Vitamin E tied to higher risk of prostate cancer
Men taking daily vitamin E were more likely to get prostate cancer than those not taking the dietary supplement, according to a study of close to 35,000 North Americans.
This means that over a decade, one or two men out of 100 taking vitamin E would be expected to get prostate cancer, said the researchers, whose findings were published in the Journal of the American Medical Association.
“If you have enough of these vitamins in your system…extra doesn’t help you any, and too much of something like this can be harmful,” said Eric Klein from the Cleveland Clinic, one of the study’s authors, to Reuters Health.
The findings come on the heels of a study suggesting that older women who take multivitamins have slightly increased death rates compared to those who don’t.
“There’s a theme here that taking vitamins is not only not helpful but could be harmful” in people who are not deficient in vitamins, Klein added.
But one researcher who wasn’t part of the new study said he doubted it means vitamin E causes prostate cancer.
“It’s an interesting finding. I’m not sure I believe it,” said Neil Fleshner, from the University of Toronto, adding that the result may have been a chance finding or false positive.
For the study, men in the United States, Canada and Puerto Rico were randomly assigned to one of four groups. Starting between 2001 and 2004, about 9,000 men in each group took daily supplements of 400 international units (IU) of vitamin E, 200 micrograms of selenium, vitamin E and selenium together or a vitamin-free placebo pill.
The study was halted in late 2008 when the researchers saw a hint of an increased risk of prostate cancer in the men taking vitamin E. But they kept monitoring men for cancer after they stopped taking the supplements. It turned out that the extra risk became clearer over time.
By mid-2011, about seven percent of men who had taken vitamin E only had gotten prostate cancer, compared to six percent of those assigned to placebo pills.
The researchers did not find an extra risk of prostate cancer in men who took only selenium or vitamin E together with selenium.
Klein and his colleagues said it’s not clear how vitamin E would increase the risk of prostate cancer, and that not all past studies have shown it does any harm to the prostate. Some have even found a lower prostate-cancer risk with vitamin E.
He added that the new findings aren’t definite proof that vitamin E causes extra prostate cancers, but that there wasn’t anything else that could explain why men taking the vitamin were more likely to be diagnosed with cancer — for example, they weren’t screened more frequently.
The supplement doses, he added, are much higher than what’s in most over-the-counter multivitamins, which typically contain 15 to 25 IU of vitamin E.
Fleshner said that either way, vitamin E doesn’t seem to be beneficial for prostate health.
“There’s certainly no major evidence that vitamin E helps, so why bother?” he said.
While vitamin supplements are known to prevent disease in people who have vitamin deficiencies, so far studies haven’t found much extra benefit in people who already get enough vitamins through their diet. Specifically, vitamin E has not been shown to protect against heart disease, colon cancer or lung cancer.
On the other hand, there is a growing body of evidence suggesting supplements may be harmful in high doses.
“Vitamins are not innocuous substances,” Klein said.
—— END ——
Source > Reuters-路透社，October 12, 2011
Translated by > BlogHost
Word Count > approx. 600 words in English
Taking vitamin E linked to osteoporosis: Japanese research
Japanese scientists say they have found a link between consumption of vitamin E and the degenerative bone condition osteoporosis, in a study likely to shed new light on the use of supplements.
Researchers found that giving mice increased doses of the vitamin to a level similar to that found in supplements caused the animals’ bones to thin.
The mice developed osteoporosis after eight weeks on the diet, which had levels of vitamin E significantly higher than those found in a mouse’s natural diet, according to the study, published in the journal Nature Medicine.
The team, led by Shu Takeda of Keio University, said vitamin E stimulates the generation of bone-degrading cells, which normally work with bone-forming cells to maintain bone strength.
Osteoporosis is a disease that causes the thinning of bone tissue and loss of bone density over time. It often affects older people, particularly women, who may become more prone to bone fractures.
Vitamin E is found naturally in various foods including vegetable oil, nuts and some leafy vegetables.
It is also a popular health supplement as an antioxidant, and is widely believed to enhance health and slow problems related to ageing.
The study called for greater research into how enhanced levels of vitamin E affect human health.
“It is possible that with the volume (of vitamin E) contained in health supplements, bones may become fragile,” Takeda told the Mainichi Shimbun newspaper.
The findings come after researchers found mice that had been genetically modified to be deficient in vitamin E had a high bone density.
—— END ——
Source > Agence France-Presse-法新社, March 6, 2012
Translated by > BlogHost
Word Count > approx. 280 words in English
Vitamin D supplements can lower risk of dying
Boosting the level of vitamin D by using supplements for someone who is vitamin D deficient can lower his risk of dying by 60 percent, a new study found.
Analyzing data on 10,889 patients, University of Kansas Hospital researchers found that 70 percent of them were deficient in vitamin D, with levels below the 30 nanograms per millilitre considered necessary for good health.
After taking into account the patients’ medical history, medication and other factors, the cardiologists found that people with deficient levels of vitamin D were more than twice as likely to have diabetes. 40 per cent more likely to have high blood pressure and about 30 percent more likely to suffer from cardiomyopathy-diseased heart muscle-as people without this deficiency.
Overall, those who were deficient in vitamin D had a three-fold higher likelihood of dying from any cause than those who were not deficient, the researchers reported in the American Journal of Cardiology.
When the tem look at people who took vitamin D supplements, their risk of death from any cause was about 60 per cent lower than the rest of the patients, although the effect was strongest among those who were vitamin D deficient at the time they were tested.
Vitamin D deficiency has been linked to a range of illnesses, but few studies have demonstrated that supplements could prevent those diseases.
Dr.James L.Vacek, a professor of cardiology at the University of Kansas Hospital and Medical Center, said : “We expected to see a relationship between heart disease and vitamin D deficiency; we were surprised at how strong it was.”
堪萨斯州大学医院和医疗中心心脏病科教授Dr.James L. Vacek说：“我们有准备看到心脏疾病和维生素D缺乏症之间的关系，但关联之紧密让我们感到惊讶。”
But the study does not prove that vitamin D is the cause of the effects seen. Other factors, such as disease, could be responsible both for the differences in health and the differences in vitamin D levels.
Still, people should get about 90 per cent of vitamin D from the sun and about 10 per cent from food, Dr Vacek said.
The human body makes vitamin D in response to skin exposure to sunlight. At least 10 minutes of full-body exposure to sunlight each day is required to get a sufficient amount of vitamin D, Dr Vacek said.
Certain types of food, such as oily fish, eggs and enriched milk products, are also good sources of vitamin D.
The findings mean that adults should consider getting their vitamin D levels checked through a simple blood test and take vitamin D supplements if they are deficient, said Dr Vacek.
He said: “If you’re not deficient, vitamin D is not a magic pill that will make you live longer. Its benefit is in people who are deficient.”
—— END ——
Source > Newspaper Article
Translated by > BlogHost
Word Count > approx. 500 words in English
Side Effects of Becoming a Vegetarian
A vegetarian diet is a healthy choice if you pay attention to nutritional requirements and follow a balanced eating plan. The Mayo Clinic created a vegetarian food pyramid that recommends daily food intake of six servings of grains, five servings of nuts, beans, legumes and other protein foods, four servings of vegetables, two of fruit and two of unsaturated fats. (See References 5) Inattention to dietary needs can create side effects that are unpleasant and unhealthy. For vegans, who avoid all animal products, countering potential dietary deficiencies is particularly important.
Vitamin B12 Deficiency 缺乏维生素B12
If you are a strict vegetarian and eat no dairy, eggs or other animal products, your diet may be deficient in vitamin B12. Symptoms of vitamin B12 deficiency include anemia, weakness, poor balance and tingling in the arms and legs, according to the University of Maryland Medical Center. B12 is important for metabolism, maintenance of the central nervous system and the formation of red blood cells. Vegetarian sources of B12 include fortified grains and nutritional yeast, as well as vitamin supplements. (See References 1)
Iron Deficiency 缺铁性贫血
The most readily absorbed iron is available in foods many vegetarians do not consume: red meats, poultry and fish. A lack of sufficient iron can cause anemia. Symptoms of low iron include exhaustion, weakness, slow cognitive development, chills and increased susceptibility to infection. Women who suffer from iron deficiency can give birth to premature or low birth weight infants. But the type of iron found in beans, lentils, enriched grains, spinach, raisins and tofu is adequate for normal nutritional needs. The National Institutes for Health recommends that vegetarians get twice as much iron as non-vegetarians because the type of iron they consume is more difficult to absorb. NIH advises vegetarians to increase iron absorption by taking vitamin C or consuming citrus with plant-based iron sources. (See References 4)
Zinc Deficiency 缺锌
Zinc helps you to smell and taste. It’s also important for the immune system — zinc helps wounds heal, is a factor in cell division and cell growth and contributes to the process of carbohydrate break down. Zinc is found in high protein foods like meats and dark meat poultry, so vegans and many vegetarians can develop a zinc deficiency. That could result in poor appetite, frequent infections, hair loss and a host of other symptoms. One good way for vegetarians to consume zinc is by eating legumes, peanuts and peanut butter, although zinc from animal protein is more readily absorbed by the body. (See References 3)
Calcium and Bone Loss 钙和骨质的流失
Strong bones need calcium and one of the best ways to get it is from dairy products. If milk, yogurt and butter aren’t part of your diet, look for cereals, breads and juices that have added calcium, fortified tofu, kale, broccoli and Chinese cabbage. Calcium shortages can lead to thinning bone density and osteoporosis, dental problems and other medical conditions. Calcium helps blood to circulate through the body, muscles to move, nerves to transmit messages from the brain, and it releases hormones and enzymes. The NIH points out that calcium supplements can interfere with some medications so you should check with your health care provider before adding supplements to any diet. (See References 6)
1. University of Maryland Medical Center: Vitamin B12 — Side Effects
2. University of Maryland Medical Center: Vitamin B12 Benefits
3. University of Maryland Medical Center: Zinc in Diet — All Information
4. National Institutes for Health Office of Dietary Supplements: Iron
5. Mayo Clinic: Vegetarian Diet: How to Get the Best Nutrition
6. National Institutes for Health Office of Dietary Supplements: Calcium
by Benna Crawford, Demand Media 由BennaCrawford点播媒体提供
—— END ——
Source > National Geographic Environment 国家地理杂志环境版
Translated by > BlogHost
Word Count > approx. 620 words in English
Vegetarian diet: How to get the best nutrition
A well-planned vegetarian diet is a healthy way to meet your nutritional needs. Find out what you need to know about a plant-based diet.
You may follow a vegetarian diet for cultural, religious or ethical reasons. Or you may eat a vegetarian diet to stay healthy and prevent health problems, such as cardiovascular disease. Whatever your reasons for choosing a vegetarian diet, this guide will help you make smart choices to ensure that you meet your daily nutritional needs.
Indeed, a well-planned vegetarian diet can meet the needs of people of all ages, including children, teenagers, and pregnant or breast-feeding women. The key is to be aware of your nutritional needs so that you plan a diet that meets them. If you aren’t sure how to create a vegetarian diet that’s right for you, talk with your doctor and a registered dietitian.
Types of vegetarian diets 素食的种类
When people think about a vegetarian diet, they typically think about a diet that doesn’t include meat, poultry or fish. But vegetarian diets can be further categorized into three types:
Vegan diets exclude meat, poultry, fish, eggs and dairy products — and foods that contain these products.
Lacto-vegetarian diets exclude meat, fish, poultry and eggs, as well as foods that contain them. Dairy products, such as milk, cheese, yogurt and butter, are allowed in a lacto-vegetarian diet.
Lacto-ovo vegetarian diets exclude meat, fish and poultry, but allow eggs and dairy products.
Some people follow a semivegetarian diet — also called a flexitarian diet — which is primarily a plant-based diet but includes meat, dairy, eggs, poultry and fish on occasion or in small quantities.
Getting adequate nutrition 摄取足够的营养
The key to a healthy vegetarian diet — like any diet — is to enjoy a variety of foods. No single food can provide all the nutrients your body needs. The more restrictive a diet is, the more challenging it is to get all the nutrients you need. A vegan diet, for example, eliminates food sources of vitamin B-12, as well as milk products, which are good sources of calcium. Therefore, you may need to make an extra effort to ensure that your vegetarian diet includes sufficient quantities of the following nutrients:
Calcium helps build and maintain strong teeth and bones. Milk and low-fat dairy foods are highest in calcium. Dark green vegetables, such as turnip and collard greens, kale and broccoli, are good plant sources when eaten in sufficient quantities. Calcium-enriched and fortified products, including juices, cereals, soy milk, soy yogurt and tofu, are other options.
Iodine is a component in thyroid hormones, which help regulate metabolism, growth and function of many key organs, such as the brain, heart, kidney and thyroid. Vegans may not consume enough iodine and be at risk of iodine deficiency and possibly goiter. In addition, foods such as soybeans, cruciferous vegetables and sweet potatoes may promote goiter. Because food manufacturers may not use iodized salt in processed foods, vegans may want to ensure that they use salt with iodine at the table or in cooking. Just 1/4 teaspoon provides a significant amount of iodine.
Iron is a crucial component of red blood cells. Dried beans and peas, lentils, enriched cereals, whole-grain products, dark leafy green vegetables and dried fruit are good sources of iron. Because iron isn’t as easily absorbed from plant sources, the recommended intake of iron for vegetarians is almost double that recommended for nonvegetarians. To help your body absorb iron, eat foods rich in vitamin C, such as strawberries, citrus fruits, tomatoes, cabbage and broccoli, at the same time as you’re eating iron-containing foods.
Omega-3 fatty acids are important for cardiovascular health as well as eye and brain development. Vegetarian diets that do not include fish and eggs are generally low in active forms of omega-3 fats. Because conversion of the plant-based omega-3 to the types used by humans is inefficient, you may want to consider fortified products or supplements or both.
Protein helps maintain healthy skin, bones, muscles and organs. Eggs and dairy products are good sources, and you don’t need to eat large amounts to meet your protein needs. You can also get sufficient protein from plant-based foods if you eat a variety of them throughout the day. Plant sources include soy products and meat substitutes, legumes, lentils, nuts, seeds and whole grains.
Vitamin B-12 is necessary to produce red blood cells and prevent anemia. This vitamin is found almost exclusively in animal products, so it can be difficult to get enough B-12 on a vegan diet. Vitamin B-12 deficiency may go undetected in people who eat a vegan diet. This is because the vegan diet is rich in a vitamin called folate, which may mask deficiency in vitamin B-12 until severe problems occur. For this reason, it’s important for vegans to consider vitamin supplements, vitamin-enriched cereals and fortified soy products.
Vitamin D plays an important role in bone health. Vitamin D is added to cow’s milk, some brands of soy and rice milk (be sure to check the label), and some cereals and margarines. However, if you don’t eat enough fortified foods and have limited sun exposure, you may need supplementation with vitamin D-2 (derived from plants).
Zinc is an essential component of many enzymes and plays a role in cell division and in formation of proteins. Like iron, zinc is not as easily absorbed from plant sources as it is from animal products. Cheese is a good option if you eat dairy products. Plant sources of zinc include whole grains, soy products, legumes, nuts and wheat germ.
Getting started 入门
If you’re not following a vegetarian diet but you’re thinking of trying it, here are some ideas to help you get started:
Ramp up 逐步提高
Each week increase the number of meatless meals you already enjoy, such as spaghetti with tomato sauce or vegetable stir-fry.
Learn to substitute 学会取代
Take favorite recipes and try them without meat. For example, make vegetarian chili by leaving out the ground beef and adding an extra can of black beans. Or make fajitas using extra-firm tofu rather than chicken. You may be surprised to find that many dishes require only simple substitutions.
Branch out 分支出去
Scan the Internet for vegetarian menus. Buy or borrow vegetarian cookbooks. Check out ethnic restaurants to sample new vegetarian cuisines. The more variety you bring to your vegetarian diet, the more likely you’ll be to meet all your nutritional needs.
By Mayo Clinic staff 。Mayo诊所的员工撰文
—— END ——
Source > National Geographic Environment 国家地理杂志环境版
Translated by > BlogHost
Word Count > approx. 1080 words in English