CLA: A Trans Fat that’s Actually Good for You?
We’ve heard of good carbs and bad carbs. And we’ve definitely heard about good fats and bad fats. And we all know that trans fats are the worst fats of all. Or are they?
Turns out, there are also good and bad trans fats. Or, more specifically, one good trans fat. Oh yes, it’s most definitely true.
Unlike most of the trans fats we hear about that lead to heart disease, type-2 diabetes, and obesity, this trans fat has the exact opposite effect. It has been shown to help promote weight loss and even protect us against cancer.
Let’s take a closer look at this miracle trans fat. What is it? How is it different from its more villainous relatives? And, more importantly, does the research support the claims?
And The Good Trans Fat Is…
Conjugated linoleic acid, or CLA, is the surprising trans fat we are talking about.
Cows and other cud-chewing animals such as sheep, goats, and deer have a special bacteria in their stomachs that convert linoleic acid (a type of fatty acid) into CLA.
Thus, when we eat the food products of these animals, as the meat itself or dairy products, we ingest CLA through our diet.
In other words, nature is creating this particular fatty acid and we consume it by consuming the animal or its milk.
This is completely different than the more common trans fats, which tend to be man-made. Unlike the cow or sheep using bacteria to convert linoleic acid into CLA, someone in a laboratory is taking otherwise healthy oils and hydrogenising them into trans fats.
The end result is hydrogenated or partially hydrogenated oils. Or, in more direct terms, margarine, candy bars, snack foods, and French fries. Basically any junk foods and fried delicacies.
This is a far cry from a naturally occurring trans fat like CLA.
But can this trans fat actually be good for you? Many researchers would say yes.
How It Works…
Advocates of conjugated linoleic acid (CLA) claim that the nutrient helps to reduce body fat, increase lean muscle mass, and lose weight. Moreover, they claim that conjugated linoleic acid helps you transform your love handles into a six-pack by increasing your fat-burning capabilities.
While this may or may not be accurate, the truth is, no one knows exactly how conjugated linoleic acid works. However, researchers do hypothesize that it works on several pathways.
We know that adequate amounts of CLA are needed to convert dietary fat to energy. Therefore, it appears to decrease the amount of fat stored after eating, increase the rate of fat breakdown in fat cells, and decrease the total number of fat cells.
But rather than guessing and supposing, let’s see what the research actually says.
Exploring the Research…
Much of the positive research surrounding conjugated linoleic acid includes animal studies, specifically mice. In the first study1, male mice were divided into four groups:
- High-fat diet only
- High-fat diet with CLA
- Low-fat diet only
- High-fat diet with CLA
Researchers discovered that, regardless of diet, the mice that received the conjugated linoleic acid had a significant reduction in body fat (ranging from 43 to 88 percent), most of which was in the abdominal area. (Most of us could use that, no?) They also hypothesized that the reason for the reduction was due to, in part, increased metabolic rate and decreased appetite.
A second mouse study2 looked at conjugated linoleic acid dosage. Researchers gave five groups of mice differing dosages of CLA for 39 days. They found that those mice taking the three largest dosages had significantly less body weight than the control group. They also found that those mice taking the conjugated linoleic acid had increased the muscle mass as well.
But What About in Humans?
Now don’t get us wrong; animal studies can be both interesting and promising. However, they do raise the question as to whether CLA works equally well in humans. And the answers appear to be mixed.
A 2000 study from the Journal of Nutrition3 indicates that it does. Here, the researchers performed a randomized, double-blind, placebo-controlled study (the “gold standard” in research) with 60 overweight or obese participants. They were divided into five groups, with one group receiving a placebo and the others receiving a range of daily conjugated linoleic acid dosages (1.7 g, 3.4 g, 5.1 g, or 6.8 g).
After 12 weeks, those who took 3.4 grams per day and 6.8 grams per day enjoyed body fat reductions as compared to the other groups, including the 5.1 gram group. The researchers did not provide a hypothesis for why this occurred.
Does this seem odd, that the highest and second lowest doses were effective but not the middle dose? We thought so too and would love to see the study repeated with just those three doses. If the results are the same, it would be nice to have the researchers at least attempt to hypothesize why.
Separately, a 2003 double-blind, placebo-controlled study, also from the Journal of Nutrition4, supports CLA’s ability to reduce body fat. Researchers divided 21 adults with type-2 diabetes into two groups. The first group was given a placebo and the second group was given a conjugated linoleic acid supplement.
After eight weeks, 82 percent of those taking the CLA saw a reduction in their fasting glucose levels, while only 20 percent of the placebo group had a reduction in their glucose levels. Additionally, those in the conjugated linoleic acid supplement group lost an average of 3.5 pounds, while those on the placebo neither gained nor lost weight. Plus, those taking the CLA also had a reduction in their levels of leptin, a hormone associated with both weight gain and fat storage.
Is the Celebration Well-Founded?
While all of these studies appear to lean in favor of conjugated linoleic acid truly demonstrating an ability to aid in weight loss and fat reduction, there are a few concerns.
The animal studies speak for themselves, in that they are just that: animal studies. So they are not necessarily reflective of how the nutrient performs in humans.
As for the human studies, while they do employ the gold standard research protocol, they both have a fairly low number of participants, as well as a relatively brief study duration (12 weeks and 8 weeks respectively). And, according to a 2006 study from the American Journal of Clinical Nutrition5, the short duration of the studies may be a flaw.
In that study, 122 obese individuals were monitored for a full year. Half of the group took 3.4 grams of CLA a day, while the second group took a placebo. At the end of the year, there was no significant difference in either body weight or body fat between the two groups.
Hmmm. This does raise a question about the effectiveness of conjugated linoleic acid. However, while this study was also double-blind and placebo-controlled, there are two possible critiques that could be raised.
First, it did employ a slightly lesser dosage of conjugated linoleic acid (3.4g). Also, it did not discount that conjugated linoleic acid works in the short-term (as the other studies found).
What the study does show is that, when diet and exercise are equal, long-term CLA use was not statistically significant.
But Wait, There’s More…
In addition to possibly reducing body weight and body fat, conjugated linoleic acid has also been associated with reducing tumor growth and development of breast cancer in animals6. Conjugated linoleic acid supplementation has also been associated with increased immune function.
In fact, in the American Journal of Clinical Nutrition study that found the nutrient was not associated with weight loss or body fat reduction when taken for a year, it was found that those taking CLA had a significant increase in their leukocyte count, also known as white blood cells, which is commonly associated with a strong immune system.
Fortunately, the only adverse side effects associated with conjugated linoleic acid are occasional upset stomach and diarrhea. Which side effect would you rather deal with…possible bellyache and diarrhea or a stronger immune system and possible weight loss? That seems to be a no-brainer.
What To Make of All This…
Overall, the research surrounding CLA as a healthy trans fat does appear to be accurate. It clearly helps to reduce both weight and body fat, at least when taken over a two- to three-month period of time. And its cancer and immune properties are promising in the least!
If you do decide to include conjugated linoleic acid in your health regimen, your best bet is to follow Hippocrates’ advice and “let food be your medicine.” As we indicated early on, grass-fed beef and dairy products from grass-fed cows are rich in conjugated linoleic acid.
And remember, the key is “grass-fed.” In fact, a study from the Journal of Dairy Sciences7 found that cows that are grass-fed, pasture-raised had twice as much conjugated linoleic acid in their milk fat than those cows that were fed a conventional, grain-based diet. You simply will not receive the same CLA benefits from conventionally raised, corn-fed, toxic cattle.
Because it would be next to impossible (and probably ill-advised) to eat the amount of beef and dairy products that you would need to reach the therapeutic doses of CLA, you may need to augment your diet with a conjugated linoleic acid supplement. However, like all things in life, not all CLA is the same.
Much of the research has been done using a form of conjugated linoleic acid called Tonalin. Therefore, should you chose to use a CLA supplement, you may want to chose a product that contains the Tonalin form. And, based on the research, you’ll want to take at least 3.5 grams a day.
There are several companies that have been licensed to market Tonalin. Look for a manufacturer that uses good manufacturing practices (GMP) for the product and be sure you can find all ingredients contained in the product before purchasing.
If you chose to use a conjugated linoleic acid that is not Tonalin, be sure to research their particular form of the nutrient. Is it safe? Has it been through clinical trials?
Finally, be sure the product you choose is free of preservatives, fillers, binders, excipients, flow agents, shellacs, coloring agents, gluten, yeast, lactose, and other allergens. Ideally you’ll also be able to find independent analysis done by a third party to verify the active ingredients and identify any contaminants.
As you can see, all foods—not even all trans fats—are the same. Keep questioning, asking questions, and seeking answers. Being an informed consumer is the best way to protect your health. And if you find surprising solutions like CLA along the way, all the better!
1West, DB, et al. “Effects of conjugated linoleic acid on body fat and energy metabolism in the mouse.” Am J Physiol. 1998 Sep;275(3 Pt 2);R667-72.
2DeLany, JP, et al. “Conjugated linoleic acid rapidly reduces body fat content in mice without affecting energy intake.” Am J Physiol. 1999;276(4 Pt 2):R1172-9).
3Blankson, H, et al. “Conjugated linoleic acid reduces body fat mass in overweight and obese humans. J Nutr. 2000;130(12):2943-8.
4Belury, MA, et al. “The conjugated linoleic acid (CLA) isomer, t10c12-CLA, is inversely associated with changes in body weight and serum leptin in subjects with type 2 diabetes mellitus.” J Nutr. 2003;133(1):257S-60S.
5Larsen, TM, et al. “Conjugated linoleic acid supplementation for 1 y does not prevent weight or body fat regain.” Am J Clin Nutr. 2006 Mar;83(3):606-12.
6Visonneau, S, et al. “Conjugated linoleic acid suppresses the growth of human breast adenocarcinoma cells in SCID mice. Anticancer Res. 1997;17(2A):969-73.
7Kelly, ML, et al. “Effect of intake of pasture on concentrations of conjugated linoleic acid in milk of lactating cows.” J Dairy Sci. 1998 Jun;81(6):1630-6.
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