: It is important to stress that this increased risk associated with TMAO level is not an alternative tocholesterol; it is in addition to cholesterol. It appears that TMAO is mechanistically supporting enhancedatherosclerosis by changing cholesterol and sterol metabolism in multiple different compartments in the body.

In the artery wall, TMAO influences the macrophage foam cell, which is the major cellular hallmark of anatherosclerotic plaque. In the presence of TMAO there are changes in expression levels of multiple different

genes, including ones that have been linked to enhanced cholesterol deposition, such as scavenger receptors.

In the liver we showed that bile acid synthesis is inhibited because the major enzymes involved, Cyp7a1 andCyp27a1, are both suppressed. In addition to reduction in bile acid pool size, the composition of the bile acidsalso changes, and multiple transporters involved in moving bile acids across the different membranes in thehepatocyte are reduced. The same process takes place in the enterocyte in the intestines; we see changes incholesterol and sterol metabolism.

So, cholesterol is necessary to promote atherosclerosis; it is the major lipid that deposits in the artery wall. Iwould compare it to the electricity needed to turn on a light bulb: TMAO functions like a dimmer switch; if youturn a dimmer switch on all the way up (TMAO increased) with a certain amount of electricity (cholesterol), youwill get a lot of light (plaque). If you turn the dimmer switch down (TMAO decreases), for the same amount ofelectricity (cholesterol) there will be less light (atherosclerotic plaque). So, the net effect of the TMAO isenhancing the potential for cholesterol to get deposited in cells of the artery wall and reducing the elimination of

sterols from the body by the pathway called reverse cholesterol transport.

Medscape: So, you are saying that TMAO is a causal factor, not just a marker like high-sensitivity C-reactive protein?

Dr. Hazen: Yes. The reason why I think it is causal is because if you feed it to animals, they get acceleratedatherosclerosis. The point that may be a little confusing is, how can it be linked to cholesterol metabolism andnot change LDL- or HDL cholesterol levels? HDL- and LDL cholesterol are just surrogates for pathways -- thatis, for moving cholesterol; they are not measures of function. Each is a snapshot of how much cholesterol there


4/8

is at a certain point. HDL tends to move cholesterol from the periphery centrally, into the liver, and out of thebody, and LDL delivers cholesterol to the peripheral tissues. They do not tell you anything about flux.

Experts in the HDL community have been saying for a long time that HDL cholesterol is a surrogate and not asgood as HDL function.Technically speaking, that is true also for LDL. In fact, none of the things that we havemechanistically seen TMAO doing should influence LDL cholesterol, and we do not see any relationshipbetween TMAO and LDL or HDL.

Medscape: These experiments were in mice; how relevant are the results to humans?

Dr. Hazen: There are certainly many differences between animals and humans. We proved mechanistically inmice that TMAO directly enhances atherosclerosis in atherosclerosis-prone mouse models. We also showedthat you can reduce reverse cholesterol transport with either TMAO or the foods containing the precursors,choline or L-carnitine, which both reduce reverse cholesterol transport, but only in the presence of intact gutflora. As soon as you suppress the gut flora, you no longer reduce it. However, in humans we do not yet havedata connecting TMAO to reverse cholesterol transport, because no one yet knows how to measure it inhumans. What we do see in humans is a very strong correlation between circulating levels of TMAO and bothprevalent cardiovascular disease and future risk for heart attack, stroke, death, need for heart surgery -- all theadverse cardiovascular events.

Medscape: So, you showed that this association has no direct relation to cholesterol levels?

Dr. Hazen: We showed that TMAO predicts cardiovascular outcomes regardless of cholesterol levels. Whenwe analyzed the data above and below an LDL cholesterol level of 100 mg/dL or 70 mg/dL, as well as aboveand below HDL 45 mg/dL, apoB above and below 80 mg/dL, or apoA1 above and below 100 mg/dL, therelationship between TMAO and cardiovascular risk did not change.[2] It is remarkable how robust theprognostic value of this TMAO is, regardless of all the different risk factor tests.

Medscape: Was it also predictive in different subgroups?

Dr. Hazen: The association was apparent in persons with or without cardiovascular disease, as well as withindiabetic and nondiabetic persons alike, or those with vs without hypertension and smokers or nonsmokers --whichever way we looked at it.[2]

The Role of TMAO in Cardiovascular Residual Risk

Medscape: Could this represent the residual risk for cardiovascular disease identified in patients withlow LDL cholesterol levels on statin therapy?[8] Recent studies that focused on reducing this risk byincreasing low levels of HDL cholesterol do not appear to have been successful.[9,10] Could loweringTMAO be the way to reduce that residual risk?

Dr. Hazen: Perhaps.In the New England Journal of Medicine paper[2] we reported that, statistically, inclusion ofTMAO as a covariate resulted in a net 8.6% reclassification for improvement in risk estimation over traditionalrisk factors (net reclassification improvement, a significant P< .001). I hesitate to call it "residual risk"; it isindependent of LDL- and HDL cholesterol levels. Once we can find people at risk, the next step is whether wecan inhibit or treat that risk. Obviously these studies need to be done in the future, both attacking this pathwayand seeing whether it represents a new therapeutic angle for lowering cardiovascular risk. It does not evenhave to be drugs, because it seems that nutrition and diet approaches can make a difference. However, we willalso need to determine whether, by identifying someone who is at risk, in the same way as with high-sensitivityC-reactive protein, we can identify a population that has a higher risk and then get them to more aggressive

goals -- for example, by intensifying statin therapy. Would these people benefit from more aggressivepreventive efforts?

Medscape: Would you risk creating a "worried well" population of patients with no symptoms butraised TMAO?

Dr. Hazen: In our cohort of over 1000 primary prevention patients, we found that TMAO predicted future riskquite well. It is almost a CAD risk equivalent, a twofold increase, which is equivalent to the risk of havingdiabetes in our cohort. And those were people who just had a coronary angiogram and were told that there isless than 50% stenosis in all of their major vessels and they did not have anything to worry about. So, more


5/8

studies need to be done to see who should have their TMAO measured. The present study was not a smallnumber of people, and the data are pretty strong.

Medscape: How can TMAO be measured nowadays?

Dr. Hazen: TMAO is straightforward to measure. We currently use mass spectrometry, but this is time-consuming and not something that one can order from the hospital lab. We are currently involved in the

development of a test using nuclear magnetic resonance (NMR). It turned out that the hydrogens on TMAO areunique and have a different NMR signature. The Cleveland Clinic has licensed the technology for measuringTMAO to LipoScience (Raleigh, North Carolina).[11,12] LipoScience uses NMR-based technology to measurelipoprotein particle subfractions and does about 2 million lipoprotein assays per year. The same technique thatmeasures LDL and HDL particles can be applied to measure TMAO. The plan is for our clinical assay to beavailable for measuring TMAO through this platform by the end of summer 2013. Their machine has recentlybeen cleared by the US Food and Drug Administration for availability in hospital labs.[13] It will not be availableso quickly for TMAO measurement, but at least TMAO testing will be available for research studies before theend of the year.

In the future, just like we do a blood test for cholesterol and triglycerides, we may do a blood test for TMAO foradvice on dietary patterns as well as for other bacterial products that we think are biologically linked to glucosemetabolism. These are going to be the subjects of future papers.

We should be thinking of our intestinal microbial community as the largest endocrine organ in our body. Thenutrients you ingest go through the filter of the intestinal microbes, and depending on the nutrient input andmicrobial composition, you have a different capacity to make different biologically active compounds.Compounds that diffuse in the blood and act at a different site meet all the definitions of a hormone, so this iswhy the microbial community can be considered like an endocrine organ, in a way.

Medscape: How would one lower high levels of TMAO? Would it be by diet, or would it mean treatingindividualized gut microbiota?

Dr. Hazen: Dietary efforts, including reduction in meat consumption, appear to be associated with reducedTMAO levels. As for treating an "individual gut microbe"? There are trillions of microbes, but if you look at thetop 95% of them, in terms of broad classifications of family and genus they are pretty much the same ineveryone. Proportions may be shifted in someone who eats a more vegetarian diet with more roughagecompared with someone who has more carnivorous eating patterns, but the 95% are similar except for someproportional changes. In that 5% is where there is huge variability. If you are talking about a microbe making a

product that is biologically active, it need not be abundant; it can be a really small proportion, because it ismaking something catalytically. It does not have to be one of the major microbe types; it just has to be presentin sufficient numbers to produce the compound at a blood level that will allow us to see if it causes whateverphenotype we are looking at.

One of the really intriguing findings of our L-carnitine paper was how substantially different the metabolism wasof carnitine in vegetarians and vegans compared with omnivores. Chronic exposure to a diet that included L-carnitine shifted the microbiota composition. It was a subtle shift, but the proportions of the microbes thattracked with TMAO levels in vegan or vegetarian status still accounted for a very small proportion of themicrobes in the entire intestines. The vast majority of the microbes are similar among omnivores, vegetarians,and vegans.

Medscape: Does that mean that if you eat any meat at all on a regular basis, whether a small amount orlarge portions, your gut microbiota are similar?

Dr. Hazen: We do not know. To be defined as a vegetarian or a vegan in our studies, participants had to claimto have no meat product during the past year. How long you have to change your diet before you see a shift,we do not know. But at least now we can measure blood levels of TMAO, and it is going to be much easier thantrying to look at the entire microbiome in the stool.

Medscape: In your studies you used antibiotics to suppress the gut microbiota, but presumablytreatment with antibiotics to suppress production of TMAO would not be a good idea.

Dr. Hazen: Right. In fact, not only would it not be a good idea, it would be futile. What we already saw, at leastin mice, is that when we initially did our experiments with only one antibiotic, we completely eliminated TMAO


6/8

levels at the beginning, but when we harvested the aortas just over half a year later, we found that blood TMAOlevels were completely back to normal because the intestinal microbes had developed tolerance. So, even if,let us say, a fraction of 1% has a resistance to the antibiotic, in the beginning it looks as though the TMAO is99% inhibited. But at 20 weeks it is back up to normal, because bacteria have numbers on their side. Theyhave a doubling time in hours, and the very low-abundance resistant forms have a selective advantagebecause all the susceptible bacteria are being eliminated. None of the clinical trials of chronic antibiotic use inatherosclerosis have been successful to date. [14-16] My suspicion is that if the antibiotic had inhibited TMAO

production in the beginning, I see no reason why it would do so after a continuous year of use of the antibiotic,as any resistant microbial form would eventually take over and repopulate the intestines.

Medscape: So, that is not something that physicians will be considering in the future, but do you thinkthey can be doing anything else at this stage?

Dr. Hazen: Two things. One is that the test for TMAO will be available on a limited basis -- not widely availablein every lab -- before the end of the year. Second, these studies basically reinforce a lot of existing knowledgein terms of diet. These kinds of studies do not address how much you eat and how much is linked to heart risk.That is done by epidemiology studies like the Health Professionals Follow-Up Study or the Nurses' HealthStudy, in which over 100,000 people have been followed for over 20 years with over 1 million patient-years offollow-up and thousands of mortality events. It is that kind of data, which involves very detailed foodquestionnaires given out every few years over the course of several decades, that allow us to conclude thateating 1 portion of red meat per day accounts for about a 13% increase in risk for total, cardiovascular, and

cancer mortality over an average follow-up period of 22 years.[17]

From our studies we perhaps now understand at a mechanistic level why red meat is more associated withcardiovascular risk than would be predicted simply by its cholesterol or saturated fat content. If you look at themortality data from large studies, and then at the cholesterol content of red meat and the saturated fat content,neither is high enough to account for the enhanced mortality risk, [18] and that is why people have argued thatthere may be another contributor, such as grilling meat, which produces high benzo[a]pyrene concentrations, orthat people who eat steak also increase their sodium intake.

Medscape: There is also a carcinogenic effect.

Dr. Hazen: There is, and whether or not this pathway is linked is something that needs to be determined.

Medscape: Can you say how much people should cut back on foods containing L-carnitine orphosphatidylcholine?

Dr. Hazen: They should try cutting back on foods that are particularly rich in them, which goes almost hand inhand with cutting back on foods rich in cholesterol and saturated fat. That is because animal cells do not justhave free-floating fat and cholesterol; they are bound in membranes inside the cells. The major building blockof membranes is lecithin or phosphatidylcholine, so almost every type of food that is high in fat and cholesterolis also high in phosphatidylcholine, the main dietary source of choline. Free choline also exists, but usually it isin the form of phosphatidylcholine, unless you are following a vegetarian or vegan diet, and then you areprobably getting more free choline. However, I want to be clear that I am hesitant to say that we are studyingnutrition. We are just studying the fundamental biochemical pathways linked to nutrition, and it just happensthat we have discovered a link between some of these compounds via the gut flora that make the metabolite.Essentially we first found the link between TMAO and atherosclerosis in subjects. We then reverse-engineeredthe process and determined that it comes from what we eat. It just so happens that those foods are high insaturated fat and cholesterol. So, our approach is not to say or not to make recommendations on different foodchoices; instead it is to determine what the pathway is. Personally, I like a good steak, and in the future I want

to be able to have a tablet so that I can continue to eat a small portion occasionally. I do not think that a whollyvegan diet is the way to go, because that has other associated risks, such as being high in carbohydrate andlow in vitamins B12 and D...

Medscape: Where do you see this research heading now?

Dr. Hazen: Our data are opening up 2 exciting clinical possibilities. One is the need to identify new pathwaysfor cardiovascular risk, because even lowering the LDL cholesterol below 70 mg/dL is not sufficient. There isstill significant residual risk that is not being treated with our current lifestyle changes and our currenttherapeutic approaches.


7/8

The other clinical possibility follows from the major genetic studies that have looked at attributablecardiovascular risk but have not even been able to attribute 10% of the risk. So, if it is not genes, it isenvironment, and our biggest environmental exposure is what we eat, which is a foreign body being ingested.Two different people can experience the same food differently because they have different gut flora. Oneperson may generate a little more of a compound like TMAO than the other. That concept is a new way ofthinking about complex diseases like atherosclerosis and other cardiometabolic diseases. It can also apply toobesity and insulin resistance. Data links intestinal flora involvement in those phenotypes in both mice and

humans.[19-21]

There have been very exciting data from a gut flora transplant in persons with metabolic syndrome whoreceived either their own fecal samples or those from a lean donor. Persistent changes in insulin sensitivityoccurred just by transplanting the intestinal flora from one individual to another. [22] That is a whole new way ofthinking, and it might lead to opportunities for new therapeutics.

I now think of statins, HMG-CoA reductase inhibitors, lowering LDL cholesterol, as ourHomo sapiens enzymeinhibitors. I predict in our future that we will also have in our medicine cabinets drugs that target bacterialenzymes -- not antibiotics, but compounds that just inhibit the microbe enzyme activity so that they continue tolive but without being able to generate the metabolite that we are trying to suppress. I think that is going to be anew and exciting kind of therapeutic for heart disease in the future.

References

1. Koeth RA, Wang Z, Levison BS, et al. Intestinal microbiota metabolism of l-carnitine, a nutrient in redmeat, promotes atherosclerosis. Nat Med. 2013;19:576-585.Abstract

2. Tang WHW, Wang Z, Levison BS, et al. Intestinal microbial metabolism of phosphatidylcholine andcardiovascular risk. N Engl J Med. 2013;368:1575-1584.Abstract

3. Wang Z, Klipfell E, Bennett BJ, et al. Gut flora metabolism of phosphatidylcholine promotescardiovascular disease. Nature. 2011;472:57-63.Abstract

4. Bennett BJ, de Aguiar Vallim TQ, Wang Z, et al. Trimethylamine-N-oxide, a metabolite associated withatherosclerosis, exhibits complex genetic and dietary regulation. Cell Metab. 2013;17:49-60.Abstract

5. Loscalzo J. Gut microbiota, the genome, and diet in atherogenesis. N Engl J Med. 2013;368:1647-1649.Abstract

6. Lichtenstein AH, Appel LJ, Brands M, et al. Diet and lifestyle recommendations revision 2006: Ascientific statement from the American Heart Association Nutrition Committee. Circulation.2006;114:82-96.Abstract

7. Estruch R, Ros E, Salas-Salvad J, Covas MI, et al; PREDIMED Study Investigators. Primaryprevention of cardiovascular disease with a Mediterranean diet. N Engl J Med. 2013;368:1279-1290.Abstract

8. Libby, P. The forgotten majority. Unfinished business in cardiovascular risk reduction. J Am CollCardiol. 2005;46:1225-1228.Abstract

9. Boden WE, Probstfield JL, Anderson T, et al; AIM-HIGH Investigators. Niacin in patients with low HDLcholesterol levels receiving intensive statin therapy. N Engl J Med. 2011;365:2255-2267.Abstract

10. Armitage J; HPS2-THRIVE Collaborative Group. HPS2-THRIVE: Randomized placebo-controlled trialof ER niacin and laropiprant in 25,673 patients with pre-existing cardiovascular disease. Program andabstracts of the 62nd Annual Scientific Session of the American College of Cardiology (ACC13 );March 9-11, 2013 ; San Francisco, California.

11. LipoScience, Inc. LipoScience announces exclusive license from Cleveland Clinic to developcardiovascular test based on gut flora metabolite. [Press release ] Raleigh, NC; April 19, 2012.http://files.shareholder.com/downloads/AMDA-ZIFX5/2473250412x0x579931/cce7f086-e5d6-49f6-bd62-

71512fd30e52/579931.pdfAccessed June 18, 2013.
http://www.medscape.com/medline/abstract/23563705http://www.medscape.com/medline/abstract/23563705http://www.medscape.com/medline/abstract/23563705http://www.medscape.com/medline/abstract/23614584http://www.medscape.com/medline/abstract/23614584http://www.medscape.com/medline/abstract/23614584http://www.medscape.com/medline/abstract/21475195http://www.medscape.com/medline/abstract/21475195http://www.medscape.com/medline/abstract/21475195http://www.medscape.com/medline/abstract/23312283http://www.medscape.com/medline/abstract/23312283http://www.medscape.com/medline/abstract/23312283http://www.medscape.com/medline/abstract/23614591http://www.medscape.com/medline/abstract/23614591http://www.medscape.com/medline/abstract/23614591http://www.medscape.com/medline/abstract/16785338http://www.medscape.com/medline/abstract/16785338http://www.medscape.com/medline/abstract/16785338http://www.medscape.com/medline/abstract/23432189http://www.medscape.com/medline/abstract/23432189http://www.medscape.com/medline/abstract/16198835http://www.medscape.com/medline/abstract/16198835http://www.medscape.com/medline/abstract/16198835http://www.medscape.com/medline/abstract/22085343http://www.medscape.com/medline/abstract/22085343http://www.medscape.com/medline/abstract/22085343http://files.shareholder.com/downloads/AMDA-ZIFX5/2473250412x0x579931/cce7f086-e5d6-49f6-bd62-71512fd30e52/579931.pdfhttp://files.shareholder.com/downloads/AMDA-ZIFX5/2473250412x0x579931/cce7f086-e5d6-49f6-bd62-71512fd30e52/579931.pdfhttp://files.shareholder.com/downloads/AMDA-ZIFX5/2473250412x0x579931/cce7f086-e5d6-49f6-bd62-71512fd30e52/579931.pdfhttp://files.shareholder.com/downloads/AMDA-ZIFX5/2473250412x0x579931/cce7f086-e5d6-49f6-bd62-71512fd30e52/579931.pdfhttp://files.shareholder.com/downloads/AMDA-ZIFX5/2473250412x0x579931/cce7f086-e5d6-49f6-bd62-71512fd30e52/579931.pdfhttp://www.medscape.com/medline/abstract/22085343http://www.medscape.com/medline/abstract/16198835http://www.medscape.com/medline/abstract/23432189http://www.medscape.com/medline/abstract/16785338http://www.medscape.com/medline/abstract/23614591http://www.medscape.com/medline/abstract/23312283http://www.medscape.com/medline/abstract/21475195http://www.medscape.com/medline/abstract/23614584http://www.medscape.com/medline/abstract/23563705


8/8

12. LipoScience, Inc. LipoScience begins clinical development of NMR-based cardiovascular diagnostictest for novel gut flora metabolite. [Press release ] Raleigh, NC; April 25, 2013.http://investor.liposcience.com/common/download/download.cfm?CompanyID=AMDA-

ZIFX5&FileID=657183&FileKey=e4ea1b3d-b0ee-4260-9ebe-

2a904ef82d9e&FileName=LPDX_News_2013_4_25_General_Releases.pdfAccessed June 18, 2013.

13. LipoScience, Inc. LipoScience receives FDA clearance for Vantera clinical analyzer. Press release.

Raleigh, NC. September 5, 2012.http://www.businesswire.com/news/home/20120905005255/en/LipoScience-Receives-FDA-Clearance-Vantera-

Clinical-AnalyzerAccessed June 19, 2013.

14. O'Connor CM, Dunne MW, Pfeffer MA, et al. Azithromycin for the secondary prevention of coronaryheart disease events: the WIZARD study: a randomized controlled trial. JAMA. 2003,290:1459-1466.

15. Grayston JT, Kronmal RA, Jackson LA, et al. Azithromycin for the secondary prevention of coronaryevents. N Engl J Med. 2005,352:1637-1645.

16. Cannon CP, Braunwald E, McCabe CH, et al. Antibiotic treatment of Chlamydia pneumoniae afteracute coronary syndrome. N Engl J Med. 2005,352:1646-1654.

17. Pan A, Sun Q, Bernstein AM, et al. Red meat consumption and mortality: results from 2 prospectivecohort studies. Arch Intern Med. 2012;172:555-563.Abstract

18. Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating theassociation of saturated fat with cardiovascular disease. Am J Clin Nutr. 2010;91:535-546.Abstract

19. Turnbaugh PJ, Ley RE, Mahowald MA, et al. An obesity-associated gut microbiome with increasedcapacity for energy harvest. Nature. 2006;444:1027-1031.Abstract

20. Turnbaugh PJ, Hamady M, Yatsunenko T, et al. A core gut microbiome in obese and lean twins.Nature. 2009;457:480-484.Abstract

21. Goodman AL, Gordon JI. Our unindicted coconspirators: human metabolism from a microbialperspective. Cell Metab. 2010;12:111-116.Abstract

22. van Nood E, Vrieze A, Nieuwdorp M, et al. Duodenal infusion of donor feces for recurrent Clostridiumdifficile. N Engl J Med. 2013;368:407-415.Abstract

Medscape Cardiology 2013 WebMD, LLC

Cite this article: Beef, Microbes in the Gut, and Heart Disease. Medscape. Jun 19, 2013.
http://investor.liposcience.com/common/download/download.cfm?CompanyID=AMDA-ZIFX5&FileID=657183&FileKey=e4ea1b3d-b0ee-4260-9ebe-2a904ef82d9e&FileName=LPDX_News_2013_4_25_General_Releases.pdfhttp://investor.liposcience.com/common/download/download.cfm?CompanyID=AMDA-ZIFX5&FileID=657183&FileKey=e4ea1b3d-b0ee-4260-9ebe-2a904ef82d9e&FileName=LPDX_News_2013_4_25_General_Releases.pdfhttp://investor.liposcience.com/common/download/download.cfm?CompanyID=AMDA-ZIFX5&FileID=657183&FileKey=e4ea1b3d-b0ee-4260-9ebe-2a904ef82d9e&FileName=LPDX_News_2013_4_25_General_Releases.pdfhttp://investor.liposcience.com/common/download/download.cfm?CompanyID=AMDA-ZIFX5&FileID=657183&FileKey=e4ea1b3d-b0ee-4260-9ebe-2a904ef82d9e&FileName=LPDX_News_2013_4_25_General_Releases.pdfhttp://www.businesswire.com/news/home/20120905005255/en/LipoScience-Receives-FDA-Clearance-Vantera-Clinical-Analyzerhttp://www.businesswire.com/news/home/20120905005255/en/LipoScience-Receives-FDA-Clearance-Vantera-Clinical-Analyzerhttp://www.businesswire.com/news/home/20120905005255/en/LipoScience-Receives-FDA-Clearance-Vantera-Clinical-Analyzerhttp://www.medscape.com/medline/abstract/22412075http://www.medscape.com/medline/abstract/22412075http://www.medscape.com/medline/abstract/22412075http://www.medscape.com/medline/abstract/20071648http://www.medscape.com/medline/abstract/20071648http://www.medscape.com/medline/abstract/20071648http://www.medscape.com/medline/abstract/17183312http://www.medscape.com/medline/abstract/17183312http://www.medscape.com/medline/abstract/17183312http://www.medscape.com/medline/abstract/19043404http://www.medscape.com/medline/abstract/19043404http://www.medscape.com/medline/abstract/19043404http://www.medscape.com/medline/abstract/20674856http://www.medscape.com/medline/abstract/20674856http://www.medscape.com/medline/abstract/20674856http://www.medscape.com/medline/abstract/23323867http://www.medscape.com/medline/abstract/23323867http://www.medscape.com/medline/abstract/23323867http://www.medscape.com/medline/abstract/23323867http://www.medscape.com/medline/abstract/20674856http://www.medscape.com/medline/abstract/19043404http://www.medscape.com/medline/abstract/17183312http://www.medscape.com/medline/abstract/20071648http://www.medscape.com/medline/abstract/22412075http://www.businesswire.com/news/home/20120905005255/en/LipoScience-Receives-FDA-Clearance-Vantera-Clinical-Analyzerhttp://www.businesswire.com/news/home/20120905005255/en/LipoScience-Receives-FDA-Clearance-Vantera-Clinical-Analyzerhttp://investor.liposcience.com/common/download/download.cfm?CompanyID=AMDA-ZIFX5&FileID=657183&FileKey=e4ea1b3d-b0ee-4260-9ebe-2a904ef82d9e&FileName=LPDX_News_2013_4_25_General_Releases.pdfhttp://investor.liposcience.com/common/download/download.cfm?CompanyID=AMDA-ZIFX5&FileID=657183&FileKey=e4ea1b3d-b0ee-4260-9ebe-2a904ef82d9e&FileName=LPDX_News_2013_4_25_General_Releases.pdfhttp://investor.liposcience.com/common/download/download.cfm?CompanyID=AMDA-ZIFX5&FileID=657183&FileKey=e4ea1b3d-b0ee-4260-9ebe-2a904ef82d9e&FileName=LPDX_News_2013_4_25_General_Releases.pdf

gastric inflammation and cardiovascular disease

Documents