A low protein diet when used with chemotherapy, restricts tumour growth, chemo-resistance, and delivers a demand versus supply crisis in cancer cells, resulting in less tumour growth, less chemo-resistance and more cancer cell death from drugs.
In a study using both colorectal cancer cell lines and mice with the disease, researchers from the University of Michigan have shown that restricting amino acids (and thus protein) allows chemotherapy drugs to work better.
The mammalian target of rapamycin (mTOR) often runs out of control in human cancers. This deregulation seems particularly linked with protein (1) and why some nutritionists advise people with cancer to avoid red meat This led to the prediction that mTOR inhibitors may be useful in oncology (2) and there are animal studies showing that mTOR inhibitors inhibit tumour growth. The problem is that as soon as you cease the inhibitors, the tumours grow again.
Studies have also shown that mTORC1 molecules sense certain nutrients and are hyperactivated in tumour growth in many cancers. In this study, researchers started by taking human cancer cells and showed that restricting proteins (as amino acids) enhanced drug performance (3).
Next the researchers fed mice with colorectal tumours a diet containing just 4 per cent protein (the usual diet is 21 per cent) and after two weeks they added the chemotherapy drugs for a month. They found that the low protein mice had less tumours, slower growth and a heightened chemotherapy performance.
Studies have shown that the amino acids may not have a direct effect on mTOR. When amino acids are abundant, another pathway GATOR2 activates mTORC1. However, when amino acids are low, GATOR1 deactivates mTORC1.
They further found that the amino acids leucine and cysteine had a strong effect on drivers GATOR1 and GATOR 2, which in turn activate mTORC1
The Michigan researchers found that amino acids leucine and cysteine had a strong effect on GATOR1.
Dr Summit Solanki, lead investigator, drew several conclusions; for example, that tests for which amino acids were drivers in different cancers might be helpful; that chemo-resistance might be prompted more by certain amino acids than others; and that feeding a low protein diet to animals created a demand versus supply crisis in colon cancer cells which resulted in massive cancer cell death,
Former Oxford University Biochemist and a CANCERactive founder Chris Woollams said, "These findings are directly in line with why we use fasting when having IV Chemo - there is far less chemo-resistance and weaker cancer cells respond more to the cancer drugs. And it's why we always encourage a Rainbow diet with mainly fish and some lean organic skinless chicken as the only non-vegetable proteins.
But there's an important twist it is easy to ignore - leucine is an essential amino acid in muscles, metabolism and tissue repair - Beef, milk, eggs and cheese are high in leucine, but even salmon, beans, tuna and seeds are good sources; for cysteine, it is an essential ingredient in cancer-fighting, anti-aging glutathione - Beef, pork, cheese and milk are top sources, but so too are oatmeal, lentils, seeds and tuna.
As I have said before - for example with the Keto Diet - you can't just cut out meats from your diet and assume you've cut your protein or amino acids!"
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