Vitamin C Articles
Vitamin C Helps Smokers
Lack of Vitamin C Linked to Respiratory Disorders
Vitamin C Intake Offers Protection Against Stomach Cancer
Vitamins E, C May Counteract Unhealthy Fast Food
New Hope for Sufferers of Age-Related Eye Illness
Vitamins C & E Supplements Protect Lungs
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Vitamin C Helps Smokers
One in three Europeans are smokers. In the US, the estimate is one in five. Tobacco smoke contains over 4,000 compounds, of which 60 are known carcinogens. The oxidative stress levels of smokers are significantly greater than non-smokers, and as such there is a bigger drain on the levels of antioxidants in the body.
A recent study indicates that a daily supplement of vitamin C can help preserve vitamin E levels in smokers. Smokers have high oxidative stress which triggers these low levels of vitamin E.The results also suggest smokers and non-smokers, exposed to second-hand smoke, may benefit from daily intake of vitamin C supplements, although expert advice is clearly to avoid tobacco smoke altogether.
Vitamin E, an antioxidant, actually refers to a group of eight compounds: four types of tocopherols and four tocotrienols. The most common variety consumed in the diet is gamma-tocopherol, while alpha-tocopherol is the variety mostly found in supplements.
Published in the February issue of Free Radical Biology and Medicine, a double-blind, placebo-controlled randomized crossover study followed eleven smokers and 13 non-smokers with an average age of 22. Each were assigned either a vitamin C supplement (500 mg, twice a day) or a placebo (70.5 per cent calcium phosphate, 29.5 per cent cellulose, and 0.5 per cent magnesium stearate for 17 days.
"Supplementation with ascorbic acid [vitamin C] for two weeks effectively reduced the elevated plasma alpha- and gamma-tocopherol disappearance rate observed in cigarette smokers," wrote Richard Bruno, the lead author from Oregon State University.
The researchers explained, "During the placebo trial, smokers' alpha-tocopherol fractional disappearance rate were about 65 per cent faster than non-smokers".
After about two weeks of vitamin C supplements the disappearance of alpha-tocopherol by 25 per cent, regaining vitamin E rates as those found in non-smokers.
"Thus, ascorbic acid supplementation restored smokers' alpha-tocopherol disappearance kinetics to "normal"," wrote Bruno.
The statistics from this study adds to the understanding that increased levels of oxidative species in tobacco smoke increase the oxidative damage to tocopherols, and contribute to the significant disappearance.
The vitamin C works, not by preventing lipid peroxidation that would lead to oxidative stress, but by reducing an oxidized tocopherol moiety, according to the researchers.
The study did not agree with previous reports that antioxidant supplements reduced the level of a marker of oxidative stress, F2-alpha-isoprostane. However, the researchers of the newer study proposed that the short duration, small sample size and younger participants may have affected this marker.
Overall, this study does conclude with other studies that vitamin C can help reduce the disappearance of vitamin E due to tobacco smoke.
"It would seem necessary for smokers to strive to consume a diet that contains at least the RDAs for vitamin E (15mg per day of alpha-tocopherol) and vitamin C (125 and 110 mg per day for male and female smokers, respectively).
In addition, further trials are warranted to determine if other dietary antioxidants can attenuate alpha- and gamma-tocopherol disappearance," concluded Bruno.
Free Radical Biology and Medicine (Vol. 40, pp. 689-697) February 22, 2006
www.nutraingredients.com
Lack of Vitamin C Linked to Respiratory Disorders
A study has found that vitamin C may prevent symptoms associated with airway diseases such as cystic fibrosis, asthma, and chronic obstructive pulmonary disease (COPD). The findings were published in the March 2, 2004, issue of the Proceedings of the [U.S.] National Academy of Sciences.
In the two-year study, researchers discovered that vitamin C supports the normal hydration of airway surfaces, while vitamin C deficiency may lead to dry, sticky mucus membranes lining the airway. Thus, low levels of vitamin C may play a role in the progression of common inflammatory airway diseases by making the airways susceptible to infections. Vitamin C was tested on the function of a cell protein called the cystic fibrosis transmembrane conductance regulator (CFTR). A cystic fibrosis model was also used to examine the role of vitamin C on abnormal CFTR. The findings of cellular testing were confirmed by instilling vitamin C into the nasal passages of healthy human subjects. The results suggest that supplemental vitamin C may improve airway symptoms. A survey by the U.S. Department of Health and Human Services revealed a link between fruit consumption, vitamin C intake, and the risk of asthma. Deficiencies of vitamin C have been reported in the airways of asthmatic patients.
“Vitamin C may prove to be an effective, safe, and low-cost treatment to improve current therapies, including bronchodilators, anti-inflammatory medications, and antibiotics,” noted lead researcher Beate Illek, Ph.D., of the Children’s Hospital & Research Center (Oakland, CA, USA).
www.medinews.com, April 1st, 2004
Vitamin C Intake Offers Protection Against Stomach Cancer
Evidence shows that vitamin C intake and fruit consumption may be linked to reduced risk of stomach cancer. The study also shows that lycopene, an antioxidant found in tomatoes, could have a protective effect against the cancer although the researchers caution that this needs further research.
The team from the US National Cancer Institute and National Public Health Institute of Finland assessed the association between fruit and vegetable consumption and the risk of stomach cancer in approximately 29,000 male smoker participants, aged 50 to 69, of the Alpha-Tocopherol, Beta Carotene (ATBC) cancer prevention study in Finland.
This trial, initiated to test the effect of vitamin supplementation on the prevention of lung and other cancers, ended in 1993 but ongoing follow-up of the participants continues, offering new insights into the causes and prevention of multiple diseases.
Speaking yesterday at this year's Frontiers in Cancer Prevention Research conference (abstract 173), the US and Finnish scientists said they had found fruit and vitamin C intake, but not vegetable consumption, reduced risk of non-cardia cancer approximately 45 per cent.
Non-cardia cancer is the major form of stomach cancer in most parts of the world. Stomach cancer is the second most frequent cause of cancer deaths worldwide, with an estimated 776,000 deaths in 1996, and the fourth most common cancer. In the UK stomach cancer is the sixth most common cancer with 10,000 new cases each year.
"Since our findings are similar to the results found in several other studies, fruit and vitamin C intake are likely to be useful for the prevention of stomach cancer," said Farin Kamangar of the Cancer Prevention Studies Branch at the National Cancer Institute, and one of the lead investigators of the study.
Last year researchers at the San Francisco VA Medical Center found that the lower the level of vitamin C in the blood the more likely a person will become infected by Helicobacter pylori, the bacteria that can cause peptic ulcers and stomach cancer. Although it was not clear whether the presence of the bacteria lowered blood levels of the vitamin, or whether vitamin C levels could protect against it, other studies have also seen low blood levels of vitamin C in people with the cancer.
In Japan, where rates of the cancer are much higher than in the west, researchers have linked a diet of highly salted food containing little vitamin C, with a twofold risk of the cancer.
Another component of fruit, lycopene, which is already associated with reduction of breast and prostate cancer risk, also appeared to lower chances of stomach cancer by 34 per cent. But the effect of lycopene on gastric cancer "needs further studies", warned Dr Kamangar.
Recent research suggests that lycopene may reduce risk of cancer by activating special cancer preventive enzymes, rather than through its antioxidant effect.
When looking at cardia cancer (another part of the stomach), consumption of retinol, a form of vitamin A, was associated with a reduced risk, but the vitamin E forms alpha-tocopherol and gamma-tocopherol seemed to be associated with an increased risk, reported the researchers.
www.nutraingredients.com
18/10/2004
Vitamins E, C May Counteract Unhealthy Fast Food
Researchers have found that high intakes of glucose and high-fat, high-calorie fast food meals both cause an increase in the inflammatory components of the blood.
They also found that an extra dose of antioxidant vitamins E and C can block this inflammatory response in the bloodstream.
"A meal high in calories and fat caused an increase in inflammatory markers that lasted three to four hours," said Dr. Paresh Dandona, a senior endocrinologist at the University of Buffalo School of Medicine and senior author of studies presented Sunday at the annual meeting
of the American Diabetes Association in San Francisco.
Other researchers have noted that eating an unusually heavy or high fat meal may increase a person's risk of a heart attack as much as four-fold, apparently because hormones released into the bloodstream impair the function of the inner linings of the arteries.
Calories, fat, protein, carbohydrates and water, the major components of any food, are considered macronutrients.
Dandona said, "We think the influx of macronutrients may alter cell behavior and that genes are activated to produce more powerful enzymes and mediators that are potentially more damaging to the lining of the blood vessels.
"On the other hand, we found that one way to render an unsafe meal 'safe' is to include antioxidant vitamins," Dandona said. "The pro-inflammatory effect of glucose is stopped if right at the outset you give vitamins E and C."
The study was done with nine healthy subjects who had fasted overnight and then ate a 900-calorie breakfast consisting of a ham-and-egg sandwich and hash browns from a fast food restaurant. Blood samples were taken before they ate and one, two and three
hours afterward to measure the concentration of oxygen-free radicals, molecules that can damage blood vessel linings, and of several blood components that encourage or inhibit inflammation.
There was an average increase of free radicals over the baseline of 129 percent after an hour, 175 percent after two hours and 138 percent after three hours. Levels of blood components that increase inflammation were also up significantly, while levels of a factor that slows inflammation were reduced.
Similar studies showed that influxes of glucose alone, and an infusion of fatty acids, caused a reduction in the ability of blood vessels to expand and contract in response to changes in blood flow, critical for maintaining a healthy blood pressure.
In yet another study, eight subjects took 1,200 International Units of vitamin E and 500 milligrams of vitamin C before ingesting sugar water, and then in a second test took only the glucose.
Blood sampling showed that levels of free radicals and two inflammatory markers increased when glucose was taken alone, but did not increase when the subjects took the antioxidant vitamins beforehand.
On the Net: http://www.diabetes.org
New Hope for Sufferers of Age-Related Eye Illness
Large doses of vitamins C and E, beta carotene and zinc can significantly cut the risk of going blind from the leading cause of vision loss in people 65 and older, says a groundbreaking study out today.
If everyone at high risk for developing advanced age-related macular degeneration, or AMD, took the supplements, more than 250,000 Americans would be saved from going blind over the next 5 years, says study chair Frederick Ferris of the National Eye Institute. About 6 million Americans have moderate AMD, while another 1.8 million have advanced AMD, Ferris says.
No other treatment has been shown to slow or prevent the development of advanced AMD. "This is a rather remarkable finding," says Paul Sieving, director of the eye institute.
The study, reported in the Archives of Ophthalmology, involved 4,757 people, 55 to 80 years old. They were randomly assigned to one of four treatments groups: zinc, antioxidants, antioxidants and zinc, or a placebo. They were followed for about 6 years. The antioxidants consisted of 500 milligrams of vitamin C (about five times what most people get in their diet), 400 international units of vitamin E (13 times the recommended daily amount or RDA) and 15 milligrams of beta carotene. The 80 milligrams of zinc oxide (five times the RDA) was given with copper to prevent anemia.
The study classified subjects with AMD into three categories: early, intermediate or advanced. Those with early disease and most with intermediate had no vision loss. The classifications were based on the size and number of drusen, yellow deposits under the retina that characterize AMD.
In those with intermediate AMD or advanced AMD in one eye, the supplements combining antioxidants and zinc cut the risk of the disease progressing by about 25%. Separately, the antioxidants and zinc provided a smaller benefit.
Gerald Chader, chief scientific officer of the Foundation Fighting Blindness in Owings Mills, Md., says the new findings "are tremendously going to improve the quality of life for a number of people."
None of the treatments cuts the risk of cataracts, the scientists reported in a separate paper. And no benefit from any treatment was seen in subjects with no AMD or early AMD, whose risk of progressing to advanced disease during the study was very low.
Ferris cautioned such individuals against taking the supplements. Although his study saw few side effects, beta carotene can be risky to smokers, while high doses of zinc can cause anemia. Regular exams by an ophthalmologist can determine if and when supplements should be taken to prevent advanced AMD, Ferris says.
USA Today
October 12, 2001
Vitamins C & E Supplements Protect Lungs
Researchers have found that daily doses of vitamin C and E counteract the negative, inflammatory effect on lungs from the pollutant ozone. Previous studies have shown that even low levels of ozone have significant effects on lung function, as little as one hour after exposure. These effects have been previously studied by researchers exercising athletes indoors, under laboratory conditions.
Research teams feel that the antioxidants protect the lungs by reducing the lung's inflammatory response to the pollutants and ozone. Vitamin E and antioxidants are believed to have anticancer effects as well as heart protective benefits.
American Journal of Epidemiology
1999 "Vitamins C And E Supplements Protect Lungs" |
