A tomato a day keeps the doctor away....
The many health benefits of tomatoes
Tomatoes are a late summer staple. Their peak season is from July to September so now is the time for enjoying their bounty. In my opinion there is nothing to compare to the delicious sweetness of a homegrown, summer tomato. And I'm happy to report that there are some pretty sweet health benefits as well.
Perhaps you will have read news reports on the benefits of lycopene. Lycopene is a powerful antioxidant with some pretty strong research showing it to be helpful in preventing and treating many serious diseases. Tomatoes are our major source of lycopene. In fact over 80% of the lycopene we eat comes from tomatoes.
But tomatoes are so much more than just lycopene. The many nutrients inside a tomato are felt to work together in a special synergistic way. Although lycopene has gotten a lot of positive press, it is not the whole story.
Tomatoes also contain high amounts of other antioxidants, vitamin C, vitamin A, B6, niacin, folate, and fiber.
The antioxidants are key. Antioxidants act in the body to scoop up harmful free radicals and neutralize them. Free radicals left alone act to injure cells and cell membranes. High antioxidant intake has been associated with decreased progression of coronary artery disease, diabetes, asthma, and colon cancer. Antioxidants also act to prevent cancer in the body.
Lycopene is the main antioxidant in tomatoes. Lycopene acts to give tomatoes their red color. It is also found in watermelons, guava, passionflower, blood oranges, and papaya.
Other important antioxidants and phytonutrients in tomatoes include quercitin, lutein, beta carotene, and gamma carotene.
Let's look at some specific research findings on tomatoes and disease.
By far the strongest evidence is for prostate cancer. A prospective dietary study looked at 47,000 cancer free men from 1982 to 1992. Blood levels of lycopene were compared to new diagnosis of prostate cancer during that time period. Men with the highest levels of lycopene had the lowest risk for prostate cancer (the same was not found for blood levels of other antioxidants such as alpha or beta carotene.
A meta-analysis of 21 different studies (published in Cancer Epidemiology Biomarkers and Prevention) confirmed that eating tomatoes (especially cooked tomatoes) protects men against prostate cancer. Looking at the data from all 21 studies they found that men who ate the highest amount of raw tomatoes had an 11% decrease in prostate cancer risk. And men who ate the most cooked tomatoes had a 19% reduction in prostate cancer risk.
Cooked tomatoes are known to have a higher concentration of lycopene than raw ones.
Lycopene alone is not the whole story though. In an animal study looking at rats with prostate cancer the researchers found that rats given lycopene supplements did not have any decrease in cancer progression. However the rats given tomato powder did show decreased death rate from prostate cancer.
Prostate cancer affects millions of Americans. In 2011 there have been over 240,000 new cased diagnosed and over 30,000 deaths. Prostate cancer can either be a slow growing or "low grade" tumor or a more rapidly progressive "high grade" tumor. Older men with low grade tumors sometimes choose "watchful waiting" instead of surgery. Why not educate these men to enjoy plenty of cooked tomatoes?
As with all things in diet, balance is key. Dozens of observational studies have shown that people who eat diets high in carotene rich fruits and vegetables have less risk for all kinds of cancer (prostate, lung, stomach, breast, colon). There are over 700 types of carotenoids and of those about 50 are active in the body. So it's a good idea to get a variety of different ones. I recommend my health counseling clients "eat a rainbow." When shopping for produce be sure you are getting a variety of different colors.
The importance of this was shown in another study where researchers found that combining tomatoes and broccoli seemed to have a synergistic effect on prostate cancer.
II. Tomatoes and Heart Health:
Research has also shown that diets high in tomatoes and lycopene help to both prevent and slow progression of coronary artery disease.
In a study from Brigham and Women's Hospital involving 4,000 women over 7 years. The participants were free of any heart disease at the onset of the study. They found that women who ate 7 to 10 servings of lycopene rich foods per week had a 29% decreased risk of developing coronary artery disease compared to women who ate less than 1.5 servings a week.
Other epidemiological studies have shown and inverse ratio of serum lycopene levels and mortality from coronary artery disease, stroke, and heart attack.
Lycopene has been shown to protect LDL cholesterol from oxidation. "Oxidized" LDL contributes to plaque formation in arteries and puts one at risk for heart attack.
In addition to lycopene tomatoes are also rich in heart healthy vitamins such as B6, niacin, and folate. And they also have a good amount of potassium. Diets including potassium rich foods have been linked to decreased blood pressure and lower risk for heart disease.
Another way tomatoes may be protecting the heart is via an effect on platelets. Sticky platelets are also involved in arterial plaque formation. An study looking at tomato juice showed regular intake of that juice seemed to reduce platelet stickiness.
Finally, regular use of tomato products has been shown to decrease inflammation in the body. We now know that there is a big inflammatory component to heart disease.
Research done in Italy with tomato juice showed decreased levels of TNF-alpha (a blood marker of inflammation). Another study done at Tufts University showed that eating 1 cup of gazpacho daily for 2 weeks resulted in increased vitamin C levels and decreased oxidative stress in the body.
Chronic inflammation has been linked to many other diseases as well including cancer, alzheimer's, osteoporosis, etc. A tomato rich diet is one way to cool the flames of chronic inflammation.
This is an eye disease which is a major cause of vision loss. The antioxidant Lutein is highly concentrated in the eye and protects it from disease. Tomatoes are a good source of lutein. There have not been research studies looking specifically at tomatoes and lutein, however your eyes will definitely benefit from a diet rich in antioxidants. Tomatoes make a nice addition to a healthy diet.
Skin Protection: Antioxidant effects from tomatoes have been hypothesized to protect the skin from ultraviolet damage. There have been some small, studies suggesting a protective effect against sunburns when lycopene levels are high in the blood.
Diabetes: An interesting study looked at lycopene blood levels in several different patient groups: 1,000 people with normal blood sugar, 277 people with impaired glucose tolerance (sometimes called "borderline diabetes"), 148 newly diagnosed diabetics, and 230 previously diagnosed diabetics. High levels of lycopene in the blood correlated with lower fasting insulin levels. This is important because type 2 diabetes is caused by a resistance in the body to it's own insulin. High fasting insulin levels are a sign of insulin resistance.
Tomatoes are also high in chromium, a mineral that helps to keep blood sugar well controlled.
Eating more tomatoes will help keep your serum lycopene levels up and provide you with a symphony of healthy vitamins, minerals, and phytonutrients.
To learn more about how to reap the health benefits of tomatoes read on to this month's "food focus" column.
Don't like tomatoes? That's okay. Just be sure to get plenty of other "red" foods like watermelon, guava, blood orange, etc.
And remember tomatoes are only part of a healthy diet. We need a variety of different antioxidants and vitamins to keep our bodies humming. Be sure to eat all the colors of the rainbow to keep yourself healthy, happy, and balanced.
prostate cancer link-- Newsweek
prostate cancer link--Herbal Gram. American Botanical council
prostate cancer link--consumerlab.com
prostate cancer link--harvard.edu
Heart Disease link--Herbalgram
lycopene link--herbalgram, herbclip285
carotenoid link. Herbalgram, herbclip 251
Willet, Walter. "Eat, Drink, And Be Healthy"
Colbin, Ann Marie. "Food and Healing"