By Datuk Dr Kalyana Sundram
NATURE, a high impact, prestigious peer reviewed science journal, published a landmark study last week (10 November 2021) that could help trigger advanced developments in cancer management. The joint publication was from Spanish and US biomedical researchers, in a mice animal model. For the understanding of our lay readers, the study described how cancer metastasis (i.e. when cancer cells break away from the main tumour and start spreading to other organs and sites) is facilitated by consumption of certain dietary fatty acids, particularly palmitic acid, that is part of our daily diets.
Media hounds were quick to pick this up, particularly since they saw the fall guy from the study, a low hanging fruit, ripe and ready for a thorough public bashing. Palm oil was used as a primary source of palmitic acid and by extrapolation and simplification of the study, headlines screamed that palm oil with its higher palmitic acid content was a cancer promoter.
They then even moved to offer veiled opinions about palm oil’s lack of safety and efficacy as a dietary ingredient in the human food chain. Called to question was also the occurrence of glycidol esters in palm oil reported previously by various media.
I suggest a step back to assimilate the facts at hand. As scientists we have long realised that fat and fatty acid uptake from any source and their sometimes accompanying altered metabolism can be hallmarks of cancer metastasis. Yet the depth of understanding, even today, is still so shallow that a health call on fats and fatty acids associating them with cancer has so far not been warranted.
Nevertheless, it has long been known that high fat diets can promote cancer and hence the nutritional advice for moderate fat consumption always. The current study is exciting since it helps narrow the underlying molecular and genetic markers and mechanisms that are triggered by fatty acids and which possibly make some, if not all of these fatty acids, essential components or even triggers for the progression of certain types of cancer.
Palm oil non-cancer promoting
Let us also be clear that dietary fats and fatty acids, even in this study, were themselves not the initiators of cancer. Nutritional history, traced through decades of scientific publications, will bear evidence to this fact. For example in the 1980s, when interest was very high on diet and cancer, research on dietary fats was a hot topic.
Several authoritative publications narrowed cancer progression in rat models to the polyunsaturated fatty acid, linoleic acid, found in common seed oils such as corn, soya, sunflower and rapeseed. The evidence against linoleic acid in rats, induced cancer by administration of chemical carcinogens, was actually overwhelming. These studies yielded evidence that dietary sources of linoleic acid need to be managed in order to manage progression of certain types of cancer. This was despite its role as an essential fatty acid in humans and its requirement for a variety of other critically important metabolic functions.
Curiously at this stage, as a young researcher, I got into this fray and tested various palm oil fractions for their carcinogenic effects. The key was the fact that palm oil was low in its linoleic acid content and, when tested in such a rat cancer model, palm oil proved to be non-cancer promoting. Actually, significantly less carcinogenic than the comparative corn and soya oils tested.
The study was published in Cancer Research, 1989 (Sundram K. et al.). Researchers also found that the vitamin E tocotrienols and carotenes in palm oil displayed anti-cancer properties in a wide variety of cell cultures and animal model studies. These findings triggered a debate to call palm oil as anti-cancer but I personally opposed this label and rightly so. For me and other similar learned researchers, there was really no such thing as a pro-cancer or anticancer fat. Even to this date, this point of view prevails and holds true.
Often we are advised that we are what we eat. Diet and various dietary components have a long and coloured history and fit with our preponderance to manage cancer incidence and mortality. Another dietary fat type that has been in the spotlight for its association with cancer is animal fat. Again studies can be tracked associating animal fat consumption with colorectal cancer incidence and mortality. In this case, animal studies were followed through with human epidemiological observations. The association seemed strong yet no ban on animal fats as part of human nutritional needs is apparent.
There is also relatively strong evidence that eating red and processed meat causes certain types of cancer, particularly colorectal cancer. This association appears even stronger for processed meat which has been preserved by smoking, curing, salting or via chemical preservatives such as nitrates and nitrites. This essentially means you need to avoid ham, bacon, frankfurters, sausages and even burgers. But once again we have not seen universal health exclusion of these products.
Bottom line is that if you are fetish about food and cancer, you are not going to run too far from the current practices of the global processed food chain. As science unravels the mystery behind each food component we consume, be prepared for additional shock waves. For even the simple practice of toasting a slice of bread and charring its surface has enough evidence to suggest you are swallowing a pro-cancer trigger.
Circling back to the current controversy about palm oil and palmitic acid, let us not forget that palmitic acid is present in all oils and fats and foods that have a lipid component. It is the most abundant saturated fatty acid in nature and is similarly reflected throughout the human body.
In your body fat deposits or adipose fat, it is nearly 21-25% palmitic acid. Even the most claimed healthy oil or fat will have its share of palmitic acid.
So when the media swings into its frenzy focusing on palm oil and forgetting all other sources of the same fatty acid, readers are being served only half-baked information. In reality, palmitic acid has an important role in human development and metabolism. At birth, the young infant is nourished with breast milk that is rich in this fatty acid. It further plays an active and desired role in various metabolic functions in humans that are fundamental to the very existence of life as we know it.
But the current findings potentially show what could happen in an environment that is oversupplied by any of these regular fatty acids including palmitic acid. In the mice study, prometastastic outcomes were observed with all the fats and fatty acids tested but palmitic was more potent in impacting several key molecular and genetic pathways crucial for metastasis to proceed. The researchers also clearly identified that this fatty acid along with all other fatty acids were not responsible for initiation of cancer.
So what dietary counselling can be offered to those facing cancer. Without doubt, controlled dietary regimes help and it has long been known that caloric restriction is advocated. This will mean overall fat reduction and possibly even keeping an eye on the quality of fat consumed.
Will this mean reduction in your exposure to palmitic acid? The mice study appears to point in that direction, but will this be successfully reproduced in humans?
We need to watch for the next phase of these studies. Often observations in animals and especially those from cell culture studies have been hard to have meaningful replications in humans. So for me it was noteworthy learning that the investigators have been offered private funding of almost Euros 30 million to carry out the next phase of clinical trials to replicate the observations from the current mouse model.
Until then, any advocacy to throw out any fat is not yet warranted. I am sure that various nutritional experts will seize the opportunity and we could see the evolution of tailor-made dietary regimes that propose modified dietary recommendations to slow the prometastastic effects of fats and fatty acids. These will however remain unproven until science deciphers the underlying secrets and we hope that these will thereafter create crucial solutions for cancer prevention and management.
Meanwhile, a lesson that the palm oil industry needs to learn. Palm oil is highly targeted and vulnerable. For some time now the industry’s kingpins have sat on their laurels and have not been investing into rigorous science that could help negate the concerns of the consumers.
Our palm oil industry stakeholders, enriched by the commodity, need to come clean and fork out part of their lucrative profits for sustained research even if these have no possibility of monetary returns. For example, I did not see any one from the industry jumping in to fund research that could help unearth relevance of these current findings, even if they looked negative for palm on the surface.
Hopefully we can look forward towards better and more meaningful outcomes especially when palm oil is here to stay as part of the mainstream food supply chain for the global masses.
Datuk Dr Kalyana Sundram, a former CEO of the Malaysian Palm Oil Council (MPOC), is now retired and has 40 years of experience over a large spectrum of oils and fats and particularly in palm oil related research and professional activities.
He has served on international expert consultations and committees, publishes extensively, and holds 21 patents, and has coordinated more than 170 research and consumer promotion projects, primarily on nutrition and health, food technology and more recently sustainability and wildlife conservation.