A typical adult’s body contains 60,000 miles’ worth of blood vessels, enough to circle the Earth twice around. The smallest of these blood vessels are called capillaries, of which we each contain around 19 billion. In a way, these are the vessels that carry life, but can also carry death. 

The body is able to regulate the number of blood vessels that are present at any given time through an elaborate system of stimulants and inhibitors. This process, known as angiogenesis, controls the formation of new blood vessels. When we need an increase in blood vessels, such as after an injury or during pregnancy, existing blood vessels release stimulators (proteins called angiogenic factors) that prompt the growth of new blood vessels. When these excess blood vessels are no longer needed, the body prunes them back to a baseline amount using the naturally occurring inhibitors in angiogenesis. 

However, for a number of diseases, there are evident defects in this system, in which the body either can’t prune back extra blood vessels or can’t grow enough new ones when they are needed. 

As explained by Dr. William Li in his TED Talk “Can we eat to starve cancer?,” this imbalance of angiogenesis results in a variety of severe diseases. Insufficient angiogenesis (not enough blood vessels) leads to conditions such as chronic wounds, coronary heart disease and neuropathy. Excess angiogenesis (too many blood vessels) also drives disease, as seen with cancer, arthritis and obesity.

“In total, there are more than 70 major diseases affecting more than a billion people worldwide that share abnormal angiogenesis as their common denominator,” Li said. 

Abnormal angiogenesis is present in every cancer, although cancers are completely harmless when they first begin growing. Cancers start out as microscopic nests of cells that only grow to 0.5 cubic millimeters in size (approximately the tip of a ballpoint pen). These nests can’t get any larger because they don’t have a blood supply and are therefore unable to access enough oxygen and nutrients. 

According to Li, “autopsy studies from people who died in car accidents have shown that about 40% of women between the ages of 40 and 50 actually have microscopic cancers in their breasts. About 50% of men in their 50s and 60s have microscopic prostate cancers. Virtually all of us by the time we reach our 70s will have microscopic cancers growing in our thyroid.”

We are probably forming these microscopic cancers all the time in our bodies, but most of them will never become dangerous. With a normal balance of angiogenesis, your body can prevent blood vessels from ever reaching cancer cells, thereby preventing tumors from growing. 

The issue occurs when cancer cells mutate and gain the ability to produce lots of angiogenic factors that prompt blood vessels to grow toward the cancer source. Once the tumor has access to oxygen and nutrients from the blood vessel, it can expand and invade local tissues. These blood vessels not only feed tumors but enable cancer cells to enter our circulation and metastasize. Once angiogenesis occurs, cancers grow exponentially and go from being harmless to potentially deadly. This late stage of cancer is the one at which people are most likely to be diagnosed. 

Unlike with chemotherapy, recently discovered anti-angiogenic therapy cuts off the blood supply to tumors by targeting the blood vessels that feed cancers. The first pioneered treatments for people as well as dogs are already becoming available. There are 12 different drugs encompassing 11 different cancer types, such as Avastin which treats colon, lung, breast, brain and kidney cancer, as well as Palladia which treats mast cell tumors in canines. 

“Starting in 2004, when anti-angiogenic therapies first became available, there has been a 70-100% increase improvement in survival of cancer patients with metastatic kidney cancer, multiple myeloma cancer, metastatic colorectal cancer and gastrointestinal stromal tumors compared to when chemotherapy and radiation were the only available treatments,” Li said. But rather than treating cancer when tumors have already metastasized, he is focusing on helping individuals avoid cancer altogether through the prevention of angiogenesis. 

With the discovery that diet accounts for 30-50% of environmentally caused cancers, Li used a testing system of food extracts and blood vessels to create a list of naturally anti-angiogenic foods that boost the body’s defense system and beat back cancer-feeding blood vessels. Included in this list are green tea, berries, citrus, red grapes, red wine, bok choy, kale, soy beans, ginseng, maitake mushrooms, licorice, turmeric, nutmeg, artichokes, lavender, pumpkin, sea cucumber, tuna, parsley, garlic, olive oil, grape seed oil, dark chocolate and many more common foods.

Lorelei Mucci, an epidemiology professor at the Harvard T.H. Chan School of Public Health, stated that, based on a Harvard study of 79,000 men, “men who consume 2-3 servings of cooked tomatoes per week have a reduced risk for developing prostate cancer by 40-50%.” Among the 8,200 men who did develop prostate cancer, those who ate more servings of tomato sauce had fewer blood vessels feeding their cancer. This study is just one example of how anti-angiogenic substances consumed at practical levels can have a huge impact on cancer development. 

As stated by Li, “for many people in the world, dietary cancer prevention may be the only practical solution because not everybody can afford expensive in-stage cancer treatments. But everybody could benefit from a healthy diet based on local, sustainable anti-angiogenic crops.”