Palm oil is the most widely used vegetable oil on the planet, used as a raw material in both food and non-food industries. Around 50% of all supermarket products, from cosmetics to ice cream, contain the ingredient.
While relatively high in saturated fats – around twice the amount as olive oil – palm oil also contains monounsaturated and polyunsaturated fats, which can help maintain healthy cholesterol levels.
However, a potential health concern has been raised by researchers in Spain: that of a fatty acid found in palm oil being associated with cancer spread in mice.
Palm oil thought to favour cancer development
Dietary palmitic acid is a solid saturated acid found in the commonly used oil. In a new study out of IRB Barcelona and Northwestern University in Illinois, patients with oral tumour cells and melanomas consumed a diet rich in palmitic acid.
When the cancer cells were transplanted into mice, the researchers observed a spread into other parts of the body.
So what are the implications for palm oil? “Our results indicate that a diet rich in palm oil would favour the development of cancer, even if exposure to this fatty acid occurs in a very early stage of the disease in which the primary tumour may still not have been detected,” noted the researchers.
They were able to rule out similar associations with acids found in olive or flaxseed oil, notably oleic acid and linoleic acid.
“These results suggest that aggressiveness is linked not only to fat metabolism but also to epigenetic modifications that occur in tumour cells in response to exposure to palmitic acid.”
‘This is early-stage research’
In response to the research, the European Food Information Council (EUFIC) stressed some limitations.
Firstly, that the study was not carried out on humans, but on mice: “Even if animal studies are helpful to understand biological processes that may apply to humans, they still have limitations.”
“For example, the conditions of this experience may not be representative of the typical amounts of palm oil consumed in the human diet.”
Secondly, the metastatic effect of palmitic acid was only shown with two specific types of cancer cells. In involving only mouth (oral squamous cell carcinoma) and skin (melanoma) cancer cells, the findings cannot be generalised for other types of cancer, we were told.
EUFIC also flagged the research, which it described as a ‘good quality study’, as ‘early-stage’, suggesting more studies are needed to be certain of the impact of palm oil consumption on the spread of cancer in humans. The non-profit also said more research is required to determine whether findings could pave the way to new treatments to prevent or slow cancer spread.
The research team remains hopeful their findings could influence developments in metastasis-blocking therapies.
Ninety percent of cancer deaths are caused by the spread of cancer cells.
Several ‘memory’ markers left in tumour cells after exposure to palmitic acid were identified by the scientists, which they described as a change that causes cells to conserve greater metastatic capacity. This ‘memory’ marker can be found months after exposure to the fatty acid, meaning it could be linked with a greater capacity of these tumour cells to promote innervation.
The neural network that forms around the tumour produces a regenerative environment, which the cells use to their advantage to grow and spread. However, if one of the key elements in the formation of the neural network, the so-called Schwann cells, can be inhibited, the thinking is that metastasis could be reduced or prevented.
“In 2017, we published a study indicating that palmitic acid correlates with increased risk of metastasis, but we didn’t know the mechanism responsible for this,” recalled co-first author and ICREA researcher at IRB Barcelona Dr Salvador Azar-Benitah.
“In this study, we detail the process and reveal the involvement of a metastatic capacity ‘memory’ factor and we point to a therapeutic approach to reverse it. This is promising.”
Co-author Dr Gloria Pascual, association researcher in the Stem Cells and Cancer lab at IRB Barcelona, added: “This discovery paves the way for research into and the development of therapies that specifically block cancer metastasis, a process that is almost always the cause of death by cancer.”
‘Dietary palmitic acid promotes a prometastatic memory via Schwann cells’
Published online 10 November 2021
Authors: Pascual, G., Domínguez, D., Elosúa-Bayes, M. et al.