Carnitine is known to play a major role in the utilization of fat for fuel. As such, supplemental carnitine is sometimes thought to improve performance in sports requiring a large aerobic component. Carnitine might also be beneficial for people who are in the process of losing weight.

Study Design

In the study, 21 active men were divided into two groups. One group supplemented two grams of carnitine every day for two weeks. The other group took a convincing facsimile for the same amount of time. At the end of the two weeks they ran fourteen kilometers (a little over 8.6 miles). Blood was drawn before supplementation, just before the workout, shortly after the workout, and then again a day later.

The researchers were looking for three primary things in the blood test results:

• Antioxidant status
• Oxidative stress to lipids by free radicals
• Muscle tissue damage

Oxidative stress and muscle tissue damage are the results of physical stress. Antioxidant status is one of the body’s indicators that it is dealing with stress. The researchers wanted to know if carnitine consumption affected these factors.

Results

Two weeks of carnitine consumption was an effective protocol. The day after the workout, free radical status and muscle damage were significantly lower in the group taking carnitine than in the placebo group. Antioxidants were also higher in the carnitine group, both before and after exercise and on the day after the workout. These results indicate that carnitine supplementation may assist in recovery from workouts and reduce the chance of overtraining.

Supplements vs. Food Sources

In this study, carnitine was investigated in supplement form. However, it is believed that the body might absorb food-sourced carnitine more easily. Although food sources tend to contain less carnitine than a supplement, the higher absorption may make it a more effective source. If so, then foods high in carnitine, like red meat, might be an even better option.

The body can synthesize carnitine, which means it is not a nutritionally essential nutrient, so you might have heard that supplementing with carnitine is not necessary. However, for people who exercise a lot, the body’s ability to synthesize carnitine may be taxed. This is particularly true for people who do a lot of aerobic exercise or those who are trying to lose weight. As such, consuming L-carnitine, either in supplemental form or in red meat, might assist your goals.

Either way, carnitine has proven to be a valuable nutrient for athletes. One way or another, ensure that you are getting adequate quantities. A dose of two grams per day was used in this study. Although this is well above the amount you would get from your diet, it may be needed due to low absorption. Getting a quarter of that via diet should be more than adequate.

References:

1. Khadijeh Parandak, et. al., “The Effect of Two-Week L-Carnitine Supplementation on Exercise –Induced Oxidative Stress and Muscle Damage,” Asian Journal of Sports Medicine, 5:2, 2014

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Despite some claims that carnitine is unhealthy, it is of extreme importance for human life. Supplemental carnitine seems to be an ergogenic aid as well, meaning it may boost athletic performance. However, until now there was little information on the dose-response of carnitine. In other words, we didn’t know if more carnitine worked better. With many biological components there’s a point of diminishing returns, so researchers performed a study, published recently in the Journal of Strength and Conditioning, to examine the dose-response of carnitine on performance.

Now don’t be fooled by the phrase non-essential amino acid. In nutrition the term essential has a specific meaning that can be confusing. To you and me, when something is essential, that means its presence is required to achieve some end. However, to a nutritionist, when something is essential that means it is required in the diet, but it isn’t a statement about its importance. Because carnitine can be synthesized (made inside the body without being consumed) from lysine and methionine, two other amino acids, it is not considered nutritionally essential.

However, as pointed out earlier, carnitine is required for health, and theoretically it is possible to interfere with the body’s ability to produce carnitine. Thankfully, carnitine is also present in the diet and supplements, making it what some nutritionists may call semi-essential, or partially required in the diet for optimal health.

So it’s no surprise the researchers in this study wanted to know if more carnitine in the diet – in this case, taken as a supplement – would boost cardio performance. Since dietary carnitine may be necessary to prevent the exhaustion of its synthesis in the body, more might be better to allow for a greater fat burn.

Interestingly, the researchers concluded there was no statistically significant difference between taking 3g of carnitine and 4g of carnitine, the two doses used in this study. However, despite this conclusion, when you look at the data this doesn’t seem to be the case. Participants who received 3g of carnitine reached a statistically significant improvement in performance – as measured by looking at the levels of fatigue markers for each speed – over those who received a placebo at every running speed tested. Participants who received 4g only performed better at the two fastest speeds than those receiving the placebo.

It should also be noted that there were definitely trends that did not reach significance, but seemed clear nonetheless. More or less across the board, when taking carnitine at any dose, athletes could maintain faster speeds with less fatigue than with placebo. Additionally, a dosage of 3g of carnitine seemed consistently better than a dosage of 4g.

While I agree with the researchers’ ultimate call for more research, this study did show that carnitine improves performance. I would also say their results suggest there is a dose relationship, but not like we may think. In this case, the slightly lower dosage of 3g of carnitine might be better than 4g, but we’ll need more and better research to find out what dose works the best.

References:

1. Erikoglu Orer Gamze, et. al., “The Effects of Acute L-Carnitine Supplementation on Endurance Performance of Athletes,” Journal of Strength and Conditioning Research, DOI: 10.1097/JSC.0000000000000204.

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The post Less Is More: New Studies Investigate Carnitine Dose-Response appeared first on Breaking Muscle.

I’ve always just waved off reports of red meat being linked to heart disease as a matter of fact. Sure if you eat a lot of bad food, including fatty, poorly-raised red meats you’re going to get sick at some point. That’s not advanced science, that’s just common sense. The big difference in this study is the link between lean red meat and heart disease. That’s right, even the non-fatty stuff that most of us think is fine – especially the paleo diet followers among us.

But wait, all this talk from researchers about red meat seems to just be an attempt at media attention. And it worked, because sure enough the Times picked up the story. What the research actually found was a link between the amino acid L-carnitine and heart disease. Red meat just so happens to be high in carnitine. If true, however, carnitine supplements, carnitine containing drinks, and really anything with carnitine could be an issue as well.

While the media didn’t give this point a ton of attention, for readers of Breaking Muscle, it might be much more important. I don’t know about you, but I love my red meat, and I have a bottle of carnitine caps close at hand as well. Carnitine is a required component of the fat-burning process in the body, so it is very important, and many athletes take it as a performance enhancer or contributor to weight loss.

Apparently, carnitine is metabolized by intestinal bacteria into a chemical called TMAO. TMAO alters cholesterol transport and metabolism, and voila, heart disease over time. Indeed the researchers used antibiotics and a vegan participant to test the theory, and in both cases the TMAO levels remained low, even with consumption of high dietary carnitine. This is because in both cases the microflora of the intestine didn’t exist to create the TMAO.

So does this mean red meat is out? Let’s not be so hasty. With red meat consumption having a long precedent in human history, we should be very demanding of any research indicating it isn’t healthy for us. I’m not sure this fits the bill.

We might still have a selection bias here. Just because carnitine metoblizes into TMAO doesn’t automatically mean it is bad for you. Carnitine is required for human life, and the human part of the study focused on meat consumption. It could simply be that the vegetarian participants led a healthier (non-average) life. However, mice supplementing with carnitine did also exhibit greater risk for heart disease. Happily, researchers found that circulating carnitine only correlated with heart disease if TMAO was also present. As such, it seems likely that high carnitine intake might not be an issue if it is utilized rather than metabolized.

I do love a good steak, and I’m not convinced it is bad for you. I think more research is needed on the variables before we just oust the red meat from our diets, but I’m going to keep an open mind on this one.

References:

1. Robert Koeth, et. al., “Intestinal microbiota metabolism of l-carnitine, a nutrient in red meat, promotes atherosclerosis,’ Nature Medicine (2013).

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