Archives for May 2012

Researchers Find Potential ‘Dark Side’ to Diets High in Beta-Carotene

New research suggests that there could be health hazards associated with consuming excessive amounts of beta-carotene.

This antioxidant is a naturally occurring pigment that gives color to foods such as carrots, sweet potatoes and certain greens. It also converts to vitamin A, and foods and supplements are the only sources for this essential nutrient.

But scientists at Ohio State University have found that certain molecules that derive from beta-carotene have an opposite effect in the body: They actually block some actions of vitamin A, which is critical to human vision, bone and skin health, metabolism and immune function.

Because these molecules derive from beta-carotene, researchers predict that a large amount of this antioxidant is accompanied by a larger amount of these anti-vitamin-A molecules, as well.

Professor Earl Harrison

Vitamin A provides its health benefits by activating hundreds of genes. This means that if compounds contained in a typical source of the vitamin are actually lowering its activity instead of promoting its benefits, too much beta-carotene could paradoxically result in too little vitamin A.

The findings also might explain why, in a decades-old clinical trial, more people who were heavily supplemented with beta-carotene ended up with lung cancer than did research participants who took no beta-carotene at all. The trial was ended early because of that unexpected outcome.

The scientists aren’t recommending against eating foods high in beta-carotene, and they are continuing their studies to determine what environmental and biological conditions are most likely to lead to these molecules’ production.

“We determined that these compounds are in foods, they’re present under normal circumstances, and they’re pretty routinely found in blood in humans, and therefore they may represent a dark side of beta-carotene,” said Earl Harrison, Dean’s Distinguished Professor ofHuman Nutrition at Ohio State and lead author of the study. “These materials definitely have anti-vitamin-A properties, and they could basically disrupt or at least affect the whole body metabolism and action of vitamin A. But we have to study them further to know for sure.”

The study is scheduled for publication in the May 4, 2012, issue of theJournal of Biological Chemistry.

Previous research has already established that when beta-carotene is metabolized, it is broken in half by an enzyme, which produces two vitamin A molecules.

In this new study, the Ohio State researchers showed that some of these molecules are produced when beta-carotene is broken in a different place by processes that are not yet fully understood and act to antagonize vitamin A.

Harrison is an expert in the study of antioxidants called carotenoids, which give certain fruits and vegetables their distinctive colors. Carotenoids’ antioxidant properties are associated with protecting cells and regulating cell growth and death, all of which play a role in multiple disease processes.

For this work, he joined forces with co-authors Robert Curley, professor of medicinal chemistry and pharmacognosy, and Steven Schwartz, professor of food science and technology, both at Ohio State. Curley specializes in producing synthetic molecules in the pursuit of drug development, and Schwartz is an expert at carotenoid analysis.

Curley manufactured a series of beta-carotene-derived molecules in the lab that match those that exist in nature. The researchers then exposed these molecules to conditions mimicking their metabolism and action in the body.

Of the 11 synthetic molecules produced, five appeared to function as inhibitors of vitamin A action based on how they interacted with receptors that would normally launch the function of vitamin A molecules.

“The original idea was that maybe these compounds work the way vitamin A works, by activating what are called retinoic acid receptors. What we found was they don’t activate those receptors. Instead, they inhibit activation of the receptor by retinoic acid,” Curley said. “From a drug point of view, vitamin A would be called an agonist that activates a particular pathway, and these are antagonists. They compete for the site where the agonist binds, but they don’t activate the site. They inhibit the activation that would normally be expected to occur.”

Once that role was defined, the researchers sought to determine how prevalent these molecular components might be in the human body. Analyzing blood samples obtained from six healthy human volunteers, the scientists in the Schwartz lab found that some of these anti-vitamin-A molecules were present in every sample studied, suggesting that they are a common product of beta-carotene metabolism.

The compounds also have been found previously in cantaloupe and other orange-fleshed melons, suggesting humans might even absorb these molecules directly from their diet.

Harrison noted that the findings might explain the outcome of a well-known clinical trial that has left scientists puzzled for years. In that trial, people at high risk for lung cancer – smokers and asbestos workers – were given massive doses of beta-carotene over a long period of time in an attempt to lower that risk. The trial ended early because more supplemented participants developed cancer than did those who received no beta-carotene. This outcome was reinforced by results of a follow-up animal study.

“Those trials are still sending shockwaves 20 years later to the scientific community,” said Harrison, also an investigator in Ohio State’s Comprehensive Cancer Center. “What we found provides a plausible explanation of why larger amounts of beta-carotene might have led to unexpected effects in these trials.”

The research also has implications for efforts to bio-engineer staple crops in developing countries so they contain excess beta-carotene, which is considered a sustainable way to provide these populations with pro-vitamin A. Existing projects include production of golden rice in Asia, golden maize in South America and cassava in Africa.

“A concern is that if you engineer these crops to have unusually high levels of beta-carotene, they might also have high levels of these compounds,” Harrison said.

The researchers are continuing to study these compounds, including whether food processing or specific biological processes affect their prevalence. Previous studies have suggested that oxidative stress, which can result from smoking and air pollution exposure, can lead to higher production of these anti-vitamin-A molecules, Harrison noted.

This research was supported by the National Institutes of Health and the Ohio Agricultural Research and Development Center.

Additional co-authors include Abdulkerim Eroglu, Carlo dela Sena and Sureshbabu Narayanasamy of the Department of Human Nutrition; Damian Hruszkewycz of the College of Pharmacy; and Ken Riedl and Rachel Kopec of the Department of Food Science and Technology, all at Ohio State. Harrison, Curley, Eroglu and dela Sena also are affiliated with Ohio State’s Biochemistry Program.

 

Vitamin E in Diet Protects Against Many Cancers

Researchers find form commonly used in supplements has no such benefit. 

Vitamin E in vegetable oils and nuts prevents cancer, according to research done at Rutgers University and the Cancer Institute of New Jersey.

Next time you need to choose between vegetable oil and margarine in that favorite recipe, think about your health and reach for the oil.

While the question of whether vitamin E prevents or promotes cancer has been widely debated in scientific journals and in the news media, scientists at the Center for Cancer Prevention Research, at Rutgers Mario School of Pharmacy, and the Cancer Institute of New Jersey, believe that two forms of vitamin E – gamma and delta-tocopherols – found in soybean, canola and corn oils as well as nuts do prevent colon, lung, breast and prostate cancers.

“There are studies suggesting that vitamin E actually increases the risk of cancer and decreases bone density,” says Chung S. Yang, director of the center. “Our message is that the vitamin E form of gamma-tocopherols, the most abundant form of vitamin E in the American diet, and delta-tocopherols, also found in vegetable oils, are beneficial in preventing cancers while the form of vitamin E, alpha- tocopherol, the most commonly used in vitamin E supplements, has no such benefit.”

Director of the Center for Cancer Prevention Research at Rutgers Ernest Mario School of Pharmacy

Yang and colleagues, Nanjoo Suh and Ah-Ng Tony Kong, summarized their findings recently in Cancer Prevention Research, a journal of the American Association for Cancer Research. In a Commentary, Does Vitamin E Prevent or Promote Cancer? the Rutgers scientists discuss animal studies done at Rutgers as well as human epidemiological studies that have examined the connection between vitamin E and cancer.

Yang says Rutgers scientists conducting animal studies for colon, lung, breast and prostate cancer found that the forms of vitamin E in vegetable oils, gamma and delta-tocopherols, prevent cancer formation and growth in animal models.

“When animals are exposed to cancer-causing substances, the group that was fed these tocopherols in their diet had fewer and smaller tumors,” Yang says. “When cancer cells were injected into mice these tocopherols also slowed down the development of tumors.”

In researching colon cancer, Yang pointed to another recently published paper in Cancer Prevention Research indicating that the delta-tocopherol form of vitamin E was more effective than other forms of vitamin E in suppressing the development of colon cancer in rats.

This is good news for cancer research. Recently, in one of the largest prostate cancer clinical trials in the United States and Canada, scientists found that the most commonly used form of vitamin E supplements, alpha-tocopherol, not only did not prevent prostate cancer, but its use significantly increased the risk of this disease among healthy men.

This is why, Yang says, it is important to distinguish between the different forms of vitamin E and conduct more research on its cancer preventive and other biological effects.

“For people who think that they need to take vitamin E supplements,” Yang says, “taking a mixture of vitamin E that resembles what is in our diet would be the most prudent supplement to take.”

 

Reference

Yang CS, Suh N, Kong AN. Does Vitamin E Prevent or Promote Cancer? Cancer Prev Res (Phila). 2012 Apr 16. [Epub ahead of print]

 

How Probiotic Bacteria Protect Against Inflammatory Bowel Diseases

A glimpse through the laser microscope – green indicates the presence of inflammatory messenger substances (chemokines) in the bowel tissue. Picture: TUM

Some lactic acid bacteria can alleviate inflammation and therefore prevent intestinal disorders. Scientists have now decoded the biochemical mechanism that lies behind the protective effect of the bacteria. In experiments with mice, the researchers succeeded in demonstrating that lactocepin – an enzyme produced by certain lactic acid bacteria – selectively degrades inflammatory mediators in diseased tissue. This new evidence might lead to new approaches for the treatment of inflammatory bowel diseases.

Yoghurt has been valued for centuries for its health-promoting effects. These effects are thought to be mediated by the lactic acid bacteria typically contained in yoghurt. Evidence from recent scientific studies show that some bacterial strains actually have a probiotic effect and can thus prevent disease. A team of biologists and nutrition scientists working with Prof. Dirk Haller from the Technische Universitaet Muenchen (TUM) has now discovered the mechanisms at work behind this protective effect (Cell Host & Microbe).

In experiments with mice, the scientists observed that lactocepin – an enzyme produced from the lactic acid bacterium Lactobacillus paracasei – can selectively interrupt inflammatory processes. As the scientists observed, lactocepin degrades messengers from the immune system, known as chemokines, in the diseased tissue. As a part of the “normal” immune response, chemokines are needed to guide defense cells to the source of the infection. In chronic intestinal disorders like Crohn’s disease and ulcerative colitis, the otherwise highly effective defense mechanism against infectious agents is malfunctioning. Chemokines such as “IP-10” then contribute to the tissue damage due to chronic inflammatory processes,  preventing the tissue from healing.

“Lactocepin is a familiar element in food technology research,” says Prof. Dirk Haller, who holds the Chair for Biofunctionality of Food at the TUM. “What is surprising, however, is its biomedical effect, namely the force with which the enzyme attacks and degrades very specific inflammatory mediators.” Haller is certain that, based on this mechanism, it will be possible to develop new approaches to the targeted prevention and treatment of chronic bowel diseases as well as skin disorders: “The anti-inflammatory effect of lactocepin is limited to specific areas and up to now it has no known side effects.”

The scientist therefore plans to carry out clinical studies in order to test the possible pharmaceutical application of the enzyme. Questions also remain to be answered in relation to the “production” of lactocepin by lactic acid bacteria. Some bacterial strains, such as Lactobacillus paracasei, produce highly potent lactocepins; however, the effectiveness of other microorganisms has not yet been proven. Dirk Haller therefore warns against false promises: “Not every product labeled as ‘probiotic’ actually earns this name.”

Reference 
von Schillde MA, Hörmannsperger G, Weiher M, Alpert CA, Hahne H, Bäuerl C, van Huynegem K, Steidler L, Hrncir T, Pérez-Martínez G, Kuster B, Haller D. Lactocepin Secreted By Lactobacillus Exerts Anti-Inflammatory Effects By Selectively Degrading Proinflammatory Chemokines. Cell Host & Microbe 2012; 11 (4): 387–396.

 

Hungry for Change

We all want more energy, an ideal body and beautiful younger looking skin. So what is stopping us from getting this?

From the creators of the best-selling documentary Food Matters comes another hard-hitting film certain to rock your world.

Hungry for Change (2012) exposes shocking secrets the diet, weightloss and food industry don’t want you to know about; deceptive strategies designed to keep you coming back for more. Find out what’s keeping you from having the body and health you deserve and how to escape the diet trap forever.

Featuring interviews with best selling health authors and leading medical experts plus real life transformational stories with those who know what it’s like to be sick and overweight. Learn from those who have been there before and continue your health journey today.

 Learn More

www.hungryforchange.tv (Official Website)

10 Step Action Guide. Make these simple additions to your life and watch your health improve. You can even print this out and put this on your fridge!

Jon Gabriel’s Evening Visualisation. Listen and learn how to apply the principles of visualisation as discussed in the film with visualisation expert Jon Gabriel.

Food Matters is a hard hitting, fast paced look at our current state of health. It is a feature length documentary film informing you on the best choices you can make for you and your family’s health.

The Food Matters Detox and Rejuvenation Guide is an informative guide that will teach you how to apply the principles addressed in the film. This instantly downloadable e-Book will help you find better alternatives for the foods your body might not agree with, giving you the tools and skills necessary to prepare more nutritious meals.

Food Matters the Recipe e-Book. If you’ve watched Hungry For Change and Food Matters and you are looking for ways to incorporate the lessons from these films into your daily life then this book is for you. The idea is that once you start adding these recipes into your life on a daily basis you will start feeling better and this will encourage you to keep eating this way!