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April 2013

Topics:

Vitamin D and atrial fibrillation
Carnitine and heart risks
Lycopene and heart risks
Gazpacho reduces hypertension
[Practical guidelines are now included at the end of each article]

Vitamin D and atrial fibrillation

A patient recently informed me of a study showing that excess vitamin D was linked to a heart arrhythmia called atrial fibrillation. The public warnings about taking too much vitamin D were misguided if they relied on the reporting of data from this study or the headlines that it generated. The report was from a paper presented in November of 2011, at the annual meeting of the American Heart Association, by Dr. Jared Bunch, from the Heart Institute of the Intermountain Medical Center in Murray, Utah. (Smith MB, et al., Vitamin D excess is significantly associated with risk of atrial fibrillation. American Heart Association 2011 Meeting. 2011; 124: A14699.)

The NBC News headline read: “Taking too much vitamin D can raise the risk of your heart beating too fast and out of rhythm…” The title from the Heart Institute itself said: “Study links excess vitamin D levels with onset of atrial fibrillation.” Anyone reading these headlines would think they had to be extremely careful about taking vitamin D supplements. Not surprisingly, those with the lowest levels of vitamin D had increased risks for diabetes, hypertension, congestive heart failure, and kidney failure.

Indeed, the Heart Institute researcher was quoted in the press release as saying specifically that “There are both benefits and harm to taking vitamin supplements of all kinds…” How he arrives at this position is not clear, since most vitamin supplements (including vitamin D) are quite safe even at very high doses. If you look at the details of the report, it turns out that the headlines are totally unjustified by the data.

The researchers analyzed the vitamin D levels of 132,000 patients at their medical center. They reported that the risk of new onset atrial fibrillation was tripled when vitamin D levels were “high,” but they went on to be more specific. They categorized patients by their vitamin D level as deficient if they were below 20 ng/ml, low-normal if they were from 21 to 40 ng/ml, normal if their serum level was 41 to 80 ng/ml, high/normal if they were from 81 to 100 ng/ml, and excessive if they were above 100 ng/ml. they then correlated these vitamin D levels with atrial fibrillation (a condition in which the atria quiver instead of beating and fail to generate the usual normal heartbeat). The group with the lowest incidence of atrial fibrillation was the group with the level of vitamin D from 81-100 ng/ml. They had half the rate of atrial fibrillation compared to those with the lowest level of vitamin D (although the differences were not statistically significant except for those with vitamin D levels over 100 ng/ml).

In spite of the scary headlines, the only group to show an increase of atrial fibrillation was the one with serum levels in the “excessive” range (over 100 ng/ml). None of the other groups showed any increase of atrial fibrillation. The headlines are misleading (as is the comment on vitamin supplements being harmful) because it is very difficult to achieve serum levels in that excessive range even with high doses of vitamin D. My patient’s other doctor was astonished that he was taking 6000 IU of vitamin D, and he was sure it was a toxic dose. He did a blood test, and my patient turned out to be at 37 ng/ml, which is the low normal range. I was taking 5000 IU daily back in November, and my vitamin D level was just 47 ng/ml. I have increased my dose to 10,000 IU on most days and 5000 IU on others.

Vitamin D has many benefits, including those for the heart. In a new study, researchers evaluated the effect of vitamin D on congestive heart failure in 100 patients. Only 6 percent of them had adequate vitamin D levels. Supplements raised their levels from 12.6 to 54.5 ng/ml. The supplements decreased their CRP levels (a sign of inflammation and a risk factor for heart disease), and it significantly improved their New York Heart Association (NYHA) class for heart failure as well as their 6-minute walk distance. (Amin A, et al., Can vitamin D supplementation improve the severity of congestive heart failure? Congest Heart Fail. 2013 Mar 21. doi: 10.1111/chf.12026. [Epub ahead of print

Practical guidelines:

Consider taking 2000 IU of vitamin D daily and getting your blood level checked (you can have blood drawn by your doctor for this, or for $65 you can do a home test with a kit for a finger stick, putting a drop of blood on provided blotting paper, and sending it to the lab (https://vitamindcouncil.zrtlab.com). If your level is low (below the 41 to 80 ng/ml recommended range), you can always increase your supplementation.

Carnitine and heart risks

L-carnitine is a dietary amino acid found primarily in meats, but it is also available in tempeh, wheat, avocados, asparagus, and peanut butter. You also synthesize carnitine from lysine and methionine, although with age the rate of synthesis declines. Carnitine is essential for transporting fatty acids into the mitochondria for metabolism into energy, and the heart muscle is very rich in carnitine. Patients with heart disease often take supplements of carnitine because of documented benefits for heart failure, angina, improved exercise tolerance, and decreased mortality. Recently carnitine in meat has been associated with an increased level of one heart disease risk factor. This made headlines (again), and it might scare people away from taking carnitine supplements, but they would be missing out on the documented benefits. (Koeth RA, et al., Intestinal microbiota metabolism of l-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med. 2013 Apr 7. doi: 10.1038/nm.3145. [Epub ahead of print])

Consuming meat increases the population of gut bacteria that produce trimethylamine-N-oxide (TMAO) from choline. Most of the research was done with animal models, which does not always translate to humans, but in a small study of humans, those who were vegetarian or vegan produced far lower levels of TMAO. In the mice, adding carnitine to their diets as a supplement started to increase the levels of bacteria that produce TMAO. Whether this happens in humans is not clear.

One author of this study, Stanley Hazen, was interviewed on National Public Radio’s Talk of the Nation-Science Friday. He noted that vegetarians do not have the same risks as meat eaters for the development of heart disease. He did accept that this could be for a number of reasons, and that the TMAO is related to the risk created by increased cholesterol levels.

In the comments on the NPR website, the benefits of carnitine supplements for the heart were noted, but Dr. Hazen dismissed them, saying “research evidence on the benefits of L-Carnitine has shown no differences in death rates. Exactly what are the benefits to heart muscle function while alive remains unclear to me, but I'm not studied up on it; it seemed obscure.” Apparently, he is taking his lack of clarity and converting it to factual conclusions. At least he admits that he is “not studied up on it” so why is he making such firm pronouncements that carnitine is useless and may be harmful? His study also did not show mortality data, just risk factors.

In a systematic review and meta-analysis of 13 studies on a total of 3629 subjects who had had a myocardial infarction, carnitine supplements were associated with a 27 percent reduction in mortality. They were also associated with a 65 percent reduction in ventricular arrhythmias, and a 40 percent reduction in angina symptoms. (Dinicolantonio JJ, et al., L-carnitine in the secondary prevention of cardiovascular disease: systematic review and meta-analysis. Mayo Clin Proc. 2013 Apr 15. pii: S0025-6196(13)00127-4. doi: 10.1016/j.mayocp.2013.02.007. [Epub ahead of print])

An earlier review showed that administration of 1.5 to 6 grams of carnitine per day to heart patients (heart attacks, angina, and congestive heart failure) led to fewer deaths, and less heart failure. Carnitine also appears to improve exercise tolerance and oxygen consumption in moderate to severe heart failure. (Pauly DF, Pepine CJ, The role of carnitine in myocardial dysfunction. Am J Kidney Dis. 2003 Apr;41(4 Suppl 4):S35-43.) Other studies have shown that supplements of carnitine can improve walking distance in people who have intermittent claudication (pain in the legs on walking due to hardening of the arteries). (Brevetti G, et al., Carnitine-related alterations in patients with intermittent claudication: indication for a focused carnitine therapy. Circulation. 1996 May 1;93(9):1685-9.) Claudication is common in diabetic arterial disease. It is clear that carnitine provides cardiovascular benefits in a variety of conditions.

Practical guidelines:

Until there is serious evidence of harm from carnitine (as opposed to the known harm from meat consumption), I would recommend supplements of 500 to 2000 mg twice per day for anyone with a heart problem. We always base our health practice decisions on imperfect information. Research in health and medicine is constantly evolving. If we were to wait for “perfect” information before we make any decisions related to our health practices, we would never make any decisions at all. The weight of the evidence right now is that carnitine is beneficial for the heart.

Lycopene and heart risks

Lycopene is a red plant pigment in the carotenoid family of nutrients. It is commonly known to be found in tomatoes, but it is even more prevalent in watermelon, pink and red grapefruit, and red navel oranges (a slice of watermelon has 3 to 4 times as much lycopene as a fresh tomato). It is an antioxidant with a number of health benefits. A recent study of lycopene intake shows an inverse relationship with cardiovascular disease. (Jacques PF, et al., Relationship of lycopene intake and consumption of tomato products to incident CVD. Br J Nutr. 2013 Jan 15:1-7. [Epub ahead of print])

Subjects with the highest lycopene intake had a 17 percent reduction in overall cardiovascular disease incidence compared to those with the lowest lycopene intake. For coronary disease the risk reduction was 26 percent. Earlier studies showed that low serum lycopene is associated with thickening of the carotid artery, an early stage of atherosclerosis. Also, a supplement of 30 mg of lycopene led to a reduction in exercise-induced asthma.

Food content of lycopene is not always directly related to serum levels. Absorption is affected by processing (tomato sauce and juice have higher levels of lycopene than fresh tomatoes because cooking and juicing release lycopene from the cell walls). A tomato has about 4 mg of lycopene. A cup of tomato juice may have 25 mg of lycopene. A slice of watermelon has about 15 mg, and a pink grapefruit has about 5 mg.

Practical guidelines:

Try to eat a wide variety of whole, natural foods, including those with high lycopene content, and consider taking a supplement of 5 to 30 mg per day if you do not get adequate amounts from your diet.

Gazpacho reduces hypertension

One way to get lycopene and many other nutrients is to eat the uncooked Mediterranean soup called gazpacho. Its composition varies, but typically contains a tomato base with additional onion, garlic, diced cucumbers, sweet peppers, cilantro, lime juice, and cayenne pepper (depending on how spicy you like it). It may also contain minced horseradish for an additional flavor boost.

In a Mediterranean population, a study of 3995 subjects with high cardiovascular risk (based on blood pressures) showed that those who consumed the most gazpacho had the lowest blood pressures. For each 250 g/week consumption of gazpacho the researchers found a 15 percent reduction in the prevalence of hypertension. Those with the highest consumption had a 27 percent lower incidence of hypertension compared with those who did not consume any gazpacho. (Medina-Remón A, et al., Gazpacho consumption is associated with lower blood pressure and reduced hypertension in a high cardiovascular risk cohort. Cross-sectional study of the PREDIMED trial. Nutr Metab Cardiovasc Dis. 2012 Nov 10. pii: S0939-4753(12)00181-0. doi: 10.1016/j.numecd.2012.07.008. [Epub ahead of print])

Practical guidelines: Well, this is easy: just eat more gazpacho. It is a delicious cold soup that is just perfect for hot summer days.

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Information herein is not medical advice or direction. All material in this newsletter is provided for information only. Its contents should not be used to provide medical advice on individual problems. Consult a health care professional for medical or health advice.

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