It may also improve body composition by reducing body fat and increasing muscle mass 21 , 22 , 23 , 24 , However, many studies show no effect at all 26 , 27 , In a review of 18 controlled trials, CLA was found to cause modest fat loss The effects are most pronounced during the first six months, after which fat loss plateaus for up to two years. According to this paper, CLA can cause an average fat loss of 0. Another review gathered that CLA caused about 3 pounds 1. While these weight loss effects may be statistically significant, they are small — and there is potential for side effects.
Though CLA supplements are linked to fat loss, the effects are small, unreliable and unlikely to make a difference in everyday life. Many long-term observational studies have assessed disease risk in people who consume larger amounts of CLA. Notably, people who get a lot of CLA from foods are at a lower risk of various diseases, including type 2 diabetes and cancer 31 , 32 , Additionally, studies in countries where cows predominantly eat grass — rather than grain — show that people with the most CLA in their bodies have a lower risk of heart disease However, this lower risk could also be caused by other protective components in grass-fed animal products, such as vitamin K2.
Of course, grass-fed beef and dairy products are healthy for various other reasons. Many studies show that people who eat the most CLA have improved metabolic health and a lower risk of many diseases.
However, the CLA found in supplements is made by chemically altering linoleic acid from vegetable oils. They are usually of a different form than the CLA found naturally in foods. Supplemental doses are also much higher than the amounts people get from dairy or meat.
As is often the case, some molecules and nutrients are beneficial when found in natural amounts in real foods — but become harmful when taken in large doses. Large doses of supplemental CLA can cause increased accumulation of fat in your liver, which is a stepping stone towards metabolic syndrome and diabetes 35 , 36 , Keep in mind that many of the relevant animal studies used doses much higher than those people get from supplements.
However, some human studies using reasonable doses indicate that CLA supplements may cause several mild or moderate side effects, including diarrhea, insulin resistance and oxidative stress Several animal studies have observed harmful side effects from CLA, such as increased liver fat. One review concluded that a minimum of 3 grams daily is necessary for weight loss Doses of up to 6 grams per day are considered safe, with no reports of serious adverse side effects in people 41 , Studies on CLA have generally used doses of 3.
However, these examples say that the evidence is inconsistent across the studies. There are no studies looking at the effects of CLA on bodybuilding specifically. A review of available research suggests that the benefits of taking CLA supplements alongside exercising vary. The researchers, however, do include several studies that showed CLA supplements could reduce body fat and improve lean body mass, which is the ratio of fat to body weight.
In one study, participants who took 1. The authors said that CLA might reduce fat deposition. Recent studies have questioned whether CLA-induced weight loss has the same benefits as traditional methods of weight loss, the latter being calorie restriction and exercise. One study compared two groups of obese mice with characteristics of human metabolic syndrome. To test weight loss, the researchers gave the first group of animals CLA supplements while putting the second group on a calorie-restriction diet.
The scientists studied the physical changes between the two groups. Both groups lost equal amounts of weight, though they had different physical changes:.
The study concluded that calorie restriction was a healthier form of weight loss than taking CLA supplements.
Atherosclerosis , or hardening of the arteries, is when plaque builds up in the arteries. This is a risk factor for heart disease. One study on obese mice suggested that taking CLA supplements could protect against atherosclerosis.
However, researchers need to do further studies before they know the true effects of CLA on atherosclerosis in humans. Animal products from ruminants, such as cows, goats, sheep, and deer contain CLA. These products include meat, milk, and cheese. The amount of CLA in animal products depends on farming techniques. Products from grass-fed animals contain more CLA than those from grain-fed animals.
Over recent decades, numerous studies have shown that grass-based diets improve fatty acid ratios, specifically increasing CLA and omega-3 content, and also increase the healthful antioxidant content in beef. Feeding animals plant sources of linoleic acid, such as sunflower, soybean or linseed oil, can also increase the amount of CLA in their milk fat. A popular method of consuming CLA-rich butter is bulletproof coffee , which combines coffee, oil, and butter.
The type of CLA in supplements is different from natural forms from animal products. To make supplements, manufacturers create CLA by chemically altering plant sources of linoleic acid. There are no established guidelines, but past studies show effects from at least 3 g a day. Studies on fat loss used between 3. Beyond this, studies so far are inconclusive about how much CLA people may consume. Dramatic results seen in animal studies required mice to consume large amounts of CLA for effects.
Also, there are few studies into long-term CLA supplementation. List of Partners vendors. Conjugated linoleic acid CLA is a fatty acid often marketed as a weight loss aid. Naturally found in dairy products and beef, CLA can be synthesized in the lab as a dietary supplement.
Proponents claim that CLA can reduce fat, build muscle, and increase energy and endurance. Others believe that CLA can enhance immune function while improving high cholesterol and blood pressure levels. Despite its popularity among some athletes, the evidence remains split on whether CLA can deliver on these promises.
Conjugated linoleic acid is found in a plethora of weight loss supplements, either on its own or co-formulated with other ingredients, such as caffeine or guarana.
While the supplement is mainly used for weight loss , CLA is believed by some to have other health benefits.
In the same year, another review published in Public Health Nutrition reported no difference between the body weight or composition of those who took CLA versus those who took a placebo.
What's more, a component of CLA supplements, known as trans,cis, was found to have a negative impact on blood sugar and could potentially contribute to the development of insulin resistance and atherosclerosis hardening of the arteries. So conflicting is the research that scientists have a tough time even suggesting how CLA is meant to work. While CLA is believed to suppress appetite, few studies have shown this to have any effect on weight or body fat composition.
Based on current evidence, a review published in Nutrition and Metabolism concluded that CLA offered no "promising or consistent health effects so as to uphold it as either a functional or medical food. Beyond its use in weight loss, proponents of CLA supplementation believe that it can enhance athletic performance by stimulating testosterone production in the Leydig cells of the testicles.
While it is true that CLA has this effect, the level of stimulation rarely translates to increased energy expenditure. In fact, review in the Journal of the International Society of Sports Nutrition found inconclusive evidence on many claims made by proponents of CLA supplementation on athletes.
Other health benefits are also largely unsupported, including CLA's use in treating diabetes, the common cold, allergic rhinitis hay fever , or asthma. Similarly, while an increased intake of CLA was once linked to a reduction in breast cancer risk, a review of studies was unable to show any association between CLA levels in breast tissue and the risk of cancer, metastasis, or death.
Where CLA may be beneficial is as adjunctive therapy for high blood pressure. When used with Altace ramipril , CLA was shown to achieve better control of hypertension compared to Altace alone, according to a study from China.
Conjugated linoleic acid supplements are generally considered safe if taken as prescribed. CLA is mainly metabolized in the liver. On rare occasion, CLA may cause liver toxicity usually in people with underlying liver disease. Large doses can also trigger the accumulation of fat in the liver, leading to fatty liver disease, diabetes, and metabolic syndrome. Conjugated linoleic acid may also slow blood clotting. Taking a CLA supplement along with an anticoagulant "blood thinners" or nonsteroidal anti-inflammatory drug NSAID can further enhance this effecting, leading to easy bruising and bleeding.
Conjugated linoleic acid supplements are typically produced as a gel cap and filled with either sunflower or safflower oil. CLA is classified by the U. Food and Drug Administration as GRAS "generally regarded as safe" and typically prescribed at between 3 grams and 6 grams per day. Doses greater than 6 grams may increase the risk of side effects.
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