The case for extra virgin olive oil improving prostate health

Populations in countries that would naturally consume a traditional Mediterranean diet, which means the diet would include EVOO, tend to have lower rates of a number of cancers, including prostate cancer. There is unfortunately not a lot of data assessing the impact of EVOO on prostate health, but men in Greece and Spain consuming a traditional olive oil enriched Mediterranean diet have lower rates of prostate cancer compared to Caucasian males in non-Mediterranean countries.¹ Despite the lack of specific data linking daily EVOO intake to prostate health, the following presents the potential role of EVOO in decreasing prostate cancer risk by examining the risk factors for prostate cancer that EVOO has been shown to improve.

Fasting blood levels of glucose and insulin: Tumor cells use blood glucose to grow and excess blood glucose has been related to increasing the risk of some cancers however the relationship of excess blood glucose has not been consistently related to elevated risk of prostate cancer. Yet, higher fasting blood glucose has been related to significantly increasing the risk of mortality in men diagnosed with prostate cancer.² For example, a study in men diagnosed with prostate cancer measured A1c at baseline found that having an A1c greater than 6.5% at baseline was the strongest predictor of cardiovascular death or non- fatal heart attack in 13 years of follow-up.³ Note: A1c measures blood glucose control for the prior three months; a diagnosis of type 2 diabetes is made when the value is 6.2% or higher.

Excess blood glucose results from insulin resistance, which means the hormone insulin that we make in our pancreas is not working properly. The result is higher blood levels of both glucose and insulin as the pancreas produces more insulin to try and lower the blood glucose. Higher blood levels of insulin that result from insulin resistance have been shown to increase the risk of prostate cancer developing.⁴ A retrospective analysis of insulin levels in Swedish men who developed prostate cancer found fasting insulin levels to be higher at baseline in those who developed prostate cancer, compared to those who did not develop prostate cancer.⁵ This study is interesting because the baseline insulin level of the men who developed prostate cancer was 12.0 mU/l, a level that is considered well below the clinical cutoff for excess fasting insulin, compared 9 mU/l for the men who did not develop prostate cancer. In Finnish men followed for an average of nine years, those who developed prostate cancer had fasting insulin at baseline 8% greater than those who did not developing prostate cancer.⁶ Again, the values for insulin in this study were also in the normal range. These studies suggest that prostate health is improved with fasting insulin levels being as low as possible.

Insulin resistance is the basis for the metabolic syndrome, and having the metabolic syndrome increases the risk of being diagnosed with high grade prostate cancer but not low-grade prostate cancer.⁷ Insulin resistance if left untreated will lead to type 2 diabetes, and type 2 diabetes has been related to increasing the risk of prostate cancer progression and mortality among obese men but not among nonobese men.⁸

Note: It is blood glucose, which is a type of carbohydrate, that has been related to increasing prostate cancer risk, not carbohydrate found in food. There is nothing harmful in consuming foods that contain carbohydrate.

Daily consumption of at least two tablespoons a day of EVOO has been shown to lower both blood glucose^{9 10 11} and improve insulin sensitivity as indirectly measured by HOMA-IR.^{12 13 14} Thus daily consuming EVOO will improve your blood levels of both insulin and glucose, which would lead to decreasing your risk of the metabolic syndrome, type 2 DM, and possibly prostate cancer.

Oxidation: We cannot stop oxidation due to our basic need of oxygen, but excess oxidation increases aging and the risk of all chronic diseases and cancer. Oxidation is increased with polyunsaturated fats as they can readily breakdown or oxidize, high levels of which are found in vegetable seed oils (corn, safflower, soybean) and beef. Oxidation is minimized with monounsaturated fat, which is the main type of fat in EVOO. Thus, using mainly EVOO means you will have less oxidation in your body compared to frequent consumption of vegetable seed oils and beef. In addition, daily use of EVOO will decrease overall oxidation in your body.^{15 16}

Inflammation: Inflammation plays a key role in prostate cancer development, progression, and metastasis.¹⁷ Daily consumption of extra virgin olive oil has been shown to decrease inflammation compared to a low-fat diet.¹⁸ The phenol content of the EVOO is key to decreasing inflammation as shown in a study comparing an olive oil with 320 mg/ kg total phenols to olive oil with 86 mg/kg total phenols.¹⁹ After three weeks of daily consumption of each olive oil, only the olive oil with 320 mg/kg total phenols decreased inflammation. Body weight: Studies that assess large groups of men indicate that while obesity, as measured by BMI, does not seem to increase the risk of being diagnosed with prostate cancer, it does seem to increase the risk of dying from prostate cancer and also increases the risk of overall death after prostate cancer diagnosis.^{20 21}

Being obese before prostate cancer diagnosis or after diagnosis has also been related to greatly increases the risk of cardiovascular disease death.²² Where you store your excess body fat seems to be important as shown by data indicating that a large waist circumference can increase risk of prostate cancer regardless of BMI. Storing excess body fat at the waist has long been associated with increasing the risk of insulin resistance, the metabolic syndrome, type 2 diabetes, heart disease and a number of cancers. Waist circumference is used to indirectly measure abdominal obesity, which can indicate how much interior (visceral fat) a person has.

Visceral fat surrounds the organs, especially the liver, and leads to insulin resistance. A waist that is more than 40 inches (102 cm) for a male is considered unhealthy. Extra virgin olive oil is a very useful component of a diet to improve your body weight. If you do not have enough fat in a meal, you do not feel satisfied after eating the meal and you will be hungrier sooner than eating a meal with sufficient fat. Compared to following a diet lower in fat for weight loss, a diet rich in EVOO can lead to better weight loss.^{23 24} A study comparing a weight loss diet that included daily soybean oil, a diet that daily included approximately two tablespoons of EVOO resulted in the same weight loss, but the EVOO diet produced more overall fat loss ²⁵ , which I find intriguing. In another study comparing weight loss with a low-fat diet to one with daily EVOO, the diet that including daily EVOO resulted in both greater weight loss and also a larger decrease waist circumference compared to the lower fat diet that did not include EVOO. The plant-based olive oil diet I developed and is explained on this website includes a daily intake of at least three tablespoons of extra virgin olive oil used in meal preparation, preferably with vegetable preparation, and I found to be effective in weight loss and acceptability in research protocols compared to lower fat diets.²⁶

Vegetables and EVOO: Carotenoids provide the colors of red, orange, and yellow to plant products. The deeper the color, the more carotenoid in the food. Sufficient blood levels of carotenoids have been related to a lower risk of a number of cancers. Carotenoids need dietary fat present to be absorbed ²⁷ as they are brought into the body by the particles we make in the intestinal tract to absorb fat, which are called the chylomicron. The more fat that is eaten with the carotenoid containing vegetable, the more carotenoids that are absorbed as more chylomicrons are made. A study comparing cooking tomatoes in EVOO compared to just adding the olive oil to the tomatoes before consuming found that there was significantly more lycopene absorbed when the tomatoes were cooked into olive oil.²⁸ So cooking your dark vegetables in fat will make sure that the carotenoid enters into your blood. Using EVOO to prepare your vegetables will provide you with both a healthy fat and means that the carotenoids in your vegetables will be absorbed into your blood so they will be available for decreasing cancer risk. Cooking vegetables in extra virgin olive oil also makes them taste a lot better and may increase how frequently you consume vegetables. I recommend the use of at least one tablespoon of EVOO per cup of vegetables.

Summary:

EVOO when consumed daily could decrease prostate cancer risk and/ or progression by decreasing fasting levels of blood glucose and insulin, oxidation, inflammation, and body weight. In addition, use of EVOO to prepare vegetables will make sure that the carotenoids found in dark vegetables will enter the body and be available for decreasing overall cancer risk.