DRINKING BEET ROOT JUICE BEFORE EXERCISE BENEFITS HEART PATIENTS

A small yet significant study shows that beetroot juice improves exercise function in chronic obstructive pulmonary disease (COPD) patients.

The new research by Wake Forest University looked at a small group of COPD patients who drank beetroot juice as compared to a placebo drink before exercise.

“The intent of this study was to determine if acute ingestion of beetroot juice, which is rich with nitrates, prior to exercising could improve the exercise capacity of COPD patients,” said Michael Berry, chair of Wake Forest’s department of health and exercise science.

COPD makes it difficult for patients to breathe and worsens over time.

In turn, they tend to limit their activities, become more sedentary, and lose fitness and physical function.

The findings showed overall that those patients who drank beetroot juice were able to extend their exercise time and had reduced exercise diastolic and resting systolic blood pressures.

“This is the first study to demonstrate beneficial effects of dietary nitrite supplementation on exercise performance and blood pressure in patients with COPD,” he added. One of the benefits of exercise is that if you get positive results, you are more likely to continue doing it.

“If beetroot juice positively impacts those results, it could motivate COPD patients to continue to be physically active and improve their health,” he added.

The research appeared in the journal Nitric Oxide: Biology and Chemistry.

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GRAPEFRUIT JUICE STEMS WEIGHT GAIN IN MICE FED A HIGH FAT DIET

Fad diets come and go, but might there be something to the ones that involve consuming grapefruit and grapefruit juice? New research at the University of California, Berkeley, suggests that a closer look at grapefruit juice is warranted.

A new study, to be published in the peer-reviewed journal PLOS ONE, found that mice fed a high-fat diet gained 18 percent less weight when they drank clarified, no-pulp grapefruit juice compared with a control group of mice that drank water. Juice-drinking mice also showed improved levels of glucose, insulin and a type of fat called triacylglycerol compared with their water-drinking counterparts.

If these findings sound somewhat familiar, it may be because the link between grapefruit juice and weight loss -- or just decreased weight gain -- has been touted in Hollywood diets before. However, the earlier studies behind those claims were often small, not well-controlled and contradictory, according to Andreas Stahl and Joseph Napoli, the two UC Berkeley faculty members who led the new research.

This latest work was funded by the California Grapefruit Growers Cooperative, but the UC Berkeley researchers emphasized that the funders had no control or influence over the study design or research findings. Both Stahl and Napoli said they went into this research with some skepticism.

"I was surprised by the findings," said Stahl, associate professor of nutritional sciences and toxicology. "We even re-checked the calibration of our glucose sensors, and we got the same results over and over again."

Napolli added that "we see all sorts of scams about nutrition. But these results, based on controlled experiments, warrant further study of the potential health-promoting properties of grapefruit juice."

Pitting juice against water

The study authors randomly divided mice into six groups, including a control group that drank only water. Those drinking grapefruit juice got a mixture diluted with water at different concentrations, and sweetened slightly with saccharin to counteract grapefruit's bitterness. The researchers also added glucose and artificial sweeteners to the control group's water so that it would match the calorie and saccharin content of the grapefruit juice.

At the end of the study period, the mice that ate the high-fat diet and drank diluted grapefruit juice not only gained less weight than their control counterparts, they also had a 13 to 17 percent decrease in blood glucose levels and a threefold decrease in insulin levels, which reveals greater sensitivity to insulin. (In Type 2 diabetes, the pancreas makes extra insulin to compensate for increased resistance to the hormone.)

The researchers gave one group of mice naringin, a bioactive compound in grapefruit juice that has been identified as a key agent in weight loss, and another group metformin, a glucose-lowering drug often prescribed for those with Type 2 diabetes.

The mice were fed a diet that was either 60 percent fat or 10 percent fat for 100 days, and their metabolic health was monitored throughout the study.

"The grapefruit juice lowered blood glucose to the same degree as metformin," said Napoli, professor and chair of nutritional sciences and toxicology. "That means a natural fruit drink lowered glucose levels as effectively as a prescription drug."

Weight effects only seen in high-fat diet

The group of high-fat-diet mice that received naringin had lower blood glucose levels than the control group, but there was no effect on weight, suggesting that some other ingredient in grapefruit juice is also beneficial.

"There are many active compounds in grapefruit juice, and we don't always understand how all those compounds work," said Stahl.

The study did not find as big an impact on mice that ate a low-fat diet. Those that drank the grapefruit juice saw a two-fold decrease in insulin levels, but there was no significant change in weight or other metabolic variables.

"The effects were more subtle for the low-fat diet group," explained Stahl. "Mice are incredibly healthy animals with naturally low levels of bad cholesterol. So if they are eating a healthy, low-fat diet, it will take more to see a significant effect on their health."

The researchers said they ruled out the typical explanations for weight loss in their study. It wasn't the amount of food consumed, since the ingested calories among the different groups were about the same. The level of activity and body temperatures were comparable, and the authors even checked the calories eliminated in the feces of the mice to check for problems with the body's absorption of nutrients.

"Basically, we couldn't see a smoking gun that could explain why or how grapefruit juice affects weight gain," said Stahl.

The researchers said they hope to continue the investigation into grapefruit juice. "Obesity and insulin resistance are such huge problems in our society, " said Stahl. "These data provide impetus to carry out more studies."

ANTIOXIDANT CAPACITY OF ORANGE JUICE MULTIPLIED TENFOLD

The antioxidant activity of citrus juices and other foods is undervalued. A new technique developed by researchers from the University of Granada for measuring this property generates values that are ten times higher than those indicated by current analysis methods. The results suggest that tables on the antioxidant capacities of food products that dieticians and health authorities use must be revised

Orange juice and juices from other citrus fruits are considered healthy due to their high content of antioxidants, which help to reduce harmful free radicals in our body, but a new investigation shows that their benefits are greater than previously thought.

In order to study these compounds in the laboratory, techniques that simulate the digestion of food in the digestive tract are used, which analyse only the antioxidant capacities of those substances that can potentially be absorbed in the small intestine: the liquid fraction of what we eat.

"The problem is that the antioxidant activity of the solid fraction (the fibre) isn't measured, as it's assumed that it isn't beneficial. However, this insoluble fraction arrives at the large intestine and the intestinal microbiota can also ferment it and extract even more antioxidant substances, which we can assess with our new methodology," José Ángel Rufián Henares, professor at the University of Granada, explains.

His team has developed a technique called 'global antioxidant response' (GAR), which includes an in vitro simulation of the gastrointestinal digestion that occurs in our body, whilst taking into account the 'forgotten' antioxidant capacity of the solid fraction.

The method, the details of which are published in the journal 'Food Chemistry', includes assessments of various physical and chemical parameters, such as colour, fluorescence and the relationship between the concentrations analysed and compounds indicators such as furfural.

Upon applying the technique to commercial and natural orange, mandarin, lemon and grapefruit juices, it has been proved that their values greatly increase. For example, in the case of orange juice, the value ranges from 2.3 mmol Trolox/L (units for the antioxidant capacity) registered with a traditional technique to 23 mmol Trolox/L with the new GAR method.

"The antioxidant activity is, on average, ten times higher than that which everyone thought up until now, and not just in juices, but also in any other kind of food analysed with this methodology," highlights Rufián Henares, who notes its possible application: "This technique and the results derived from it could allow dieticians and health authorities to better establish the values of the antioxidant capacity of foods."

With the help of this method, scientists have also created a mathematical model in order to classify juices according to their natural and storage conditions, which ensures that the correct raw materials and sterilisation and pasteurisation processes are used.