Antioxidants (抗氧化剂) in coffee are thought to help protect against stroke — but too much must raise blood pressure, which increases the risk, according to Japanese researchers. Similarly, green tea could also be beneficial for preventing the shocking event, caused when a blood vessel(血管) in or serving the brain is blocked.

The study looked at the drinking habits of more than 83,000 healthy adults, aged 45 to 74, whose health was tracked for 13 years on average. They found that people who drank at least one cup of coffee a day had about a 20 percent lower risk of stroke, compared to those who rarely drank it. To get an equal effect, about four cups of green tea a day were required.

All results were adjusted to take into account differences between the groups in age composition, gender, smoking, alcohol, weight, diet and exercise. Dr. Yoshihiro Kokubo, lead author of the study, published in the journal Stroke, said, “The regular action of drinking tea and coffee, largely benefits cardiovascular (心脏血管的) health.”

Their results for coffee were similar to that of “study of studies”, presented at a European conference, which found that one to three cups a day was associated with a 14 percent reduction. For three to six cups, there appeared to be a similar but weaker association, but there was no benefit from drinking six or more.

Exactly why coffee and green tea appears to lower stroke risk is unclear, although antioxidants are thought to be at work. However, the science is by no means cut and dried. Caffeine raises blood pressure, and there have been indications that too much coffee can raise stroke risk because of this.

Dr. Dale Webb, from the Stroke Association said, “We welcome this study which suggests that the benefits of antioxidants in coffee and green tea may offset the potential harm from caffeine.” He thought, the results show higher consumption of green tea and coffee might reduce the risks of stroke. “We would like to see further research to understand these findings,” he said.

New discoveries and technological breakthroughs are made every year. Yet, as the information industry moves forward, many people in society are looking back to their roots in terms of the way they eat. A “locavore” movement has emerged in the United States. The movement supports eating foods grown locally and sustainably, rather than prepackaged foods shipped from other parts of the world.

Experts hold that eating local has many merits, and is expected to become a trend featuring sustainability. Erin Barnett is the director of Local Harvest, a company that aims to help connect people to farms in their area. By eating local, she argues, people have a better and more personal understanding of the impact their food consumption has on the rest of the world. “There is a way of connecting the point, where eating locally is an act that raises our awareness of sustainable living,” Barnett says.

The United States’ agricultural output is one of the highest in the world, says Timothy Beach, a professor of geography and geoscience at the University of Texas in Austin, Texas. “There’s just no other place on Earth where the amount of input is so productive,” Beach says of American agriculture. “Nobody can cut off the food we need.”

However, the US food system is not sustainable because of its dependency on fossil(化石) fuels, says Beach. Equipment used on “extremely productive”, farms is quickly consuming Earth’s natural resources, particularly oil. Additionally, the production of agricultural supplements(补充剂), such as fertilizer, uses large amounts of energy.

The world has used close to half of the global oil supply, Beach says, and the second half will be consumed at an even faster rate because of growing population and economic development. Although many businesses are experimenting with wind, solar, and biofuel, Beach says there’s nothing that we see on the horizon that can replace it. “There is no way on Earth we are using fossil fuels sustainably. Then we have to reconsider the impact of eating local,” he says.

A food additive (添加剂) is any substance that is added to food. Many people are put off by the idea of “chemicals in food.” The truth is that all food is made up of chemicals. Natural substances like milk, as well as man-made ones like drinks on sale in the market, can be described by chemical formulas. Some chemical substances are indeed harmful, but a person who refused to consume any chemicals would find nothing to eat.

The things we eat can be divided into natural and man-made substances. Some people feel that only natural foods are healthy and that all man-made ingredients are to be avoided. But many natural chemicals, found in plants and animals, are harmful when eaten, and some laboratory-made substances increase the nutritional value of food. Other chemicals have natural and man-made forms that are exactly alike: vitamin C is vitamin C, whether it comes from a test tube or from an orange. Like “chemical”, “man-made” doesn’t necessarily mean “not fit to eat”.

Food additives are used for many reasons. We add sugar and salt and other things to foods we prepare at home to make them taste better. Food producers have developed a range of additives that stabilize（使稳定）, thicken, harden, keep wet, keep firm, or improve the appearance of their products. Additives can make food more convenient or nutritious, give it a longer shelf life, and make it more attractive to the consumer, thus increasing the sales and profits of the producers.

Food additives are presently the centre of a storm of serious argument. Food producers have been known to use additives that have not been proved safe; some substances in common use have been proved unsafe and have been taken off the market. Many people feel there’s a risk of eating food to which anything has been added. But food additives are now regulated by the FDA of the federal government, and new additives will go through strict testing before they can be placed on the market. For most people, the chances of developing serious side effects (副作用) from the long-term use of presently approved (批准) food additives are very small.