Lycopene, Naringenin and Chlorogenic Acid—The Health Benefits of Tomatoes

You’ve heard the old saying …“You say toe-MAY-toe and I say toe-MA-toe.” Well, it doesn’t matter how you pronounce tomato because it’s what’s inside that really counts. And, in this case, it’s lycopene and a host of other beneficial nutrients found in this garden favorite. And while we’ll discuss these other nutrients later, let’s first look at the most widely studied compound in tomatoes, lycopene.

Lycopene is a carotenoid that gives tomatoes, watermelon, red grapefruit, papaya, and guava their color. There are more than 600 naturally occurring carotenoids—including beta-carotene—and lycopene seems to offer the most potent antioxidant protection of them all.

However, as we will soon discuss, lycopene is only one of the important components in tomatoes. Research now suggests that it is the combination of lycopene, along with the other phytochemicals in tomatoes that offer the health benefits of a diet rich in tomato products.

What’s the best source of lycopene?

In a word, tomatoes. Tomatoes that are ripened on the vine contain more lycopene than tomatoes that are picked green and then ripened. Even more importantly, cooked tomato products have higher available levels of lycopene than those in raw form because cooking breaks down cell walls, releasing lycopene. And your body absorbs lycopene even more easily if the tomatoes have been cooked in olive oil.¹ So next time you’re cooking tomato sauce, don’t hesitate to pour in some olive oil.

But despite Americans’ love affair with Southern Italian food, it’s a challenge to get the optimal amount of lycopene you need to enjoy its health benefits. Believe it or not, some people are allergic to tomatoes, others find that tomatoes and tomato sauces don’t agree with them and cause indigestion. Still others simply don’t like the taste of tomatoes and are missing out on their health benefits. Lastly, to get enough lycopene to truly ensure you get the protection that it offers, you’d have to eat tomato-based products on a consistent basis.

There’s an easier way to get all the lycopene and other tomato phytochemicals you need to inhibit inflammation and free radical damage, and to protect yourself from developing cardiovascular disease or getting some forms of cancer.

Lycopene has attracted a lot of attention since 1995, when a six-year study by Harvard University of nearly 48,000 men found that those who ate at least 10 servings of foods per week containing tomato sauce or tomatoes were 45% less likely to develop prostate cancer. The study also found that those who ate four to seven servings per week were 20% less likely to develop the cancer.²

Researchers have also found that lycopene may help reduce risk of heart disease. One study found that women who ate at least seven servings a week of tomato-based products had a 30% reduced risk of cardiovascular disease³

You have to admit, those are pretty significant benefits from just eating tomatoes.

Lycopene works synergistically with the other phytochemicals in whole tomatoes to provide a wide range of health benefits. New evidence shows that the protective effects of tomatoes against cancer and cardiovascular disease are due to a combination of lycopene and the other phytonutrients naturally present in the fruit and skin of the tomato.⁴ In other words, you won’t obtain all the nutrients if you skin a tomato before making tomato sauce.

Tomatoes are a potent source of lycopene, but tomatoes are also an excellent source of flavonoids and polyphenols, which are associated with lower cancer risk. In addition, tomatoes contain significant amounts of folate, vitamin C, potassium, as well as some vitamin A and vitamin E.⁵

The important thing to remember is that research has shown that tomatoes contain a lot more than just lycopene. Tomatoes are also a great dietary source of the flavonoid naringenin and the polyphenol chlorogenic acid. Additionally, it has been found that cooking tomatoes greatly increases the absorption of these two important phytochemicals into our bodies.⁶ It seems that while cooking tomatoes can increase lycopene absorption, this is not the whole story of why cooked tomato products are more health protective than uncooked tomatoes. Instead, it also seems evident that cooking tomatoes dramatically increases the bioavailability of both naringenin and chlorogenic acid, and that these tomato compounds act together with lycopene to promote health.

Because of the strong association between dietary cooked tomato products and a lower risk of certain diseases, much research is now being undertaken into what benefits supplements of lycopene may have. Unfortunately, clinical studies utilizing lycopene supplements may end up being disappointing, because typical lycopene extracts do not contain all the valuable phytochemicals found in the tomato.

Lycopene supplements are made using lycopene that is either produced synthetically or extracted from tomatoes. Natural tomato lycopene extracts do contain some other tomato phytochemicals besides lycopene, such as beta-carotene, minor carotenoids, and vitamin E. However, the actual amounts of these additional tomato compounds are small. Lycopene made synthetically contains only lycopene. And in the case of naringenin and chlorogenic acid … typical lycopene extracts and supplements contain no significant amounts.

Tomatoes are more than just lycopene!!

The fact that cooked tomatoes contain significant amounts of absorbable naringenin and chlorogenic acid, while lycopene supplements do not, may well doom clinical studies using current commercial lycopene supplements to disappointing results. This is due to the considerable health benefits already proven in research looking at the effects of naringenin and chlorogenic acid.

“Additionally, naringenin has been proven to possess the unique and amazing ability to actually stimulate DNA repair in prostate cells.” ⁸

In the case of naringenin, this flavonoid has been shown in epidemiological research to be associated with the reduced risk of numerous chronic diseases. Among the diseases for which increased naringenin intake had a beneficial effect are vascular disease and asthma.⁷ Additionally, naringenin has been proven to possess the unique and amazing ability to actually stimulate DNA repair in prostate cells.⁸ This recently documented effect of naringenin on prostate cells may be very important for explaining the ability of cooked tomato products to protect the prostate gland from cancer. This is because the naringenin in raw tomatoes is not well absorbed in humans, but naringenin is well absorbed from cooked tomatoes. Sadly, typical lycopene supplements do not contain naringenin.

“Some of the most exciting research on chlorogenic acid has been on its ability to lower blood pressure in patients with hypertension.”¹⁰¹¹

Like naringenin, chlorogenic acid also has profound beneficial effects. In fact, chlorogenic acid is one of the most abundant health-promoting polyphenol compounds found in our diet, and is the major polyphenol found in tomatoes. Unfortunately, if you don’t eat enough fruits and vegetables, you probably aren’t getting enough chlorogenic acid to obtain its potential health benefits.

Chlorogenic acid is a powerful antioxidant compound, and also has potent anti-inflammatory and anti-cancer effects.9 Some of the most exciting research on chlorogenic acid has been on its ability to lower blood pressure in patients with hypertension.¹⁰¹¹ These studies have shown that chlorogenic acid can significantly decrease blood pressure in patients with mild hypertension … without any side effects! As discussed earlier, cooking tomatoes greatly increases the amount of chlorogenic acid we absorb after eating tomato products. And like naringenin, typical lycopene supplements contain NO chlorogenic acid.

 

Scientific studies on tomatoes

Hundreds of scientific studies have shown that dietary intake of tomatoes, and especially cooked tomato products, are associated with a decreased risk of chronic diseases including cancer and cardiovascular disease. Here are a few of them:

Helping to reduce cancer risk:

Lycopene is well known as a protectant against prostate cancer. In a recent, small intervention trial at the University of Illinois at Chicago, patients with prostate cancer who were scheduled to undergo a prostatectomy ate a daily serving of tomato sauce starting three weeks before surgery. The results were very positive.¹²

“Lycopene’s benefits are not limited to the prostate. Researchers have found that lycopene is likely to play a role in the prevention of other cancers including pancreatic, skin, lung, and breast.”

• The patients’ blood lycopene doubled and the prostate lycopene concentration tripled during this short period. (It’s interesting to note that lycopene is the most abundant carotenoid present in the prostate.)
• Oxidative DNA damage in leukocytes and prostate tissues was significantly diminished, probably due to the antioxidant properties of lycopene. In fact, lycopene’s antioxidant activity is double that of beta-carotene in quenching a particular type of destructive free radical called singlet-oxygen.¹³ Lycopene is also especially effective at protecting lymphocytes from free radical damage.¹⁴
• The researchers were especially surprised by the decrease in blood prostate-specific antigen, which was explained by the increase in death of prostate cells, especially in the cancerous regions.
• Prostate cancer cell cultures were also sensitive to lycopene in vitro, and showed an increase in cancer cell death.

Lycopene’s benefits are not limited to the prostate. Researchers have found that lycopene is likely to play a role in the prevention of other cancers including pancreatic, skin, lung, and breast.

Pancreatic cancer:

In this study researchers investigated the association between dietary carotenoids and pancreatic cancer risk. They looked at 462 patients with pancreatic cancer cases and 4,721 population-based controls. In the end, the dietary intake of lycopene from tomatoes was associated with a 31% reduction in pancreatic cancer risk among men.¹⁵

Skin cancer:

When human volunteers were exposed to UV light, more lycopene in the skin was destroyed compared to beta-carotene, suggesting that lycopene plays a greater role in the protection against UV-induced skin damage compared to beta-carotene.¹⁶

When lycopene was applied topically, it prevented UVB-induced photodamage, reduced an inflammatory response, and prevented DNA damage.¹⁷

Lung cancer:

The human lung is particularly vulnerable to oxidative damage due to ozone and oxidative stress. Researchers have actually found that concentrations of carotenoids in the lung epithelial lining and lining fluids protect against oxidative damage,¹⁸ and that lycopene can even protect smokers from developing lung cancer. In fact, smoking alters the concentrations of most carotenoids, including alpha-carotene and beta-carotene, but not lycopene, indicating that lycopene may play a special role in lung cancer prevention.¹⁹

A study at the Harvard School of Public Health examined the relation between lung cancer risk and intakes of alpha-carotene, beta-carotene, lutein, lycopene, and beta-cryptoxanthin in two large cohorts (an observational study in which outcomes in a group of patients that received an intervention are compared with outcomes in a similar group).

In one group, during a 10-year follow-up period, 275 new cases of lung cancer were diagnosed in 46,924 men. In the second group, during a 12-year follow-up period, 519 new cases were diagnosed in 77,283 women. Based on questionnaires that the participants filled out reporting their fruit and vegetable consumption, the researchers concluded that lung cancer risk was significantly lower in the subjects who consumed a diet high in a variety of carotenoids. And more specifically, alpha-carotene and lycopene intakes were even more significantly associated with a lower risk of lung cancer.²⁰

Breast cancer:

Although more studies need to be done in this area, it appears that lycopene may also inhibit and protect against breast cancer. Researchers at Ben-Gurion University of the Negev, Beer-Sheva, Israel, did a study based on the findings that a high insulin-like growth factor I (IGF-I) blood level is a risk factor in breast and prostate cancer. The purpose of their study was to determine whether lycopene could reduce the activity of IGF-I in breast cancer cells. They found that lycopene inhibited the stimulation of the cancer cells by interfering with the cell cycle (see the section “How does lycopene work?”) of IGF-I.²¹

Reduces inflammation:

Italian researchers at the University of Milan recently reported that a daily glass of a commercial tomato juice can lower one of the primary markers of inflammation—TNF-alpha—by almost 35% in less than one month. Oxidative stress and the by-products of inflammatory compounds such as TNF-alpha have been linked to most chronic degenerative diseases, including atherosclerosis, arthritis, cardiovascular disease, cancer, and Alzheimer’s disease. This tomato juice contains a mix of tomato antioxidants, including 5.7 mg of lycopene.

The placebo-controlled, double blind crossover trial divided 26 young healthy volunteers into two groups. In three 26-day segments the first group was given a placebo juice first (same taste but no active compounds), then nothing, then a daily glass of the tomato juice product. Study subjects continued to eat their normal, unrestricted diet. The results showed that TNF-alpha levels decreased by 34% after drinking the tomato drink for 26 days, while no changes in TNF-alpha levels were seen after drinking the placebo.²²

Essentially what this all means is that lycopene and the other phytochemicals in tomato juice profoundly reduce inflammation in the body, which is a major risk factor for numerous chronic diseases.

Supports cardiovascular health:

Lycopene provides healthy support to your cardiovascular system. Lycopene helps protect cholesterol from being oxidized, and many health professionals believe that it is oxidation of cholesterol in the bloodstream that allows it to stick to the inner lining of the arteries and cause plaque formation.

A large Finish study investigated the relation between serum lycopene concentration and the thickness of the inner lining of the carotid artery (found on each side of your neck) in 1,028 men, aged 46-64, from 1991-1993. A low serum lycopene concentration was associated with a thicker carotid artery, suggesting that the serum lycopene concentration may play a role in the early stages of atherosclerosis. Increased thickness of the inner lining of the carotid artery has been shown to predict stroke and cardiovascular disease; thus, the researchers concluded that lycopene intakes and serum concentrations may have clinical and public health relevance.²³

Reduces cholesterol:

Researchers at the Technion Faculty of Medicine in Haifa, Israel, found that giving a dietary supplement of lycopene to men for a 3-month period resulted in a significant 14% reduction in the men’s plasma LDL cholesterol concentrations.²⁴

Blood pressure:

A recent study at the University of the Negev in Beer Sheva, Israel, evaluated the effect of a tomato extract containing lycopene on systolic and diastolic blood pressure in patients with hypertension, as well as the serum lipoproteins, plasma homocysteine, and oxidative stress markers.

The researchers found that a daily dose of lycopene helped lower blood pressure among 31 men and women with mild hypertension. On average, the subjects’ systolic pressure (the top number in a blood-pressure reading) dropped 10 points, while their diastolic pressure, or bottom number, dipped 4 points.²⁵

May promote longevity in women:

Lycopene may also improve longevity in women. In a study examining plasma lycopene and longevity in nuns, lycopene and other carotenoids were measured in 94 participants, aged 77 to 99 years, living in the same convent. After six years of follow-up, only 13% of those with low plasma lycopene were still alive, while 48% of those with moderate lycopene and 70% of those with high lycopene were living. Life table analyses indicated an 11-year difference in life expectancy between those with low and high plasma lycopene.²⁶  (Life table analysis is a way to present, evaluate, and compare mortality data from study reports.)

This might be explained by the fact that lycopene is an antioxidant that reduces oxidative stress, which plays a major role in numerous health concerns for women including breast cancer, cervical cancer, cardiovascular disease, and preeclampsia.²⁷

Lycopene may help prevent osteoporosis:

One of the more exciting recent discoveries about the relationship between lycopene intake and disease has been in the study of osteoporosis risk. It was found that postmenopausal women with higher intakes of lycopene had lower laboratory markers of bone turnover (a major risk factor for osteoporosis). These women also had decreased levels of oxidative stress when consuming higher levels of lycopene. While it had already been known that lycopene can reduce free radical damage and oxidative stress, the ability of lycopene to protect bone health and possibly be useful against osteoporosis was surprising. This preliminary study led the authors to conclude that, “… these results suggest that the dietary antioxidant lycopene reduces oxidative stress and the levels of bone turnover markers in postmenopausal women, and may be beneficial in reducing the risk of osteoporosis.”²⁸

How does lycopene work?

As we have seen, lycopene is a very potent antioxidant and is associated with a lower risk of chronic disease. Research is showing that in addition to quenching singlet-oxygen molecules, lycopene has other functions as well.²⁹ Lycopene:

• enhances cell-to-cell communication via increasing “gap junctions” between cells.30 This is an important mechanism for cells to communicate with each other, and helps to ensure proper cell and organ functions. It also prevents cancer cells from growing out of control.
• modulates cell-cycle progression. (The cell cycle is a highly ordered set of events, which culminates in cell growth and division. It is tightly controlled by many regulatory mechanisms that either permit or restrain its progression. The use of lycopene appears to be a potential anticancer strategy of regulating the cell cycle by inhibiting abnormal cellular growth.){ref 31}³²

How much lycopene do you need for optimal health?

There have been no studies that define the exact amount of lycopene that is considered the most beneficial for optimal health. However, studies on typical healthy dietary amounts of lycopene, and what we now know about lycopene absorption in humans, can provide us with some intelligent guidance. A typical “healthy” diet contains approximately 5 milligrams of lycopene. Of course, many of us consume much less than this amount. This is especially true of people who don’t eat lots of cooked tomato products, or prefer mainly raw tomatoes.

As important as our daily intake of lycopene is how well lycopene is absorbed. As stated earlier, cooking lycopene in oil (especially olive oil) can increase our absorption of lycopene. Research has also shown that our ability to absorb and utilize lycopene is greatly influenced by the dose of lycopene we consume. Our mechanism to absorb lycopene is “saturated” at relatively low levels of lycopene intake, and larger doses are very poorly absorbed.³³³⁴ This has profound implications for those of us interested in reaping the benefits of lycopene. What these researchers found was that most people can only absorb about 5 milligrams of lycopene from a single dose, regardless of the amount of lycopene consumed. Surprisingly, people absorbed as much lycopene into their bodies from taking 6 milligrams as they did from taking 120 milligrams!

Not only are excessive doses of lycopene not absorbed, but the unabsorbed lycopene also bathes the entire digestive tract with abnormally high levels of lycopene. This may have unknown negative consequences. For most of us eating “typical” diets, supplements of 3 to 6 milligrams of lycopene daily, in addition to what lycopene we get in our diet, is optimal. This will provide us with blood and tissue levels of lycopene that have been shown to be beneficial in numerous human studies.

Total Lycopene Content of Selected Foods
Food	Serving*	Total Lycopene (mg)
Tomato Juice (without salt added)	240 mL (1 cup)	22.9
Tomato Ketchup	15 mL (1 tbsp)	2.9
Spaghetti Sauce	125 g (1/2 cup)	20.0
Tomato Paste	30 g (2 tbsp)	8.8
Tomato Soup (condensed)	245 g (1 cup prepared)	13.1
Tomato Sauce	60 g (1/4 cup)	9.6
Chili Sauce	15 mL (1 tbsp)	2.2
Seafood Cocktail Sauce	60 g (1/4 cup)	7.3
Watermelon	280 g (1/16 of a watermelon)	13.6
Pink Grapefruit	154 g (1/2 medium)	2.3
Raw Tomato	148 g (1 medium)	4.5

Note: while these foods may contain large amounts of lycopene, most of it is absorbed into the body and most people do not eat them on a daily basis.
USDA-NCC Carotenoid Database for U.S. Foods 1998
H.J. Heinz nalytical results
*FDA Reference Amounts; Guidelines for Voluntary Nutrition Labeling of Raw Fruit, Vegetables, and Fish

 

Why should you take a lycopene supplement?

Well first of all, it’s the easiest way to obtain all the benefits of lycopene (unless you want to make tomatoes a major part of your diet). Secondly, lycopene accounts for approximately 50% of the carotenoids in your blood serum. And in contrast to other carotenoids, lycopene levels decrease as we age. Lycopene levels are also affected by smoking or alcohol consumption—which are all important reasons to take a lycopene nutritional supplement!

“Secondly, lycopene accounts for approximately 50% of the carotenoids in your blood serum. And in contrast to other carotenoids, lycopene levels decrease as we age.”

There are lots of lycopene products on the market. How do you decide which one to take?

Most products contain only lycopene, and disregard the other healthy phytochemicals found in tomatoes. Additionally, many products use synthetic lycopene, which is inferior to natural tomato lycopene extracts in its effects. Lycopene supplements usually contain the fat-soluble form of lycopene dissolved in oil, which is very poorly absorbed when taken in high doses.

Here’s what to look for when shopping for a lycopene product:

• Make sure it’s a complete spectrum tomato supplement that supplies a standardized amount of natural lycopene, along with the other phytochemicals (naringenin and chlorogenic acid) found in cooked tomatoes. A reasonable amount of supplemental lycopene to take daily is 3 to 6 milligrams. Taking the lycopene in divided doses will maximize absorption, as will taking the lycopene with meals. Remember that typical lycopene supplements do not contain naringenin or chlorogenic acid. These products will not give the full health benefits of tomatoes because they lack these important tomato phytochemicals that work together with lycopene to promote health.
• Taking supplements that contain dry lycopene beadlets (a powdered form of lycopene), rather than lycopene dissolved in oil, has the advantage of being more dispersible in water. This added benefit should aid absorption and maximize bioavailability. A synergistic supplement such as this ensures excellent absorption, and will give you the high blood levels of lycopene and other healthy tomato compounds which are necessary to obtain the many health benefits of tomatoes.

Conclusion

For years we’ve been hearing how important it is to eat at least five to seven servings of vegetables and fruits each day. Now we know that tomato-based foods are especially beneficial in warding off some types of cancer and cardiovascular disease, and that lycopene can even protect your lungs if you smoke (although we still implore you to quit smoking).

Additionally, study results highlight the importance of how a food is prepared and consumed in determining the bioavailability of dietary carotenoids such as lycopene. Now it’s easier than ever to take a supplement with all the beneficial nutrients that tomatoes have to offer, without worrying about the best possible way to prepare and cook them so that you reap the full benefits.

So, go ahead and indulge in tomato-based foods … but keep in mind that you don’t have to eat them ten times a week. It’s easier and a lot more convenient to take a capsule filled with all the great things found in this beautifully red, gem of a fruit.

References