Hippocrates said it first, “Let food be thy medicine”. People have been trying to heal disease with food for thousands of years. Several prominent doctors have claimed that food can even heal cancer. Today I am going to explore one of these claims.
Internal medicine doctor, William Li, gave a viral TED Talk in 2012 describing how he believes food can prevent and even help cure many kinds of cancer. A reader provided me with the link to the talk below and asked for my thoughts.
In order to understand his hypothesis, a little bit of background info on a process called angiogenesis is needed. Here is the description from the National Cancer Institute:
“What is angiogenesis?
Angiogenesis is the formation of new blood vessels. This process involves the migration, growth, and differentiation of endothelial cells, which line the inside wall of blood vessels.
The process of angiogenesis is controlled by chemical signals in the body. These signals can stimulate both the repair of damaged blood vessels and the formation of new blood vessels. Other chemical signals, called angiogenesis inhibitors, interfere with blood vessel formation. Normally, the stimulating and inhibiting effects of these chemical signals are balanced so that blood vessels form only when and where they are needed.
Why is angiogenesis important in cancer?
Angiogenesis plays a critical role in the growth and spread of cancer. A blood supply is necessary for tumors to grow beyond a few millimeters in size. Tumors can cause this blood supply to form by giving off chemical signals that stimulate angiogenesis. Tumors can also stimulate nearby normal cells to produce angiogenesis signaling molecules. The resulting new blood vessels “feed” growing tumors with oxygen and nutrients, allowing the cancer cells to invade nearby tissue, to move throughout the body, and to form new colonies of cancer cells, called metastases.
Because tumors cannot grow beyond a certain size or spread without a blood supply, scientists are trying to find ways to block tumor angiogenesis. They are studying natural and synthetic angiogenesis inhibitors, also called antiangiogenic agents, with the idea that these molecules will prevent or slow the growth of cancer.”
There are many FDA approved drugs that treat cancer by preventing or slowing angiogenesis. Dr. Li promotes these drugs. However, he also makes the claim that many foods work just as well or even better than these drugs at inhibiting angiogenesis.
Certain foods can inhibit angiogenesis just as well as or better than drugs to treat cancer patients.
After spending several hours googling things like “cancer diet” and “angiogenesis food”, I kept coming up with results leading me back to Dr. Li’s TED Talk. I also came across several websites and foundations represented by Dr. Li including: Eat to Beat, The Angiogenesis Foundation, Alternative Daily, Forks Over Knives, Food Revolution, Collective Evolution, and everyone’s favorite doctor, Dr. Oz.
Interestingly, not one mainstream reputable source mentioned his hypothesis and I was unable to find other doctors in his line of work. Could it be a conspiracy? Big Pharma? Or…….MONSANTO??? Kidding. But really, he seems to be the only one out there peddling this stuff.
Some of his associations provide links to articles by other professionals. However, you have to register to get access to them and many of the authors don’t have doctorates or even any credentials at all.
Several more reputable sources including: MD Anderson, the American Institute of Cancer Research, the World Cancer Research Fund, and WebMD do list foods that can help lower your risk of cancer. However, they do not discuss angiogenesis. I can’t tell whether it’s because the topic is too scientific or because they help prevent cancer through another mechanism or because they just don’t know how the foods help. None of these sources claim that foods can cure cancer or that foods work as well as or better than drugs for prevention and/or treatment. It’s worth noting that many of the foods are similar to those Dr. Li recommends. All of the food lists are heavy on fruits, veggies, legumes and spices. Some include coffees, teas, nuts and even yogurt and sea foods.
What is the quality of the research to support this claim? Are we going to find a bunch of retrospective observational studies that rely on people to remember what they ate over long periods of time?
Do any animal foods also have anti-angiogenic properties?
Do any studies compare outcomes of cancer patients who treated with diet to those who treated with anti-angiogenic drugs?
Reader Comments (see link above to Dr. Li’s TED Talk via Forks Over Knives)
Peer Reviewed Research
1.Tumor Angiogenesis as a Target for Dietary Cancer Prevention (2012) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3184418/
This is the only peer reviewed article I found directly linking diet to angiogenesis and cancer treatment. Dr. Li from the TED Talk is the first author. It is not a clinical trial, but a review of how specific micronutrients in specific plant foods promote anti-angiogenesis or otherwise inhibit cancer.
First he presents a list of “angiogenic factors” that have been discovered. He then lists “endogenous inhibitors of angiogenesis” that suppress cancer growth. He then describes how genes work to control when new blood vessels are formed. He states that small cancers are common once people reach about 40-50 years of age and that the inhibitors of angiogenesis prevent these cancers from growing too much and becoming dangerous.
Li goes on to describe how some cancers progress to hyperplasia, dysplasia, and then invasive carcinoma by recruiting surrounding blood vessels and enabling new vessels to form. New blood vessels are able to form “by the production and release of one or more angiogenic growth factors…”. He describes how cancers grow and metastasize from there.
Dr. Li discusses current angiogenic therapies that have been proposed and that are in use today. He stresses early treatment before new blood vessels are able to start forming.
Finally, he lists antiangiogenic factors in common foods. For each food, he cites research that supports how they might be preventing cancer in mice, in vitro (test tube), or in human observational epidemiologic or prospective cohort studies. He provides links to all of the studies cited. The factors he describes include:
Green tea catechins, genistein (found in soy beans), resveratrol (found in mulberries, peanuts, grapes, and grape products), lycopene (found in tomatoes, watermelon, and papaya), omega-3 polyunsaturated fatty acids (found in salmon, herring, mackerel, anchovies, sardines and trout), glucosinolates, isothiocynates and indole-3-carbinol (found in cruciferous vegetables such as cabbage, broccoli, cauliflower, collard greens, mustard greens, radishes, brussel sprouts, bok choy, and kale), flavonoids and quercetin (found in many fruits and vegetables), anthocyanins (pigments in berries and grapes), proanthocyanidins (found in cacao and some fruits and vegetables), ellagitannins (found in fruits, vegetables and nuts), manaquinone (vitamin K2 found in dark leafy vegetables and cheese), curcumin (turmeric), beta-cryptoxanthin (found in brightly colored foods).
In the discussion section, Dr. Li does state some of the flaws in the types of studies he reviewed. No human controlled experimental trials have been done. However, he still trusts overall that foods with antiangiogenic factors will help prevent cancer. Interestingly, his paper does not make the claim that these foods work as good as or better than cancer treatments that are already on the market. Instead, he suggests that these foods should be used to help prevent cancer rather than to treat. The paper also never makes bold claims that eating these foods will prevent cancer; only that they may lower one’s chances. Most of the studies he cited showed modest reductions in specific forms of cancer paired with study designs that are known to have high rates of error.
Many other studies address how certain diets can impact cancer. However, I did not find anything other than Dr. Li’s article that claims that the diets are working by inhibiting the growth of new blood vessels. Here are a few reviews, meta-analyses, and one randomized trial I found related to the general question of how diets may cause or help prevent cancer.
2. Influence of a diet very high in vegetables, fruit, and fiber and low in fat on prognosis following treatment for breast cancer: the Women’s Healthy Eating and Living (WHEL) randomized trial. (2007) https://www.ncbi.nlm.nih.gov/pubmed/17635889
CONCLUSION: Among survivors of early stage breast cancer, adoption of a diet that was very high in vegetables, fruit, and fiber and low in fat did not reduce additional breast cancer events or mortality during a 7.3-year follow-up period.
3. Roles of caloric restriction, ketogenic diet and intermittent fasting during initiation, progression and metastasis of cancer in animal models: a systematic review and meta-analysis. (2014) https://www.ncbi.nlm.nih.gov/pubmed/25502434
CONCLUSIONS: Caloric restriction and ketogenic diet are effective against cancer in animal experiments while the role of intermittent fasting is doubtful and still needs exploration. More clinical experiments are needed and more suitable patterns for humans should be investigated.
4. Vegetarian diets, low-meat diets and health: a review. (2012) https://www.ncbi.nlm.nih.gov/pubmed/22717188
RESULTS: Both vegetarian diets and prudent diets allowing small amounts of red meat are associated with reduced risk of diseases, particularly CHD and type 2 diabetes. There is limited evidence of an association between vegetarian diets and cancer prevention. Evidence linking red meat intake, particularly processed meat, and increased risk of CHD, cancer and type 2 diabetes is convincing and provides indirect support for consumption of a plant-based diet.
5. Diet and cancer: risk factors and epidemiological evidence. (2014) https://www.ncbi.nlm.nih.gov/pubmed/24374225
CONCLUSIONS: There is a direct relationship between unhealthy diet and lifestyle with the increase of tumor development and cancer risk. For this reason, a good nutritional status based on a balanced diet constitutes one of the main preventive factors from tumors. However the mixed results from epidemiologic studies hinder to get unequivocal and consistent evidence about the interaction between diet and cancer risk. More epidemiological studies will be needed in the future to clarify this issue.
6. Diet and Colorectal Cancer Risk in Asia–a Systematic Review. https://www.ncbi.nlm.nih.gov/pubmed/26225683
ABSTRACT SELECTION: We found that red meats, processed meats, preserved foods, saturated/animal fats, cholesterol, high sugar foods, spicy foods, tubers or refined carbohydrates have been found by most studies to have a positive association with colorectal cancer risk. Inversely, calcium/dairy foods, vitamin D, general vegetable/fruit/fiber consumption, cruciferous vegetables, soy bean/soy products, selenium, vitamins C,E and B12, lycophene, alpha-carotene, beta-carotene, folic acid and many other vitamins and minerals play a protective role against colorectal cancer risk. Associations of fish and seafood consumption with colorectal cancer risk are still inconclusive due to many varying findings, and require further more detailed studies to pinpoint the actual correlation. There is either a positive or no association for total meat consumption or white meats, however their influence is not as strong as with red and processed meats.
7. Nutrition and cancer. (2015) translated from Spanish https://www.ncbi.nlm.nih.gov/pubmed/26267778
RESULTS: Fruits and vegetables are the foods that can prevent from cancer disease, soya and fishes also have demonstrated as preventive from some types of malignancies. Clear factors causing cancer are red meat and processed meat, dairy products and alcohol. The protective roles of vitamins, antioxidants and micronutrients still have to be deeply investigated. Obesity is a clear risk factor for cancer, calorie reduction has been proposed as a factor that has protective properties in laboratory studies, but this has to be demonstrated in a clinical scenario.
8. Meat, dairy, and cancer. (2014) https://www.ncbi.nlm.nih.gov/pubmed/24847855
ABSTRACT: In 2007 the World Cancer Research Fund and American Institute for Cancer Research (WCRF/AICR) report judged that the evidence for an association between red and processed meat consumption and colorectal cancer was convincing. In addition, the effect of other animal products on cancer risk has been studied, and the WCRF/AICR report concluded that milk probably decreases the risk of colorectal cancer but diets high in calcium probably increase the risk of prostate cancer, whereas there was limited evidence for an association between milk and bladder cancer and insufficient evidence for other cancers. There are several potential mechanisms relating meat to cancer, including heterocyclic amines, polycyclic aromatic hydrocarbons, N-nitroso compounds, and heme iron. Although the evidence in favor of a link between red and processed meat and colorectal cancer is convincing, the relations with other cancers are unclear. In this review, we summarize cohort studies conducted by the National Cancer Institute on meat and dairy intake in relation to cancer since the 2007 WCRF/AICR report. We also report the findings of meta-analyses published since 2007.
9. Dairy products and cancer. (2011) https://www.ncbi.nlm.nih.gov/pubmed/22081693
ABSTRACT SELECTION: Based on a systematic review of the epidemiologic literature, the World Cancer Research Fund and American Institute for Cancer Research report concluded there was a probable association between milk intake and lower risk of colorectal cancer, a probable association between diets high in calcium and increased risk of prostate cancer, and limited evidence of an association between milk intake and lower risk of bladder cancer. For other cancers, the evidence was mixed or lacking.
10. Adherence to Mediterranean diet and risk of cancer: an updated systematic review and meta-analysis of observational studies. (2015)https://www.ncbi.nlm.nih.gov/pubmed/26471010
ABSTRACT SELECTION: The aim of the present systematic review and meta-analysis of observational studies was to gain further insight into the effects of adherence to Mediterranean Diet (MD) on overall cancer mortality, incidence of different types of cancer, and cancer mortality risk in cancer survivors. An overall population of 1,784,404 subjects was included in the present update. The highest adherence score to an MD was significantly associated with a lower risk of all-cause cancer mortality, colorectal cancer, breast cancer, gastric cancer, prostate cancer, liver cancer, head and neck cancer, pancreatic cancer, and respiratory cancer. No significant association could be observed for esophageal/ovarian/endometrial/and bladder cancer, respectively. Among cancer survivors, the association between the adherence to the highest MD category and risk of cancer mortality, and cancer recurrence was not statistically significant. The updated meta-analyses confirm a prominent and consistent inverse association provided by adherence to an MD in relation to cancer mortality and risk of several cancer types.
11. Mediterranean diet and cancer: epidemiological evidence and mechanism of selected aspects. (2013) https://www.ncbi.nlm.nih.gov/pubmed/24267672
DISCUSSION: The most recent pooled analyses of epidemiological studies supported strongly the hypothesis that the Mediterranean diet may play a role in preventing several types of cancers, especially those of digestive tract, whereas contrasting results were reported for hormone-dependent cancers. Specific aspects of the Mediterranean diet such as high fruit and vegetables and low red processed meat intake may explain such protective effects. Moreover, evidence regarding olive oil and whole grains increase the beneficial effects of such dietary pattern against cancer.
12. Nutrition and prostate cancer: an overview. (2014)https://www.ncbi.nlm.nih.gov/pubmed/25367323
ABSTRACT SELECTION: Obesity and metabolic syndrome are important risk factors for prostate cancer and their management is key. The amount and type of fats consumed are also clearly related to prostate cancer risk. Saturated fats and trans fats are identified as having a negative impact. Nutraceuticals and supplements, particularly antioxidants, polyphenols and soy have evidence for benefit for prevention of prostate cancer and progression of the disease.
13. Ketogenic Diet and Cancer-a Perspective. (2016)https://www.ncbi.nlm.nih.gov/pubmed/25503112
ABSTRACT SELECTION: Exercise or severe restriction of caloric intake is not always advisable for patients, in particular those suffering from cancer. The ketogenic diet (KD), characterized by high fat, moderate protein and very low carbohydrate composition can evoke a physiological state similar to that triggered by exercise or fasting. These attributes of KD prompted its possible use in treatment of a number of metabolic diseases, including several types of malignancies. Although results from clinical studies employing KD in the treatment of cancer are still limited, the results obtained from animal models are encouraging and show that KD presents a viable option as an adjunct therapy for cancer.
14. The role of dietary factors in prevention and progression of breast cancer. (2014)https://www.ncbi.nlm.nih.gov/pubmed/25503112
RESULTS: Consumption of well-done red meat appears to be associated with increased risk of BC, whereas fish may be protective. Total cholesterol, triglyceride levels and glycaemic load should be monitored and controlled in at risk populations because they may be associated with increased risk of BC, although the exact mechanisms involved are not clear. Alcohol intake should be minimized since it is a risk factor for BC. High intake of polyphenol/phyto-oestrogen -rich food (i.e. flavonoids, soya products), as well as fibres, fruits and vegetables, may have potential protective effects against BC occurrence but the results might vary according to hormonal status. Vitamin D supplements appear protective against BC development and similarly other vitamins and oligo-elements might decrease BC risk, although further large prospective studies are required.
15. Dietary intake and ovarian cancer risk: a systematic review. (2014)https://www.ncbi.nlm.nih.gov/pubmed/24142805
ABSTRACT SELECTION: Higher risk for ovarian cancer was shown for total, animal, and dairy fat (five of nine studies), as well as total nitrate and possibly total vitamin C. No associations were demonstrated for red meat, fiber, vitamin A, vitamin E, β-carotene, or folate. Vegetables were associated with lower risk in one of three studies; fruit showed no association, although risk estimates were all greater than 1.0. Isoflavones and flavonoids were associated with modestly lower risk in two studies and tea intake was associated with lower risk in one of two studies. This review suggests that no specific dietary factors are consistently associated with ovarian cancer risk.
What we know and don’t know:
After the research, we can see that angiogenesis is a necessary process for cancers to grow and become dangerous. We know there are FDA approved drugs to help slow this process. We also know that people who eat a lot of fruits, vegetables, fish, soy, and tea tend to have lower chances of developing most types of cancer than people who drink a lot of alcohol, eat a lot of red and processed meat, eat a lot of trans and saturated fat, and eat foods cooked at high temperatures. There is quite a bit of data to support these general ideas, but few randomized control trials. That means it may be hard to assign cause and effect and the studies may have other various flaws making them less reliable.
Research does not directly support that eating certain properties of plant foods can prevent cancer from establishing a blood supply. However, the research does not directly deny that this is happening. I wasn’t able to find any studies to directly test this hypothesis. No studies were found that compare treating patients with medication to treating patients with diet.
Even if plants are helping to protect people from cancer by way of antiangiogenic properties, it is highly unlikely that plant foods could replace medications. Dr. Li himself doesn’t even suggest this in his own paper. Additionally, Dr. Li’s research supports consumption of certain animal products such as fish, which is conveniently overlooked when presented by vegan groups.
Another common theme throughout the research in the relationship between cancer and diet is simply that eating less can help. Several studies show that reducing calories lowers the chance of developing cancer and that being overweight is a huge cancer risk factor. Some studies also show that a ketogenic diet can prevent and even help treat cancer. In fact, I was able to find more support for ketogenic diets as a cancer treatment than for vegan or nearly vegan diets.
Conclusions and applications:
What should we do with this information? Here’s my list of ideas based on my research:
- Eat lots of fruits and vegetables every day
- Eat fish several times a week
- Soy products are probably good for you, although this is another hot topic
- Avoid processed meat
- Eat less red meat and opt for cuts that don’t need to be well done
- Avoid processed foods, trans fats and sugar
- Avoid alcohol
- Maintain a healthy weight
- If you already have cancer, traditional treatments work better than a plant-based diet, although a ketogenic diet may be helpful.