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Tag: beta-carotene

Published on Leave a comment on Vegetables and Fruits Linked to Eye Health

A new study that tracked people more than 20 years found that a diet high in carotenoids - found in brightly colored fruits and vegetables (such as carrots, orange peppers, spinach, broccoli) - is linked to lower levels of macular degenaration (an age linked vision ailment).

Note that the link is found with real foods and not supplements (the researchers did not look at supplements). From Medical Xpress:

Carrots do help aging eyes, study shows

Your parents may have told you, "Eat your carrots, they're good for your eyes," and a new study suggests they were on to something. Pigments called carotenoids—which give red or orange hues to carrots, sweet potatoes and orange peppers, or deep greens to produce like spinach, broccoli and kale—may help ward off the age-linked vision ailment known as macular degeneration, researchers said.

Age-related macular degeneration (AMD) is one of the most common causes of vision loss, especially in the elderly. It affects the macula, the center part of the retina, and can lead to declines in sharp central vision and even blindness, experts say. 

Scientists have already linked a variety of factors to the condition including genetics, smoking and nutrition, said Bernstein, who was not involved in the new study. Prior research has produced mixed findings about links between carotenoids and macular degeneration, the researchers said. 

In the new study, Wu's team looked at data from health surveys that tracked people aged 50 and older—more than 63,000 women and almost 39,000 men—from 1984 or 1986 until 2010. Participants were all nurses and other health professionals. Overall, about 2.5 percent of study participants developed either intermediate or advanced forms of the eye condition during the years of the study.

Wu's team found that people who consumed the very highest levels of carotenoids known as lutein and zeaxanthin had a 40 percent lower risk of the advanced form of AMD compared to those who ate the veryleast. " Other carotenoids, including beta cryptoxanthin, alpha carotene and beta carotene, may also play protective roles," Wu added. People who consumed the very highest amount of these carotenoids—found in foods such as carrots and sweet potato—had a 25 to 35 percent lower risk of the advanced form of the illness, the findings showed.

Researchers did not find any link between the carotenoids and the intermediate form of macular degeneration, however. Lutein is found in eggs and dark leafy vegetables including broccoli, kale and spinach, Bernstein said. Zeaxanthin is harder to find in the diet, he said, but you can get it from corn, orange peppers and goji berries. Wu noted that both lutein and zeaxanthin concentrate in the macula, where they are thought to protect it from damage from oxygen and light.

Bernstein cautioned that the study has some weaknesses. It's based on people's recollections of their diets, he said, and doesn't examine the levels of the carotenoids that actually made it into their bodies and eyes. Still, he praised the research.... However, he said, a diet high in fruits and vegetables is important, especially colorful vegetables. Consume several servings a day, he advised.

Published on Leave a comment on Don’t Feed Melanoma

This study, even though done on mice, reinforces previous research that taking antioxidant supplements are linked to higher rates of cancer or the spread of cancer (metastases). Here it is linked to the spread of metastatic skin cancer. The researchers say that the overall conclusion from the various studies is that antioxidants protect healthy cells from free radicals that can turn them into malignancies, but may also protect a tumor once it has developed. They also suggest that suntan lotions and skin lotions containing vitamin E and beta-carotene may have the same negative effect and are now studying that possibility. However, note that many, many studies find that eating foods does NOT find negative effects, but only beneficial ones for health. The October 5, 2015 post also discussed why supplements containing large doses of antioxidants (such as beta-carotene) don't work, and can even cause harm. Bottom line: Eat fruits and vegetables daily for numerous health benefits, but skip the antioxidant supplements. From Science Daily:

Antioxidants cause malignant melanoma to metastasize faster

Antioxidants can double the rate of melanoma metastasis in mice, new research shows. The results reinforce previous findings that antioxidants hasten the progression of lung cancer. People with cancer or an elevated risk of developing the disease should avoid nutritional supplements that contain antioxidants, the researchers say.

Researchers at Sahlgrenska Academy, University of Gothenburg, demonstrated in January 2014 that antioxidants hastened and aggravated the progression of lung cancer. Mice that were given antioxidants developed additional and more aggressive tumors. Experiments on human lung cancer cells confirmed the results. Given well-established evidence that free radicals can cause cancer, the research community had simply assumed that antioxidants, which destroy them, provide protection against the disease. Found in many nutritional supplements, antioxidants are widely marketed as a means of preventing cancer. Because the lung cancer studies called the collective wisdom into question, they attracted a great deal of attention.

The follow-up studies at Sahlgrenska Academy have now found that antioxidants double the rate of metastasis in malignant melanoma, the most perilous type of skin cancer. Science Translational Medicine published the findings on October 7. "As opposed to the lung cancer studies, the primary melanoma tumor was not affected," Professor Bergö says. "But the antioxidant boosted the ability of the tumor cells to metastasize, an even more serious problem because metastasis is the cause of death in the case of melanoma. The primary tumor is not dangerous per se and is usually removed."

Experiments on cell cultures from patients with malignant melanoma confirmed the new results. "We have demonstrated that antioxidants promote the progression of cancer in at least two different ways," Professor Bergö says. The overall conclusion from the various studies is that antioxidants protect healthy cells from free radicals that can turn them into malignancies but may also protect a tumor once it has developed.

Avoid supplements: Taking nutritional supplements containing antioxidants may unintentionally hasten the progression of a small tumor or premalignant lesion, neither of which is possible to detect. "Previous research at Sahlgrenska Academy has indicated that cancer patients are particularly prone to take supplements containing antioxidants," Dr. Bergö says. Our current research combined with information from large clinical trials with antioxidants suggests that people who have been recently diagnosed with cancer should avoid such supplements."

The role of antioxidants is particularly relevant in the case of melanoma, not only because melanoma cells are known to be sensitive to free radicals but because the cells can be exposed to antioxidants by non-dietary means as well. "Skin and suntan lotions sometimes contain beta carotene or vitamin E, both of which could potentially affect malignant melanoma cells in the same way as antioxidants in nutritional supplements," Professor Bergö says. How antioxidants in lotions affect the course of malignant melanoma is currently being explored. "We are testing whether antioxidants applied directly to malignant melanoma cells in mice hasten the progression of cancer in the same way as their dietary counterparts," Professor Bergö says. 

Published on Leave a comment on Forget the Pills, Eat the Vegetables Instead

An article that discusses why supplements containing large doses of antioxidants, or beta-carotene, or even vitamin megadoses  doesn't work, and can even cause harm, while eating actual foods such as fruits and vegetables has many health benefits. This is what a number of the studies I've been posting also found (especially with health benefits from eating fish and not from fish oil). go ahead and throw out the megadose supplements, and instead eat lots of fruits and vegetables. Remember fruits and vegetables contain a complex mix of nutrients and feed our microbial communities, as well as having microbes on them. From Medical Xpress:

Forget the antioxidant pills; just stick with veggies

Why just stick to eating fruits and veggies when you can get an extra boost from supplements that put good things like antioxidants into a handy pill? And that seems like it should be a good idea. If the antioxidants that occur naturally in our food, like broccoli and carrots, are good for us, a supplement with the same thing must also be good. But that's not quite true.

Antioxidants are touted as protectors of our health because they eliminate free-radicals that damage molecules in cells and tissues by grabbing electrons from them, making those molecules, in turn, unstable....On this basis, a group of scientists proposed in 1981 the creation of a nutritional supplement to fight free-radicals. They reasoned that since many observational epidemiological studies had shown that people who eat lots of vegetables are at lower risk of colon cancer, heart disease and many other bad conditions, then the "active" ingredient should be identified and put into a pill. They thought that it must be beta-carotene, which helps make carrots orange, because it's an antioxidant.

But in the late 1980s, two intervention trials, one in Seattle and the other in Finland, started....For the Seattle trial, approximately 18,000 men and women were randomized in 1988 to receive either a tablet containing beta-carotene or a tablet containing no active ingredient, which is the famous placebo. The plan was to follow the men and women for 10 years; the researchers hypothesized they would observe a lower lung cancer risk in the beta-carotene tablet group, hopefully much lower. But the opposite happened and the trial had to be stopped early because the beta-carotene group suffered significantly more cases of lung cancer than the placebo group. The same thing was seen in the Finland trial. Importantly, the amount of beta-carotene in the tablet was much higher than occurs naturally in the body in both trials.   ...continue reading "Forget the Pills, Eat the Vegetables Instead"

Published on

Eating green leafy vegetables and other brightly colored fruits and vegetables containing vitamin K, lutein, folate and beta-carotene were linked to keeping the brain healthy in older adults and slowing cognitive decline. Researchers found that older people who ate one to two servings per day had the cognitive ability of a person 11 years younger than those who consumed none. From Science Daily:

Eating green leafy vegetables keeps mental abilities sharp

Something as easy as adding more spinach, kale, collards and mustard greens to your diet could help slow cognitive decline, according to new research. The study also examined the nutrients responsible for the effect, linking vitamin K consumption to slower cognitive decline for the first time...."Since declining cognitive ability is central to Alzheimer's disease and dementias, increasing consumption of green leafy vegetables could offer a very simple, affordable and non-invasive way of potentially protecting your brain from Alzheimer's disease and dementia."

The researchers tracked the diets and cognitive abilities of more than 950 older adults for an average of five years and saw a significant decrease in the rate of cognitive decline for study participants who consumed greater amounts of green leafy vegetables. People who ate one to two servings per day had the cognitive ability of a person 11 years younger than those who consumed none. When the researchers examined individual nutrients linked with slowing cognitive decline, they found that vitamin K, lutein, folate and beta-carotene were most likely helping to keep the brain healthy.

To conduct the study, Morris' research team gathered data from 954 participants from the Memory and Aging Project, which aims to identify factors associated with the maintenance of cognitive health. The participants, whose age averaged 81, reported their daily food and beverage intake by answering a detailed 144-item questionnaire at the beginning of the study.... They followed participants for 2 to 10 years, assessing cognition annually with a comprehensive battery of 19 tests and adjusted for age, sex, education, smoking, genetic risk for Alzheimer's disease and participation in physical activities when estimating the effects of diet on cognitive decline.

"With baby boomers approaching old age, there is huge public demand for lifestyle behaviors that can ward off loss of memory and other cognitive abilities with age," said Morris. "Our study provides evidence that eating green leafy vegetables and other foods rich in vitamin K, lutein and beta-carotene can help to keep the brain healthy to preserve functioning." In addition to green leafy vegetables, other good sources of vitamin K, lutein, folate and beta-carotene include brightly colored fruits and vegetables.