The Side Effects of CLA Supplements

CLA, or conjugated linoleic acid, is a nutritional supplement used by body builders to help build muscle and promote fat loss. It’s sometimes marketed under the brand name of Tonalin CLA as a weight loss supplement and as a supplement for building lean body mass. It’s also used being increasingly used by ordinary people as a weight loss supplement. Although this supplement has grown in popularity, little attention has been focused on the potential risks. What are the side effects of CLA supplementation?

What is CLA?

Conjugated linoleic acid is a fatty acid found primarily in meat and dairy products. CLA initially gained attention in the 1970’s when studies showed that it reduced cancerous tumor growth in animals at a variety of sites including the skin and colon. Further research also revealed another use for CLA. Studies suggested that supplementing with CLA helped to reduce body fat, particularly abdominal body fat. It appeared to do so by inhibiting an enzyme involved in fat storage known as lipoprotein lipase. Several other studies in humans showed that it might help weight lifters and athletes build more muscle mass without altering their diet.

Does It Work?

It’s still not clear whether CLA supplements actually do what they’re advertised to do. Several studies where obese individuals took CLA supplements showed they lost more weigh than controls, particularly in the abdominal region. Other studies have shown no benefits of CLA supplements. Most recently a meta-analysis (a study looking at a large group of studies) showed that a CLA dose of 3.2 g/d was associated with modest weight loss and loss of body fat in humans.

What About the Side Effects of CLA?

Unfortunately, there’s been little focus on the side effects of CLA. Some forms of CLA appear to raise insulin levels and blood glucose which would be of concern for those with diabetes or metabolic syndrome. Another area of concern is its effect on heart health. One form of CLA appears to increase c-reactive protein, a protein that serves as a marker for inflammation and heart disease. This raises the question as to whether it’s safe for people at higher risk of heart disease.

Are There Other Side Effects of CLA?

The safety of CLA hasn’t been established for women who are pregnant or breast feeding and should be avoided. Other risks of CLA include the potential for allergic reactions and digestive upset.

The Side Effects of CLA: The Bottom Line?

There doesn’t seem to be enough evidence to support use of CLA as a weight loss supplement since human studies have been conflicting. There are also concerns about its effect on blood sugar and c-reactive protein levels. This is a supplement that’s probably best avoided until more conclusive evidence comes out.