Articles

Conjugated Linoleic Acid (CLA)

Introduction

Bearing a close chemical resemblance to linoleic acid, research indicates that conjugated linoleic acid may also offer a number of health benefits. These include possible enhancement of immunity, as well as potential protection from cancer and heart disease. CLA may also stimulate growth of muscle tissue while promoting fat loss.

Small amounts of CLA occur in most kinds of meat while slightly larger concentrations occur in dairy products. These days, foods that formerly contained substantial amounts of CLA do not contain enough of the nutrient to make them acceptable sources. Since the 1960s, the CLA content of meat and dairy products has declined dramatically. Ruminants (beef, lamb and veal) used to contain substantial amounts of CLA in their muscle tissue, but switching these animals from pasture land (grass diets) to feedlots where they are primarily fed grain has resulted in approximately a 75% decline in these animals.

It has been speculated that the dramatic decline in available CLA in American diets may be linked to increased rates of cancer, heart disease, and obesity.

Dosage Info

Dosage Range

Most of the research with CLA to date has been conducted in animals, often with relatively large doses. Until human trials are conducted, the appropriate dosage range for humans is unknown. Recommendations on available CLA supplement products seems to be in the range of two to four grams daily.

Most Common Dosage

The most common dosage cannot be determined at this time.

Dosage Forms

Gelatin capsules

Interactions and Depletions

Interactions

Reported Uses

Recent research suggests that CLA may provide a previously unrecognized form of antioxidant defense from harmful free radicals. (1) Studies further suggest that CLA may help the body fight skin, colorectal, breast, lung, and prostrate cancers. (2) , (3) , (4) , (5)

Research indicates that CLA may help prevent and treat diabetes. This benefit may be the result of its potential ability to help stabilize blood sugar levels. (6)

Other studies have looked at CLA’s potential for lowering cholesterol levels. Animal studies suggest that CLA may reduce harmful cholesterol levels while leaving levels of HDL—the so-called “good" cholesterol— intact. CLA’s role in lowering cholesterol may further lead to a reduction in the risk of atherosclerosis. (7)

CLA may also play a role in the reduction of body fat; a function that researchers believe might help treat obesity. (8) , (9) CLA’s fat-fighting potential is thought to be linked to three factors. First, it may inhibit the body’s absorption of fat. It may also increase metabolism and alter the body’s use of energy during sleep. (10)

Finally, CLA may help reduce factors that contribute to the development of food-induced allergies. (11)

Toxicities & Precautions

Introduction

[span class=alert]Be sure to tell your pharmacist, doctor, or other health care providers about any dietary supplements you are taking. There may be a potential for interactions or side effects.[/span]

General

Although further research is necessary, experts have stated that CLA can be considered generally safe. However, two studies with humans have indicated that CLA caused increased levels of lipid peroxidation which is a risk factor for cardiovascular disease. (12) , (13) In addition, one study found CLA adversely affects glucose and insulin levels in those with Type 2 Diabetes. (14)

Pregnancy / Breast Feeding

To date, the medical literature has not reported any adverse effects related to fetal development during pregnancy or to infants who are breast-fed. Yet little is known about the use of this dietary supplement while pregnant or breast-feeding. Therefore, it is recommended that you inform your healthcare practitioner of any dietary supplements you are using while pregnant or breast-feeding.

Age Limitations

To date, the medical literature has not reported any adverse effects specifically related to the use of this dietary supplement in children. Since young children may have undiagnosed allergies or medical conditions, this dietary supplement should not be used in children under 10 years of age unless recommended by a physician.

References

  1. View Abstract: Pariza MW, Ha YL. Conjugated dienoic derivatives of linoleic acid: a new class of anticarcinogen. Med Oncol Tumor Pharmacother. 1990;7(2-3):169-171.
  2. View Abstract: MacDonald HB. Conjugated linoleic acid and disease prevention: a review of current knowledge. J Am Coll Nutr. Apr2000;19(2 Suppl):111S-118S.
  3. View Abstract: Hubbard NE, et al. Reduction of murine mammary tumor metastasis by conjugated linoleic acid. Cancer Lett. Mar 2000;150(1):93-100.
  4. View Abstract: Cesano A, et al. Opposite effects of linoleic acid and conjugated linoleic acid on human prostatic cancer in SCID mice. Anticancer Res. May1998;18(3A):1429-34.
  5. View Abstract: Parodi PW. Cows' milk fat components as potential anticarcinogenic agents. J Nutr. Jun1997;127(6):1055-60.
  6. View Abstract: Houseknecht KL, Vanden Heuvel JP, Moya-Camarena SY, Portocarrero CP. Dietary conjugated linoleic acid normalizes impaired glucose tolerance in the Zucker diabetic fatty fa/fa rat. Biochem Biophys Res Commun. Jun1998;247(3):911.
  7. View Abstract: Nicolosi RJ, et al. Dietary conjugated linoleic acid reduces plasma lipoproteins and early aortic atherosclerosis in hypercholesterolemic hamsters. Artery. 1997;22(5):266-77.
  8. View Abstract: Riserus U, Berglund L, Vessby B. Conjugated linoleic acid (CLA) reduced abdominal adipose tissue in obese middle-aged men with signs of the metabolic syndrome: a randomised controlled trial. Int J Obes Relat Metab Disord. Aug2001;25(8):1129-35.
  9. View Abstract: Gaullier JM, Halse J, Hoye K, et al. Conjugated linoleic acid supplementation for 1 y reduces body fat mass in healthy overweight humans. Am J Clin Nutr. Jun2004;79(6):1118-25.
  10. View Abstract: West DB, et al. Effects of conjugated linoleic acid on body fat and energy metabolism in the mouse. Am J Physiol. Sep1998;275(3 Pt 2):R667-72.
  11. View Abstract: Sugano M, et al. Conjugated linoleic acid modulates tissue levels of chemical mediators and immunoglobulins in rats. Lipids. May1998;33(5):521-7.
  12. View Abstract: Basu S, et al. Conjugated linoleic acid induces lipid peroxidation in humans. FEBS Lett. Feb 2000;468(1):33-6.
  13. View Abstract: Riserus U, Vessby B, Arnlov J, Basu S. Effects of cis-9,trans-11 conjugated linoleic acid supplementation on insulin sensitivity, lipid peroxidation, and proinflammatory markers in obese men. Am J Clin Nutr. Aug2004;80(2):279-83.
  14. View Abstract: Moloney F, et al. Conjugated linoleic acid supplementation, insulin sensitivity, and lipoprotein metabolism in patients with type 2 diabetes mellitus. Am J Clin Nutr. 2004 Oct;80(4):887-95.