07 June 2005

A - Z of CLA

Research relating to conjugated linoleic acid (CLA) is still in its early stages. DietDoc takes a look at some of the results that have been obtained so far.

Research relating to conjugated linoleic acid (CLA) is still in its early stages. However, it may be worth your while to take a look at some of the results that have been obtained so far.

What is CLA?
CLA is the abbreviation for conjugated linoleic acid (CLA), an essential fatty acid.

How does it work?
Animal studies have found the following in relation to CLA:

  • CLA decreased fat tissue and lowered leptin (a hormone implicated in obesity) levels in mice.
  • There is some indication from animal studies that CLA may also help to control insulin resistance (a condition that is associated with weight gain).

Yet, there is not enough evidence to let us conclude that CLA can assist with slimming.

Results obtained from animal studies cannot always be directly transferred to humans. If the animal studies have indicated that CLA has the above-mentioned effects, then we can start looking for similar effects in humans, and only when we have obtained plenty of proof can we say that CLA also works in humans.

A study conducted with 60 overweight subjects, who were either given CLA in varying quantities or olive oil (the placebo - a treatment that is not supposed to have any effect and can act as a control), found that the subjects receiving CLA had a significantly higher reduction in body fat mass than the subjects receiving placebo (Blankson and co-workers, 2000).

In a Swedish study, 25 men suffering from abdominal obesity (the type of obesity that is regarded as particularly harmful and is associated with the metabolic syndrome) were either given 4,2g of CLA a day, or placebo. The group receiving CLA had significant decreases in abdominal fat, but otherwise no differences were observed between the two groups (Riserus and co-authors, 2001).

Why you may consider using CLA
People who want to lose weight.

What it can do
Although studies with humans showed that CLA resulted in:

  • an increase in fat-free mass;
  • a reduction of appetite and improved feelings of satiety;
  • a long-term reduction in body weight

Not all researchers are convinced that CLA can induce weight loss.

Larsen and co-workers (2003) reviewed CLA studies in humans that lasted longer than four weeks. They concluded that CLA dietary supplements are not effective weight loss agents and that they may actually have adverse effects on human health (e.g. increased 'bad cholesterol' and total blood fat levels, reduced 'good cholesterol' and increased insulin resistance). Other experts who believe that commercial CLA supplements are safe, have challenged this conclusion.

What it cannot do
Many experts believe that it does not play any role in weight loss.

Harmful effects

Who may benefit
There is not sufficient evidence that anybody will benefit.

Who should not use it
People with elevated blood cholesterol and lipid levels. This may increase their risk of a heart attack.

Sufficient scientific evidence

At the moment all we can deduce is that the jury is still out on the effects of CLA on slimming. We need additional studies to produce the sort of evidence that is conclusive.

No. Legal.

You will probably waste your money. If you are considering the use of CLA supplements to help you lose weight, no one can be sure that they will work or not. The chances are that if you use CLA together with an energy-reduced diet and regular exercise, you will lose weight, but the latter two components would have produced the same effect anyway.

You need to decide if you want to spend extra money on a supplement that may, or may not, enhance weight loss. – (Dr Ingrid van Heerden, DietDoc)

(References: Blankson et al (2000). J Nutr, 130(12):2943-8; Larsen et al (2003). J Lipid Res, 44(12):2234-41; Riserus et al (2001), Int J Obes Relat Metab Disord, 25(8):1129-35)


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