Comparing Antioxidant Levels in Tomatoes of Different Color

Naturally occurring antioxidants have been of great interest in recent years due to their recognizable health benefits. A study out of Universidad Autónoma Metropolitana in Mexico has clarified differing antioxidant levels by focusing on eight tomato genotypes with different-color fruit.

Laura Pérez-Flores led a team of researchers in an evaluation of the variation in carotenoid, polyphenol, and tocopherol content among selected hybrid and native tomato lines as well as assays for antioxidant capacity of the fruit. In addition, the expression of isoprenoid metabolism-related genes and two pigmentation-related transcription factors were determined.

Pérez-Flores explains, “Tomatoes are the major dietary source of antioxidants; however, little is known about their contents and regulation in genotypes of different colors, shapes, and sizes. The association of greater levels of specific antioxidants with particular colorations of tomato fruit suggests a ‘balance’ between these compounds.”

The findings of these researchers are illuminated in their article “Antioxidant Balance and Regulation in Tomato Genotypes of Different Color”, found in the current issue of the Journal of the American Society for Horticultural Science.

Tomato fruit are an excellent source of antioxidants and contribute significantly to human health because of their anti-inflammatory, antiallergenic, and antithrombotic properties. The results of this study support either the direct commercialization of tomatoes with different color fruit or use of their genotypes in breeding programs to increase antioxidant levels among existing cultivars.

Carotenoids and tocopherols are among the major lipophilic antioxidants present in tomatoes. Polyphenols are powerful antioxidants that have been reported to interfere with the initiation, promotion, and progression of cancer. The main tomato polyphenols are hydroxycinnamic acids, flavanones, flavonols, and anthocyanins.

In recent years, the biosynthetic pathways of carotenoid, tocopherol, and chlorophyll have been studied because of their importance in understanding the regulatory cross-talk that contributes to the nutritional quality of tomato fruit.

The study was conducted in Mexico, which is a center of diversification and domestication of tomato and thus offers a wide range of native genotypes with fruit of different colors, shapes, and sizes. These genotypes could be integrated into breeding programs aiming to increase the nutraceutical properties of commercial cultivars and recover antioxidant compounds that have been lost through the selection process.

All genotypes used in this study were part of the Mexican Network of Plant Genetic Resources. The studied lines, native and hybrid, were planted in a completely randomized block design with three replications, and each experimental unit comprised 10 plants.

The researchers found that greater levels of specific antioxidants were associated with particular colorations of tomato fruit. These genotypes could be used either directly as food or in breeding programs to recover greater levels of functional compounds such as carotenoids, tocopherols, anthocyanins, and vitamin C.

Source: American Society for Horticulture Science


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Antioxidants Don’t Relieve Muscle Soreness After Exercise

Lisa Rapaport wrote . . . . . . . . .

Consuming lots of antioxidants through foods or supplements may not reduce muscle soreness after exercise, a research review suggests.

Researchers focused on “delayed onset muscle soreness,” the type of muscle pain or tenderness that typically peaks 24 to 72 hours after a strenuous workout. Some previous research has linked antioxidants to the prevention of cellular damage that can potentially result in sore muscles, but results have been mixed.

Data for the current analysis came from 50 studies with a total of 1,089 participants, ages 16 to 55. Across all of these studies, researchers didn’t find a meaningful connection between antioxidants in foods or supplements and the amount of muscle soreness at 6, 24, 48, 72, or 96 hours after workouts.

“The findings of our study suggest that antioxidants do reduce soreness, but the effect is so small it may not be meaningful,” said study leader Mayur Ranchordas of Sheffield Hallam University in the U.K.

“People should probably avoid taking antioxidants for recovery,” Ranchordas said by email.

Antioxidant supplements are often marketed in health food stores as a workout recovery aid. The idea that they antioxidants might ease muscle soreness after intense workouts stems from their role in potentially halting or slowing the development of what’s known as oxidative stress, researchers note in the British Journal of Sports Medicine.

As the body uses oxygen, it produces by-products called free radicals that can damage cells and tissues. The damage by oxygen free radicals is known as oxidative stress.

Foods rich in antioxidants include a variety of berries like blueberries, cranberries, goji berries and elderberries as well as dark chocolate, pecans, artichokes and kidney beans.

There are several limitations in the current analysis, including the wide variety of exercise types and intensities as well as the range of different types of antioxidant exposure from foods and supplements, the authors note.

Still, the results suggest that it doesn’t make sense for athletes to spend lots of money on antioxidant supplements to help with recovery from strenuous exercise, said Troy Merry, a nutrition researcher at the University of Auckland in New Zealand who wasn’t involved in the study.

“There are certain strategies that athletes use following exercise to improve recovery such as ice baths, massage, ensuring adequate macronutrients (carbohydrate and protein) intake during and following exercise,” Merry said by email.

“However, how much these strategies actually reduce muscle soreness is debatable, and depends on the type of exercise being undertaken,” Merry added.

The approach to recovery should depend on the type of sport as well as the intensity and frequency of exercise.

“It is also important to consider what the goal of exercise you are undertaking is, as soreness is associated with important processes that cause your muscle to adapt to exercise stress and improve its function overtime,” Merry said. “So if you don’t have to perform at your absolute best in the days following an exercise session, then some soreness is probably good.”

Source: Reuters


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Antioxidant Supplements: Too Much of A Kinda Good Thing

There appears to be a continued public misconception (encouraged by the supplement industry) that free radicals are bad, and that antioxidants are good. Of course, like most phenomena affecting our health, it’s not that simple.

Free radicals are molecules or atoms containing an unpaired electron. Unpaired electrons are attention seekers. They really don’t like being alone, so are always searching out other electrons. This makes them highly reactive. Free radicals are like the unstable friend who shows up drunk to the party and starts breaking things. Antioxidants are molecules that are able to donate an electron to the free radical, thus stabilizing it. They’re like the patient friend who is able to convince the free radical not to drive home, takes him to the back room to calm him down, and brings him water and a bucket once he starts throwing up.

Needless to say, without the presence of antioxidants, free radicals can really ruin the party. The cellular damage that results is called oxidative stress, and is associated with ageing, heart failure, cancer, Alzheimer’s, and many other health problems.

Until recently, the thinking had been that the more antioxidants, the less oxidative stress, because all of those lonely electrons would quickly get paired up before they had the chance to start mucking things up in our cells. But that thinking has changed.

Drs. Cleva Villanueva and Robert Kross published a 2012 review titled “Antioxidant-Induced Stress” in the International Journal of Molecular Sciences. We spoke via Skype about the shifting understanding of antioxidants.

“Free radicals are not really the bad ones or antioxidants the good ones.” Villanueva told me. Their paper explains the process by which antioxidants themselves become reactive, after donating an electron to a free radical. But, in cases when a variety of antioxidants are present, like the way they come naturally in our food, they can act as a cascading buffer for each other as they in turn give up electrons to newly reactive molecules.

“For instance,” Villanueva said, “chocolate has more than 20 antioxidant flavonoids. One is converted into a free radical and becomes reactive, but less reactive [than the first]. It then reacts with another, and that one is less reactive and so on and so forth, and all of them react with each other, decreasing the damage that would be happening to our lipids, or proteins or DNA”

If there is only one type of antioxidant present, say in the case of a high-dose vitamin C supplement, then there are no other antioxidants to provide that protective cascade effect. Then you could end up with a bunch of reactive vitamin C, which itself can cause what they call “antioxidant stress.”

Wait a minute — So a person taking high dose antioxidants might actually be doing the exact opposite of what he or she is trying to accomplish with the supplement? Yes, they said. But it gets even worse.

Free radicals are a natural byproduct of aerobic metabolism in the cells (energy production using oxygen), which ramps up during physical activity. The free radicals produced by this increase in metabolism signal the cell to make its own home-made antioxidants. These endogenous antioxidants are very important, and may be responsible for many of the health benefits associated with physical activity.

A 2014 review published in Nutrition and Food Science called for more research on the subject, but ultimately concluded that high-dose antioxidant supplements can effectively “abolish the beneficial effects of exercise” (emphasis mine). Researchers think that high levels of a single antioxidant (like the 1,000 mg of vitamin C in a packet of Emergen-C) can snatch up all the free radicals produced by exercise before they have a chance to trigger the synthesis of those beneficial endogenous antioxidants.

Barbara Demmig-Adams, professor of ecology and evolutionary biology at the University of Colorado in Boulder, and one of the authors of the 2014 paper wrote in an email:


“I think it’s a really important realization that the much-maligned radicals have a job to do in our bodies and that single high-dose supplements can do more harm than good. . . . . . . Our review on antioxidants and exercise is just the tip of the iceberg. There is a real paradigm shift . . . . . . in the biomedical research area that is causing pioneers to ask, ‘could 50 years of research be wrong?’”


It didn’t take much Googling to discover that over the last few years, this new thinking about antioxidants has indeed enjoyed some coverage. But has this new knowledge really made it through to the public? In a highly unscientific survey, I annoyed my friends over the last few weeks by baiting them with the question: “So what do you think of antioxidants?” Generally the consensus still seemed to be that a vitamin C supplement, say before a cold, was a good idea.

“The best advice is just to eat a proper diet that contains a variety of antioxidants, but don’t go overboard,” said Robert Kross. “Antioxidant supplements are only justified if you have a deficiency,” he explained. The research continues to support this idea—that optimal health comes from moderation and balance. But will we ever really embrace moderation?

Catherine Price wrote the book “Vitamania: Our Obsessive Quest for Nutritional Perfection.”

“We want a hero and a villain,” she told me over the phone. “But it’s actually more about balance. Sometimes [antioxidants] are good, and sometimes [they’re] not good. What are we supposed to do with that?” It’s especially hard for people to wrap their minds around the latest nutrition advice, Price pointed out, because it always seems to be changing.

“It’s so confusing. It speaks to our inability to cope with the uncertainty of science. You have experts for 30 or 40 years saying that margarine is good for us, and then we find that it’s totally untrue, and still there are all these other questions for which we don’t have the answers,” said Price.

So whom should we expect the public to listen to, when we righteously start touting the latest data? By their very nature, scientists are never 100 percent sure about anything. But marketers seem to be so certain about everything they tell us. Not only that, but their messages are simple, and make us feel good:

  • Vitamin C is an antioxidant.
  • Antioxidants are good for you.
  • Drink this, it will make you feel better.

In fact, in the long run, it might make you feel a whole lot worse. Our cells practice an elegant balancing act, each component playing an important part: vitamins, minerals, electrolytes, water, free radicals, other metabolites, antioxidants—both endogenous and dietary. When we figure out a specific beneficial role any one of these serves, it’s tempting to say: “Wow, look how important this thing is, let’s make sure folks get a whole bunch of it!” But that can throw off the whole delicate system, leading to some serious consequences.

We still have much to learn, but here’s a safe bet: usually when something is over 1000 percent of the recommended daily value, it’s probably best to just leave it on the store shelf.

Source: Scientific American

What Are Anthocyanins and Why Are Purple Foods So Healthy?

Sarah Lienard wrote . . . . . .

Antioxidants called anthocyanins have hit headlines and are linked to a range of health benefits. We reveal what they are and which foods contain them.

At BBC Good Food we believe eating a balanced and varied diet, including at least five portions of fruit and vegetables per day, is best for health. But what’s so special about purple foods in particular?

Many purple foods contain anthocyanins

All brightly coloured fruit and vegetables contain antioxidants – compounds which play a key role in protecting our bodies – but many naturally purple-coloured foods contain a certain antioxidant called anthocyanin. These are beneficial plant pigments which give fruit and veg their deep red, purple or blue hues.

While studies are ongoing, it’s too early to say conclusively whether anthocyanins deserve the recent media headlines that label purple foods as ‘superfoods’. Previous research has linked anthocyanins to a wide variety of health claims, including increased longevity, cardiovascular health, cancer prevention and dementia.

Which foods contain anthocyanins?

Anthocyanins are found in high concentrations in blackcurrants, blackberries and blueberries, as well as in aubergine (in the skin), red cabbage, cranberries and cherries.

Blueberries

Blueberries are a useful source of vitamin C, which helps protect cells and aids the absorption of iron, and contain soluble fibre, which is beneficial to the digestive system. Read more about the health benefits of blueberries.

A study in the European Journal of Nutrition found that a supplement containing dried blueberry powder improved brain power in children aged 7 to 10.

Research from Tufts University suggests that consuming a blueberry supplement may be effective in improving or delaying short-term memory loss in rats.

However, the NHS points out that the existing studies into how blueberries might prevent cancer or improve memory have so far relied on small sample groups or animals, and it is not yet clear whether these findings will translate to larger groups of the human population. Read more from the NHS about the nutritional benefits of blueberries.

Pomegranate

Somewhere in between red and purple, the jewel-like colour of pomegranate is thanks to its anthocyanin content. Pomegranate is a good source of fibre, and also provides vitamins A, C and E, iron, and other antioxidants such as tannins.

One study found that pomegranate helped to strengthen bones and prevent osteoporosis in mice through decreased inflammation and oxidative stress.

Another study found that consuming 50ml of pomegranate juice per day reduced damage to arteries and cut cholesterol build-up in people with narrowed arteries.

A further study found that a daily glass of pomegranate juice improved blood flow to the heart, resulting in a lower risk of heart attack. However, the NHS points out that as it was a very limited trial these positive results could have been down to chance.

Purple sweet potato

Purple sweet potatoes have recently been in the media spotlight. They are commonly eaten on the Japanese island of Okinawa, which is home to an exceptionally healthy elderly population – with a large number over the age of 100, and rates of dementia reported to be up to 50% lower than in the West. Some scientists think that the large quantities of purple sweet potato in their diet plays a key role in keeping their bodies and brains healthy well into old age. However, to date, there are not many studies into the health benefits of the purple sweet potato, and it’s impossible to say that the Okinawan’s longevity is down to this one food alone.

A note on beetroot

Beetroot’s deep purple colour comes from plant chemicals called betalains. Like anthocyanins, betalains have antioxidant and anti-inflammatory properties. You can also find betalains in the stems of chard and rhubarb but it’s the flesh and skin of beetroots which are especially rich in them.

Beetroot is also a good source of vitamins and minerals, including folate, iron, manganese and potassium. They’re also nitrate-rich, which contributes to many of beetroot’s perceived health benefits. For example, a study from 2013 found that consuming beetroot juice was linked with lower blood pressure.

Beetroot juice has also been found to moderately improve athletic performance.

Another study has suggested that a diet that includes beetroot juice may increase blood flow to the brain, which some have interpreted to mean it may help prevent or improve dementia. However, as the NHS points out, these findings are limited by the fact that it was based on a very small sample size of 16 elderly people over an extremely short interval. This means that much more evidence is needed before we can conclusively say that beetroot juice aids cognitive function.

So should we be eating more purple foods?

There’s no doubt that naturally purple-coloured fruit and vegetables are an excellent addition to a varied diet, but it’s also important to remember that balance is key and include a rainbow of different colours of fruits and vegetables for optimum health benefits.

Source: BBC

Mushrooms May Slow Aging

Ana Sandoiu wrote . . . . . .

A new study published in the journal Food Chemistry suggests that certain mushrooms contain two antioxidants thought to improve healthspan and stave off aging.

The new research was led by Robert Beelman, professor emeritus of food science and director of the Pennsylvania State University Center for Plant and Mushroom Products for Health in State College. Michael D. Kalaras, a postdoctoral assistant in food science, is the first author of the paper.

Researchers were already aware that mushrooms are “the highest source” of an antioxidant called ergothioneine, but little was known about glutathione, another major antioxidant.

Additionally, levels of antioxidants vary across different species of mushroom, so the researchers wanted to know which species had the most of these two chemicals.

The new findings are significant in the context of the so-called free radical theory of aging. As Prof. Beelman explains, “[The theory] has been around for a long time [and it] says when we oxidize our food to produce energy there’s a number of free radicals that are produced that are side products of that action and many of these are quite toxic.”

“The body has mechanisms to control most of them,” he goes on to say, “including ergothioneine and glutathione, but eventually enough accrue to cause damage, which has been associated with many of the diseases of aging, like cancer, coronary heart disease, and Alzheimer’s.”

However, it is worth mentioning that the free radical theory of aging is controversial. Some rodent studies have shown that by removing free radicals from cells, they can extend the lifespan of the animals.

That being said, other studies have failed to show that supplementing the body with antioxidants can do the same — although the chances of living disease-free until the end of the maximum lifespan have been shown to increase with antioxidants.

Porcini mushrooms richest in antioxidants

Prof. Beelman summarizes the findings of his research, saying, “What we found is that, without a doubt, mushrooms are [the] highest dietary source of these two antioxidants taken together, and that some types are really packed with both of them.”

“We found that the porcini has the highest, by far, of any we tested,” he adds. The researchers tested 13 species.

More common species of mushroom, on the other hand, had less of the two antioxidants. White button mushrooms, for instance, had a low concentration of the antioxidants, although it was still higher than in other foods.

Additionally, the study found a correlation between ergothioneine and glutathione, as mushrooms that had high concentrations in one also had high levels of the other. Prof. Beelman also noted that cooking the mushrooms should not alter the antioxidants, as the compounds are “very heat stable.”

He went on to suggest that future studies ought to look into the effects of these two antioxidants on neurodegenerative disorders.

He says, “It’s preliminary, but you can see that countries that have more ergothioneine in their diets, countries like France and Italy, also have lower incidences of neurodegenerative diseases.”

However, Prof. Beelman adds, “People in countries like the United States, which has low amounts of ergothioneine in the diet, have a higher probability of diseases like Parkinson’s disease and Alzheimer’s.”

“Whether that’s just a correlation or causative, we don’t know,” he admits. “But,” he continues, “it’s something to look into, especially because the difference between the countries with low rates of neurodegenerative diseases is about 3 milligrams per day, which is about five button mushrooms each day.”

Source: Medical News Today