Can eating peanuts spread cancer?

5 September 2021

Eating peanuts raises peanut agglutinin in the bloodstream and this may mimic the action of Galectin-3 promoting cytokine formation and the increased adhesion of cancer cells to the vascular epithelium, a known step in cancer metastasis and lowered cancer survival.

In a 2011 study from Liverpool University, serum galectin-2, -3, -4, and -8 are greatly increased in colon and breast cancer patients and promoted cancer cell adhesion to the blood vascular endothelium (1). Why is this important? Well, tumour cells sticking to the blood vascular system walls is a pivotal step in metastasis. In fact, the study showed that levels of serum galectin were a staggering 31-times higher in patients with cancer and, in particular, those with metastases. And in 2010 the same team showed (2) that free circulating galectin-3 increased the survival of cancer cells in the blood, their ‘clumping’ together, and Gal-3 promoted vascular wall binding following an interaction with mucin cancer-associated MUC1, which modifies the cancer cell surface.

A study in 2015 (3) confirmed that galectin-3 promoted metastasis by cancer cell adhesion to the vascular wall.

Galectins and especially galectin-3 have been found to play important roles in spreading all manner of cancers from prostate to pancreatic, and studies to limit them using glycoproteins and N-acetyl lactosamines analogues have restricted metastasis, for example in a 2016 study (4) on renal cancer, where Gal-3 ‘knockdown’ promoted p27 and restricted tumour activity.

So, that’s the science.

In 2014, the Liverpool team of researchers found (4) that when peanuts were ingested, peanut agglutinin appearance in the blood mimicked the action of natural galectin-3 to promote metastasis by interaction with cancer-associated MUC1. Peanut agglutinin (PNA) is just 0.15% of a peanut by weight, but it is resistant to cooking and digestion, rapidly enters the blood circulation, and uses MUC1 to mimic the action of galectin-3 to promote metastasis. The researchers warned that eating peanuts once you had cancer ‘would therefore be expected to have an adverse effect on cancer survival.’

But one swallow doesn’t make a cancer spread, I hear you say.

In a study (6) by Wang et al and posted in Carcinogenesis in 2020, peanut agglutinin was shown to interact with endothelial cells - the single cell lining in all blood vessels - to produce cytokines IL-6 and MCP1, both known promoters of metastasis. The mechanism shown was that the increased cytokine production caused the endothelial cells to produce more cell surface adhesion molecules, promoting metastasis.

Go to: Is Coffee good or bad for cancer?

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