Fruit And Vegetable News: Can An Orange A Day Keeps Macular Degeneration Away?

A new study has shown that people who regularly eat oranges are less likely to develop macular degeneration than people who do not eat oranges. Researchers at the Westmead Institute for Medical Research interviewed more than 2,000 Australian adults aged over 50 and followed them over a 15-year period. The research showed that people who ate at least one serving of oranges every day had more than a 60 percent reduced risk of developing late macular degeneration 15 years later.

Lead Researcher Associate Professor Bamini Gopinath from the University of Sydney said the data showed that flavonoids in oranges appear to help prevent against the eye disease. "Essentially we found that people who eat at least one serving of orange every day have a reduced risk of developing macular degeneration compared with people who never eat oranges," Gopinath says. "Even eating an orange once a week seems to offer significant benefits. The data shows that flavonoids found in oranges appear to help protect against the disease."

Gopinath said that until now most research has focused on the effects of common nutrients such as vitamins C, E and A on the eyes. "Our research is different because we focused on the relationship between flavonoids and macular degeneration,” she continued. "Flavonoids are powerful antioxidants found in almost all fruits and vegetables, and they have important anti-inflammatory benefits for the immune system. We examined common foods that contain flavonoids such as tea, apples, red wine and oranges. Significantly, the data did not show a relationship between other food sources protecting the eyes against the disease."

One in seven Australians over 50 have some signs of macular degeneration. Age is the strongest known risk factor and the disease is more likely to occur after the age of 50. There is currently no cure for the disease. The research compiled data from the Blue Mountains Eye Study, a benchmark population-based study that started in 1992. It is one of the world's largest epidemiology studies, measuring diet and lifestyle factors against health outcomes and a range of chronic diseases. "Our research aims to understand why eye diseases occur, as well as the genetic and environmental conditions that may threaten vision,"  Gopinath concluded.

Sweet Potato Pairings

The relationship between sweet potato crops and soil nitrogen can be complicated. Too little nitrogen and sweet potato plants don’t grow well and have low yields. Too much nitrogen, however, boosts the growth of leaves and branches at the expense of storage roots. That also leads to low yields. “Carefully managing soil nitrogen levels is essential to obtain high yields from sweet potato crops,” says Adalton Fernandes, an agronomist at the Center for Tropical Roots and Starches at São Paulo State University in Brazil.

Fernandes is the lead author of a recent study that determined how much nitrogen is needed to maximize yields from sweet potato crops in Brazil. The researchers discovered field history matters when trying to apply the optimal amount of nitrogen for sweet potato crops. Cover crops grown in the same plots prior to sweet potato crops affected how much nitrogen was needed. Sweet potato plants grown in plots previously used to grow legume cover crops needed 35 percent less nitrogen fertilizer. Growing sweet potatoes after a cereal cover crop, however, was no different than growing them in a plot that had previously just had weeds. “We show that growing legume cover crops, and incorporating them into the soil as they flower, is a simple technique that can reduce how much mineral nitrogen needs to be applied for sweet potato farming,” says Fernandes.

Cover crops are often grown cyclically with economic or cash crops. They may be incorporated into the soil as green manure. They may also be left on the surface as living mulches. Different cover crops bring different benefits to the growing relationship. Legumes, for example, can increase soil nitrogen levels. Beneficial bacteria in their root nodules pull atmospheric nitrogen into the soil. But they also decompose faster than cereal cover crops once terminated. “That releases nitrogen into the soil earlier during the sweet potato growth cycle,” says Fernandes. “We needed to know more about how different cover crops affect soil nitrogen availability for subsequent sweet potato crops.”

Fernandes and colleagues used a study site in southeastern Brazil. The site is a good match for the tropical conditions and sandy soil typical of several areas where sweet potato is grown in Brazil. In different plots, the researchers grew either one of two legume crops, a cereal crop, or allowed weeds to grow from seeds already present in the soil. When the legume and cereal cover crops were flowering, they were terminated. The plants were incorporated into the soil. Subsequently, the researchers planted sweet potato in the plots. They tested how much nitrogen was needed to maximize yields.

Understanding Nitrogen

When sweet potato was grown after legume cover crops, they needed about 110 pounds of nitrogen per hectare - roughly the size of a baseball field - for optimal yields. In contrast, sweet potato crops needed more than 168 pounds per hectare of nitrogen when grown after a cereal cover crop or after weeds. “We show that there is no reason to use a cereal cover crop prior to sweet potato cultivation,” says Fernandes.

Currently, recommendations of how much nitrogen fertilizer to use with sweet potato crops do not consider the history of cultivation in the area. That can result in farmers using more or less fertilizer than needed. “We now better understand how much nitrogen is needed to maximize sweet potato yields in tropical regions,” says Fernandes. “This will help manage the application of mineral nitrogen fertilizers during sweet potato cultivation.” In addition to maximizing yields, using less fertilizer also reduces costs for farmers. That’s especially important in Brazil. Much of the sweet potato crop is grown on family farms with low technology use.

Fernandes is now pairing other species of legumes as cover crops. He is testing whether they may be more efficient at providing nitrogen for sweet potato crops. He is also exploring whether combining legumes and cereals as cover crops in the same area can provide different benefits to sweet potato farmers.

Apples And Tomatoes May Help Repair Lungs Of Ex-Smokers

A study from the Johns Hopkins Bloomberg School of Public Health found the natural decline in lung function over a 10-year period was slower among former smokers with a diet high in tomatoes and fruits. This was especially true of apples, suggesting certain components in these foods might help restore lung damage caused by smoking. The researchers found that adults who on average ate more than two tomatoes or more than three portions of fresh fruit a day had a slower decline in lung function compared to those who ate less than one tomato or less than one portion of fruit a day, respectively. The researchers inquired about other dietary sources such as dishes and processed foods containing fruits and vegetables – such as tomato sauce - but the protective effect was only observed in fresh fruit and vegetables.

The paper, which is part of the Ageing Lungs in European Cohorts (ALEC) Study, funded by the European Commission and led by Imperial College London, also found a slower decline in lung function among all adults, including those who had never or had stopped smoking, with the highest tomato consumption. Poor lung function has been linked with mortality risks from all diseases, including chronic obstructive pulmonary disease (COPD), heart disease, and lung cancer.

“This study shows that diet might help repair lung damage in people who have stopped smoking,” says Vanessa Garcia-Larsen, assistant professor in the Bloomberg School’s Department of International Health and the study’s lead author. “It also suggests that a diet rich in fruits can slow down the lung’s natural aging process even if you have never smoked. The findings support the need for dietary recommendations, especially for people at risk of developing respiratory diseases such as COPD.”

For the study, the research team assessed diet and lung function of more than 650 adults in 2002, and then repeated lung function tests on the same group of participants 10 years later. Participants from three European countries - Germany, Norway and the United Kingdom - completed questionnaires assessing their diets and overall nutritional intake. They also underwent spirometry, a procedure that measures the capacity of lungs to take in oxygen. The test collects two standard measurements of lung function: Forced Exhaled Volume in 1 second (FEV1), which measures how much air a person can expel from their lungs in one second; and Forced Vital Capacity (FVC), the total amount of air a person can inhale in six seconds. The study controlled for factors such as age, height, sex, body mass index - an indicator of obesity - socio-economic status, physical activity and total energy intake.

Among former smokers, the diet-lung-function connection was even more striking. Ex-smokers who ate a diet high in tomatoes and fruits had around 80 milliliters slower decline over the 10-year period. This suggests that nutrients in their diets are helping to repair damage done by smoking. ”Lung function starts to decline at around age 30 at variable speed depending on the general and specific health of individuals,” says Garcia-Larsen “Our study suggests that eating more fruits on a regular basis can help attenuate the decline as people age, and might even help repair damage caused by smoking. Diet could become one way of combating rising diagnosis of COPD around the world.”

Why Do Onions Make You Cry?

Approximately 170 countries grow onions, and it’s estimated that 9.2 million acres of onions are harvested annually around the world, according to the National Onion Association  Onions are low in calories and packed with vitamins, minerals and antioxidants. They also go great in salads, omelets and guacamole recipes. However, as everyone from expert chefs to culinary novices has learned, onions can bring a tear to your eye, and an expert from the Texas A&M College of Medicine explains why that happens.

Onions are vegetables that grow underground, and beneath the surface are a lot of critters who are trying to grab a bite to eat, but onions have a way to protect themselves. Sulfur in the dirt mixes with the growing onion and creates amino acid sulfoxides, which are sulfur compounds that readily turn into a gas. When an onion breaks apart, the sulfoxides and onion enzymes are released, and this creates sulfenic acid. The sulfenic acid and onion enzymes react and create a gas called syn-propanethial-S-oxide.

This gas floats up from the chopped or bitten onion and deters critters - and causes humans to shed tears. It takes a lot of precise chemical reactions, and some vegetables related to onions will produce fewer tears. White, yellow and red onions all have higher concentration of the onion enzyme necessary to create syn-propanethial-S-oxide while sweet onions, green onions and scallions have fewer of the necessary enzymes. “It really is a complicated chemical process that creates the gas,” said Robert H. Rosa Jr., MD, ophthalmologist and professor of surgery and medical physiology at the Texas A&M College of Medicine. “They all act as precursors that create the lachrymatory process or what makes you tear up.”

Avoiding The Tears

Your eyes are sensitive, and considering their responsibilities, it’s good that they have defenses to harmful gases. “Your eyes have a set of nerves that detect anything that’s potentially harmful to your eyes,” Rosa said. “Your eyes react to the gas that is formed, and your eyes try to flush it out with tears. Luckily, the gases that are produced from chopping onions are more nuisance than harm. Chopping onions can cause some burning and irritation and tears. Other than that, it’s pretty safe on your eyes. It’s a temporary sensation with no known long-term effects and won’t worsen any other conditions like pink eye.”

Some people may have more sensitive eyes than others, which is why not everyone will tear up when they chop onions but why others may feel the effects on the other side of the room. There are a few different ways to avoid tears when you’re cutting onions. You can prevent the gas from reaching your eyes by wearing protective goggles, but that may be a bit excessive considering you’re in a kitchen and not a laboratory. “Some people may cut the onions in a bowl of water,” Rosa said. “I’d personally recommend using eye drops, like comfort drops, to help lubricate or rinse the eyes and dilute the gas exposure to the eyes.”

There has been talk about genetically modifying onions to knock out the alliinase enzyme that causes tears, without changing the particular spice that onions provide in flavor. However, tear-free onions have yet to be commercialized.


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