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Weight-loss supplements containing raspberry ketone may be harmful

Wednesday 20 Jan 16


Lea Bredsdorff
Senior adviser
DTU National Food Institute
+45 35 88 75 22


Kirsten Pilegaard
Senior adviser
DTU National Food Institute
+45 35 88 75 65
If your trousers are feeling a little too tight post-Christmas and a weight-loss supplement seems tempting in an attempt to shed the extra weight, researchers from the National Food Institute, Technical University of Denmark, are urging care when it comes to buying products online that contain raspberry ketone. Few studies have assessed the safety of raspberry ketone. However, a new study by the researchers suggests that the substance may have several adverse effects.

The substance 4-(4-hydroxyphenyl)-2-butanone, which is popularly known as raspberry ketone, gives raspberries most of their flavour. The substance has been approved for use as a flavouring substance in foods in very small quantities.

The raspberry ketone content in the fresh fruit is very small: One kilo of fresh raspberries contains 0.009-4.3 mg raspberry ketone. Therefore food manufacturers mainly use raspberry ketone which has been chemically produced with the help of microorganisms.

Little knowledge about the intake of large doses

An adult’s average daily intake of raspberry ketone through the diet is between 1.8 and 3.8 mg and most of it comes from its use as a flavouring agent. However, the substance is also found in certain weight-loss supplements, which can be purchased online. Producers of these products recommend a daily dose of between 100 and 1400 mg.

While the substance has been approved as a flavouring substance, no Danish or international authorities have approved the safety of using large doses of the substance as a weight-loss supplement.

According to a team of researchers from the National Food Institute the problem is that the safety of such large daily intakes has never been assessed. Weight loss has been observed in laboratory animals in a few studies, but the reason behind this weight loss is unknown. Toxicologists generally see a weight loss in laboratory animals as an indicator of an adverse effect if the mechanism behind the weight loss is not known.

Using computers to map out adverse effects

In order to better understand the possible effects of the substance the researchers have made use of QSAR (Quantitative Structure-Activity Relationship). With the help of advanced computer models it is possible to predict what adverse effects a substance may have based on whether the chemical structure of the substance is similar to substances that have already been tested.

QSAR has indicated that the substance may have potential adverse effects on both the reproductive and cardiovascular systems as well as on fetal development. Therefore the substance should be further examined in order to determine whether it is safe to use in the high doses found in weight-loss supplements. As such consumers should exercise caution when using products containing raspberry ketone.

According to researcher Lea Bredsdorff the assessment of raspberry ketone is a good example of how the QSAR tool can be used in situations where little safety data is available in order to get an idea about the potential adverse effects of a substance.

The name is crucial

In the online marketing of weight-loss products containing raspberry ketone they are described as 100% natural, which gives the impression that the substance has been extracted from the fruit. However, the safety of the substance is not dependent on whether it has been extracted from the fruit or it has been industrially manufactured.

It is not legal for weight-loss supplements containing raspberry ketone to be sold in Danish stores.

Read more

The problem of the high intake of raspberry ketone and the lack of toxicological data is described in a scientific article in the journal Regulatory Toxicology and Pharmacology: Raspberry ketone in food supplements – High intake, few toxicity data – A cause for concern?

The QSAR database is one of the largest freely-available QSAR tools in the world for use by industry, government and researchers. The tool is described in further detail on QSAR’s website.