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• Cancer cells need certain nutrients to live, so tumors hijack vitamins, minerals, and amino acids, including methionine, from your diet to feed themselves.
• Tumors depend on methionine, found mainly in animal meats, to grow.
• Cancerous cells have a higher requirement of methionine than healthy cells do. You can limit the methionine that cancerous cells have available by limiting your animal protein.
• Keep reading to find out how methionine and tumors work together.

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Cancer cells need certain nutrients to live, so tumors hijack vitamins, minerals, and amino acids, including methionine, from your diet to feed themselves. You can use this information to your advantage. Keep reading to find out how methionine and tumors work together, and how to eat so that you don’t give cells with damaged DNA too much methionine.

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What is methionine?

Methionine is an essential amino acid (a building block of protein), which means your body doesn’t make it, and you have to get it in foods. It’s found in meats and animal products, and lesser amounts in plant sources of protein. Methionine has four major roles in your body:

• Combines with other amino acids to make proteins for your body
• Precursor to glutathione, your body’s “master antioxidant”[ref url=”https://www.ncbi.nlm.nih.gov/pubmed/9679538″]
• Helps form compounds that ensure healthy cell division[ref url=”https://www.ncbi.nlm.nih.gov/pubmed/11289306″]
• Helps with DNA replication — faulty DNA replication can lead to tumors

Methionine dependency and tumors

Tumors depend on methionine to grow. Researchers discovered in the 1970s that tumors will not grow in its absence. Scientists call this phenomenon “methionine dependency.”[ref url=”https://www.ncbi.nlm.nih.gov/pubmed/2213904 https://www.ncbi.nlm.nih.gov/pubmed/8495409″]

Cancerous cells have a higher requirement of methionine than healthy cells do. Radiologists use this notion to their advantage. They inject patients with radioactive methionine to measure the size and location of brain tumors, and because brain tumor cells gobble it up, tumors will light up on a scan much brighter than surrounding cells.[ref url=”https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4827046/”]

What makes this promising for cancer treatment is that normal, healthy cells aren’t methionine dependent — only tumor cells need methionine to survive.[ref url=”https://www.sciencedirect.com/science/article/pii/S030573720300118X”] When there isn’t enough methionine, healthy cells get what they need from another amino acid called homocysteine. Cancer cells, especially the ones that are highly dependent on methionine to grow, cannot use homocysteine to meet their methionine requirements and will die off when there’s not enough.[ref url=”https://www.sciencedirect.com/science/article/pii/S030573720300118X”][ref url=”http://cancerres.aacrjournals.org/content/49/17/4859.short”]

Scientists have been able to shrink tumors using both diets that limit methionine or using an enzyme that breaks down methionine, rendering it useless in the body.[ref url=”https://www.sciencedirect.com/science/article/pii/S030573720300118X”]

Can avoiding methionine cut your risk of cancer?

Certain tumor cell types are hungrier for methionine than others,[ref url=”https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4827046/”] but they all need methionine to survive and grow.

So, do you eliminate it? Since methionine helps with protein synthesis, production of glutathione, supports bones, and it helps your genes express properly, among other important functions, it’s not a good idea to avoid it entirely. The key is to adopt a low-methionine diet.

Research shows that low methionine diets can increase the lifespan of animals.[ref url=”https://www.ncbi.nlm.nih.gov/pubmed/18789600″] One reason is that low methionine diets slow cancer growth[ref url=”https://www.ncbi.nlm.nih.gov/pubmed/22342103″][ref url=”https://www.ncbi.nlm.nih.gov/pubmed/22342103″] Another reason is that it increases levels of glutathione in the bloodstream,[ref url=”https://www.ncbi.nlm.nih.gov/pubmed/8001743″] which is protective against damaging oxidative stress and therefore prevents disease processes from starting. Methionine also decreased the rates of several aging measures, like hormone levels and cataracts, in rats,[ref url=”https://www.ncbi.nlm.nih.gov/pubmed/12543260″][ref url=”https://www.ncbi.nlm.nih.gov/pubmed/15924568″] which shows promise for slowing aging in humans.

How to eat a low methionine diet

Whether you have cancer or not, you’ll benefit from lowering your methionine levels for general longevity purposes and to keep oxidative stress low.

Foods containing high levels of methionine include:[ref url=”https://ndb.nal.usda.gov/ndb/”]

• Eggs
• Fish
• Game meats
• Dairy products
• Poultry, especially turkey
• Grass-fed meats

There are also plant sources of methionine. People on a vegan diet typically consume low methionine and will generally miss out on vital nutrients like collagen protein and vitamin B12, among others that you only find in animal products.

The standard American diet, traditional keto diets, paleo diets, and others focus on meat or animal products as the main event on your plate. That’s too much methionine. The Bulletproof Diet is moderate in protein by design, for reasons like this — excessive amounts of certain amino acids can cause problems.

To reduce your methionine, it’s easy to eyeball your meat portions. Cover your plate with vegetables, add just a few ounces (like the size of 2-3 of your fingers) of grass-fed meat or wild-caught fish, then add plenty of healthy fats. That’s it. No need to measure.

Bonus: do a protein fast

One to two days a week, do a protein fast. All you need to do here is consume no more than 15g of protein in a day, and add a little extra fat to feel full. Brain Octane oil is a flavorless, versatile way to do this — you can put it on almost anything. You’ll likely get to your protein upper limit with veggies alone.

Protein fasting kickstarts autophagy, the process by which your cells clean house. Cells that are free from damaged DNA pieces and faulty organelles work more efficiently and are more resistant to the damage that results in tumor formation. That, on top of starving any cancerous cells of methionine, results in a multi-angle approach to keeping your cells, and your cell division, healthy.