CLA

What is CLA?

Conjugated Linoleic Acid (CLA) is a naturally occurring fatty acid found primarily in meat and dairy products from ruminant animals like cattle and sheep. CLA belongs to the omega-6 fatty acid family and exists in multiple forms, with the two most common being cis-9, trans-11 CLA and trans-10, cis-12 CLA. Unlike many other fatty acids, CLA contains conjugated double bonds, giving it unique chemical properties and potential biological effects. While the body can produce small amounts of CLA from linoleic acid, dietary intake represents the primary source for most people.

CLA supplements typically contain a mixture of different CLA isomers, often derived from safflower oil through industrial processing. The concentration and ratio of specific CLA isomers can vary significantly between products, which may influence their biological effects.

Health benefits & uses

Body composition and weight management (Limited evidence): Some studies suggest CLA supplementation may modestly reduce body fat and increase lean muscle mass. However, results have been inconsistent, with many high-quality trials showing minimal effects on weight loss or body composition in humans.

Cardiovascular health (Limited evidence): Preliminary research indicates CLA might influence cholesterol levels and reduce inflammation markers. However, some studies have shown mixed results, with certain CLA isomers potentially having adverse effects on cardiovascular risk factors.

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Immune system support (Limited evidence): Animal studies suggest CLA may enhance immune function and reduce inflammatory responses, but human clinical data remains limited and inconclusive.

Cancer prevention (Limited evidence): Laboratory and animal studies have shown promising anti-cancer properties of CLA, particularly against breast and colon cancers. However, human studies are lacking, and this potential benefit requires further investigation.

How it works

CLA appears to influence metabolism through multiple pathways. It may affect the activity of enzymes involved in fat storage and breakdown, particularly hormone-sensitive lipase and lipoprotein lipase. CLA also appears to influence the expression of genes related to fat metabolism and may reduce the activity of fatty acid synthase, an enzyme involved in fat production.

The different CLA isomers appear to have distinct mechanisms of action. The cis-9, trans-11 isomer is associated with potential anti-inflammatory and anti-carcinogenic effects, while the trans-10, cis-12 isomer is more strongly linked to changes in body composition and metabolic effects.

Dosage

There is no established Recommended Dietary Allowance (RDA) or Upper Limit (UL) for CLA, as it is not considered an essential fatty acid. Clinical studies have typically used doses ranging from 1.5 to 6 grams per day, often divided into multiple doses taken with meals.

Common supplemental dosing ranges include:

• General health: 1-3 grams daily
• Body composition goals: 3-6 grams daily

It’s important to consult with a healthcare provider before starting CLA supplementation, particularly at higher doses, as optimal dosing depends on individual factors and health goals.

Food sources

Natural dietary sources of CLA include:

• Grass-fed beef and lamb (higher CLA content than grain-fed)
• Full-fat dairy products (milk, cheese, butter, yogurt)
• Eggs from pasture-raised hens
• Turkey and chicken (smaller amounts)

Grass-fed animal products typically contain 2-5 times more CLA than conventional products. The average dietary intake of CLA is approximately 150-200 mg per day for most people, significantly lower than amounts used in research studies.

Safety & side effects

CLA supplementation is generally well-tolerated by most healthy adults when used appropriately. Common side effects may include:

• Digestive upset, including nausea and diarrhea
• Fatigue
• Headache
• Potential insulin resistance with prolonged high-dose use

Some studies have raised concerns about potential adverse effects on liver function and insulin sensitivity with certain CLA isomers, particularly trans-10, cis-12 CLA, when used at high doses for extended periods.

Interactions

CLA may interact with certain medications and supplements:

• Blood thinning medications: CLA may enhance anticoagulant effects
• Diabetes medications: Potential interactions with blood sugar control
• Other omega fatty acids: May compete for absorption and metabolism
• Fat-soluble vitamins: High doses might interfere with absorption

Taking CLA with meals containing fat may improve absorption and reduce digestive side effects.

Who should be cautious

Certain individuals should exercise caution with CLA supplementation:

• People with diabetes or insulin resistance
• Individuals with liver disease
• Those taking blood-thinning medications
• Pregnant or breastfeeding women
• People with bleeding disorders
• Those scheduled for surgery (discontinue 2 weeks prior)

Frequently asked questions

Is CLA effective for weight loss?

Research shows mixed results for CLA and weight loss. While some studies suggest modest fat loss, the effects are generally small and inconsistent. CLA should not be considered a primary weight loss strategy.

How long does it take to see results from CLA?

Most studies that showed benefits observed changes after 6-12 weeks of consistent supplementation. However, individual responses vary, and not everyone will experience noticeable effects.

Can I get enough CLA from food alone?

Typical dietary intake provides much less CLA than amounts used in research studies. While increasing consumption of grass-fed animal products can boost CLA intake, supplementation may be necessary to achieve research-level doses.

Are there different types of CLA supplements?

Yes, CLA supplements vary in their isomer composition. Some contain mixed isomers, while others are enriched in specific forms. The ratio of different CLA isomers may influence effectiveness and side effects.

Should I take CLA with food?

Yes, taking CLA with meals containing fat can improve absorption and reduce potential digestive side effects. This also helps ensure better utilization of the supplement.

References

References

1. Onakpoya IJ, Posadzki PP, Watson LK, Davies LA, Ernst E. The efficacy of long-term conjugated linoleic acid (CLA) supplementation on body composition in overweight and obese individuals: a systematic review and meta-analysis of randomized clinical trials. Eur J Nutr. 2012;51(2):127-134. doi:10.1007/s00394-011-0253-9
2. Dilzer A, Park Y. Implication of conjugated linoleic acid (CLA) in human health. Crit Rev Food Sci Nutr. 2012;52(6):488-513. doi:10.1080/10408398.2010.501409
3. Lehnen TE, da Silva MR, Camacho A, Marcadenti A, Lehnen AM. A review on effects of conjugated linoleic acid (CLA) upon body composition and energetic metabolism. J Int Soc Sports Nutr. 2015;12:36. doi:10.1186/s12970-015-0097-4

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