The Nitty-gritty behind How Onions Make You Cry

Adding onions to a recipe can make a meal taste rich and savory, but cutting up the onion can be brutal. Onions release a compound called lachrymatory factor (LF), which makes the eyes sting and water. Scientists know that a certain enzyme causes this irritating compound to form but precisely how it helps LF form in the onion remained an open question. Now, one group reports in ACS Chemical Biology that they have the answer.

According to the National Onion Association, the average American consumes 20 pounds of onions each year. When an onion is cut, it has a natural defense mechanism that springs into action, producing LF. This kind of compound is rare — only four known natural types exist. An enzyme in the onion known as lachrymatory factor synthase (LFS) spurs production of LF in the onion. “Tearless” onions, sold exclusively in Japan for a hefty price, don’t make LFS so they also don’t produce the irritant LF. But scientists have been at a loss to explain exactly how LFS helps LF form. That’s because it is extremely reactive, and LF evaporates or breaks down easily. Marcin Golczak and colleagues wanted to take a different approach to solve this mystery once and for all.

The team determined the crystal structure of LFS and analyzed it. With the crystal structure, they could finally see the architecture of the enzyme as a whole and its active site as it bound to another compound. By combining this information with known information about similar proteins, the group developed a detailed chemical mechanism that could explain the precise steps involved in LF synthesis—and hence, why people wind up crying when they chop an onion.

Source: American Chemical Society

Does Sugar Make You Sad? New Science Suggests So

Anika Knüppel wrote . . . . . . . .

The thought of a cupcake, skillfully frosted with fluffy vanilla icing, may put a smile on your face, but research suggests that, in the long term, a sweet tooth may turn that smile into a frown – but not for the reasons you think. In a new study, published in Scientific Reports, my colleagues and I found a link between a diet high in sugar and common mental disorders.

The World Health Organisation recommends that people reduce their daily intake of added sugars (that is, all sugar, excluding the sugar that is naturally found in fruit, vegetables and milk) to less than 5% of their total energy intake. However, people in the UK consume double – in the US, triple – that amount of sugar. Three-quarters of these added sugars come from sweet food and beverages, such as cakes and soft drinks. The rest come from other processed foods, such as ketchup.

At the same time, one in six people worldwide suffers from a common mental disorder, such as a mood or anxiety disorder. Could there be a link between high sugar consumption and common mental disorders?

Earlier research, published in 2002, examined the link between depression and sugar consumption in six countries. The researchers, from Baylor College in the US, found that higher rates of refined sugar consumption were associated with higher rates of depression.

Since then, a handful of studies have investigated the link between added sugar consumption and subsequent depression. In 2011, researchers in Spain found that when they grouped participants based on their commercial baked food consumption, those who ate the most baked food had a 38% increased chance of developing depression compared with those in the group with the lowest intake. The association remained even after accounting for health consciousness and employment status.

In 2014, researchers studied the association between sweetened beverages in a large US group. They found that sugar-sweetened and artificially sweetened drinks (diet drinks) could increase a person’s risk of developing depression. And, more recently, a 2015 study, including nearly 70,000 women, found higher chances of depression in those with a high added sugar intake, but not in those with a high intake of naturally occurring sugars, such as those found in fruit.

Trying to explain the link

We are still not sure what causes depression, but some researchers believe that biological changes are at the root of it. Some of these changes could be influenced by sugar and sweet taste. For example, a study in rats found that diets high in sugar and fat can reduce a protein called BDNF that influences the growth and development of nerve cells in the brain. This protein is thought to be involved in the development of depression and anxiety.

Another possible biological cause is inflammation. High sugar diets can increase inflammation – a protective reaction of the body, normally directed against microorganisms or foreign substances. While common signs of inflammation, such as redness, are far from a mood disorder, the symptoms that keep us in bed with a cold are much closer, such as low energy and being unable to concentrate. Ongoing research suggests that mood disorders could be linked with inflammation, at least in some cases.

Dopamine is another possible culprit. A study using rats earned headlines for suggesting sweet foods could be as addictive as cocaine. This might be due to affects on dopamine, a brain chemical involved in the reward system. Dopamine is also thought to influence mood. And addiction is itself associated with a higher risk of developing a mood disorder.

Finally, sugar intake could be associated with other factors, such as obesity, which itself is related to mood.

But these associations could also reflect a reverse phenomenon: low mood could make people change their diet. Sweet foods could be used to soothe bad feelings by providing a short-term mood boost. And low mood and anxiety could make simple tasks, such as grocery shopping or cooking, so difficult and exhausting for the sufferer that they might start to avoid them. Instead, they might opt for junk food, takeaways and ready meals – all of which have a high sugar content.

What our study adds to the debate

For our latest study, my colleagues and I put the reverse association idea to the test. We used sugar intake from sweet food and drinks to predict new and recurrent mood disorders in a group of British civil servants. We also investigated whether having a mood disorder would make people more inclined to choose sweet foods and drinks.

We found that men without a mood disorder who consumed over 67g of sugar had a 23% increased risk of suffering from a mood disorder five years later, compared with those who ate less than 40g. This effect was independent of the men’s socioeconomic status, physical activity, drinking, smoking, other eating habits, body fatness and physical health.

We also found that men and women with a mood disorder and a high intake of sugar from sweet food and drinks were at higher risk of becoming depressed again five years later, compared with those who consumed less sugar. But this association was partly explained by their overall diet.

We found no evidence for a potential reverse effect: participants did not change their sugar intake after suffering from mood disorders.

Despite our findings, a number of questions remain about whether sugar makes us sad, whether it affects men more than women, and whether it is sweetness, rather than sugar itself, that explains the observed associations. What is certain, though, is that sugar is associated with a number of health problems, including tooth decay, type 2 diabetes and obesity. So cutting down on sugar is probably a good idea, regardless of whether it causes mood disorders or not.

Source: The Conversation


Today’s Comic

Artificial Sweeteners Linked to Risk of Weight Gain, Heart Disease and other Health Issues

Artificial sweeteners may be associated with long-term weight gain and increased risk of obesity, diabetes, high blood pressure and heart disease, according to a new study published in CMAJ (Canadian Medical Association Journal).

Consumption of artificial sweeteners, such as aspartame, sucralose and stevia, is widespread and increasing. Emerging data indicate that artificial, or nonnutritive, sweeteners may have negative effects on metabolism, gut bacteria and appetite, although the evidence is conflicting.

To better understand whether consuming artificial sweeteners is associated with negative long-term effects on weight and heart disease, researchers from the University of Manitoba’s George & Fay Yee Centre for Healthcare Innovation conducted a systematic review of 37 studies that followed over 400,000 people for an average of 10 years. Only 7 of these studies were randomized controlled trials (the gold standard in clinical research), involving 1003 people followed for 6 months on average.

The trials did not show a consistent effect of artificial sweeteners on weight loss, and the longer observational studies showed a link between consumption of artificial sweeteners and relatively higher risks of weight gain and obesity, high blood pressure, diabetes, heart disease and other health issues.

“Despite the fact that millions of individuals routinely consume artificial sweeteners, relatively few patients have been included in clinical trials of these products,” said author Dr. Ryan Zarychanski, Assistant Professor, Rady Faculty of Health Sciences, University of Manitoba. “We found that data from clinical trials do not clearly support the intended benefits of artificial sweeteners for weight management.”

“Caution is warranted until the long-term health effects of artificial sweeteners are fully characterized,” said lead author Dr. Meghan Azad, Assistant Professor, Rady Faculty of Health Sciences, University of Manitoba. Her team at the Children’s Hospital Research Institute of Manitoba is undertaking a new study to understand how artificial sweetener consumption by pregnant women may influence weight gain, metabolism and gut bacteria in their infants.

“Given the widespread and increasing use of artificial sweeteners, and the current epidemic of obesity and related diseases, more research is needed to determine the long-term risks and benefits of these products,” said Azad.

Source: Science Daily

Manuka Honey: Is It Really A Superfood?

Amanda Barrell wrote . . . . . .

Historical use of honey

Honey has been used to treat wounds since ancient times, as detailed in a document dating back to 1392. It was believed to help in the fight against infection, but the practice fell out of favor with the advent of antibiotics.

As we face the challenge of a growing worldwide resistance to antibiotics, scientists are examining the properties and potential of honey.

Qualities of Manuka honey

The leaves of the Manuka tree, also known as a tea tree, have been known for centuries among the indigenous tribes of New Zealand and southern Australia for their healing powers.

Bees that collect nectar from this tree make Manuka honey, which harbors some of healing properties.

All honey contains antimicrobial properties, but Manuka honey also contains non-hydrogen peroxide, which gives it an even greater antibacterial power.

Some studies have found Manuka honey can also help to boost production of the growth factors white blood cells need to fight infection and to heal tissue.

Manuka honey contains a number of natural chemicals that make it different:

  • Methylglyoxal (MGO): This has been shown to be effective against several bacteria, including Proteumirabilis and Enterobacter cloacae.
  • Dihydroxyacetone (DHA): This is found in the nectar of Manuka flowers and converts into MGO during the honey production process.
  • Leptosperin: This is a naturally occurring chemical found in the nectar of Manuka plants and a few close relatives.

Manuka honey and wound care

Medical grade honey, used by healthcare professionals as part of a wound dressing, can help some kinds of wounds to heal.

Experts believe that because Manuka honey has added antibacterial and healing properties, it may be even more effective. At the moment, however, there is little evidence to support the theory.

A Cochrane Review looked at all the evidence available to support the use of honey in wound care. Published in 2015, the study said the differences in wound types made it impossible to draw overall conclusions about the effects of honey on healing.

The study found strong evidence that honey heals partial thickness burns around 4 to 5 days more quickly than conventional dressings. There is also evidence indicating that honey is more effective than antiseptic and gauze for healing infected surgical wounds.

Another study concluded that honey has rapid diabetic wound healing properties, but recommended more research to confirm that honey can be used as a first line of treatment for these types of wounds.

While some research does show that honey can help improve certain conditions, more studies are needed to confirm honey’s benefits for:

  • mixed acute and chronic wounds
  • pressure ulcers
  • Fournier’s gangrene
  • venous leg ulcers
  • minor acute wounds
  • Leishmaniasis

Manuka honey and bacteria

Antibiotics are used to prevent and treat bacterial infections all over the world. However, the bacteria the drugs are deployed to kill can adapt and become resistant.

Manuka honey has antibacterial properties, and may be able to fight superbugs resistant to most standard antibiotics.

This resistance is currently happening all over the world, and a growing number of infections are becoming harder to treat. This leads to longer hospital stays, higher medical costs, and ultimately, more deaths.

The World Health Organization (WHO) has listed resistance to antibiotics as the one of the biggest threats to global health, food security, and development.

The natural antibacterial properties of honey may be useful in this fight. In the lab, Manuka honey has been shown to be able to inhibit around 60 species of bacteria. These include Escherichia coli (E. coli) and salmonella.

Some studies have shown that Manuka honey can fight so-called superbugs that have become resistant to antibiotics. These include staphylococcus aureus (MRSA-15) and pseudomonas aeruginosa.

This line of investigation is still in its infancy. These have been small, lab-based tests which combined medical grade Manuka honey with antibiotics.

There is still a lot of work to be done before scientists can come to a conclusion.

Other health benefits

There are many other potential health benefits of Manuka honey. These include:

  • reducing high cholesterol
  • reducing inflammation
  • reducing acid reflux
  • treating acne

There is, however, limited evidence for its use in these areas.

Using Manuka honey

The medical grade honey used to dress wounds is very different from the honey sold in stores.

Medical grade honey is sterilized, with all impurities removed, and prepared as a dressing. Wounds and infections should always be seen and treated by a healthcare professional.

Store-bought Manuka honey can be used in the same manner as any other honey: on toast, on porridge, or to sweeten drinks.

There is no clear evidence that people who consume Manuka honey in this way will notice any benefit to their health. It is not clear how the active ingredients that provide Manuka honey with its healing properties survive in the gut.

Risks

Honey is usually around 80 percent sugar, mainly supplied by glucose, fructose, and sucrose, so moderate intake is recommended. This is particularly true if you have diabetes.

Due to the recent trend for Manuka honey, it can be expensive, so it is important to make sure you know what you are looking for.

When buying Manuka honey from the store, look for the Unique Manuka Factor (UMF) mark. This means the honey has been produced by one of the 100+ beekeepers, producers, and exporters licenced by the UMF Honey Association.

The number displayed next to the UMF mark represents the quantity of Manuka key markers, leptosperin, DHA and MGO. Consumers are advised to choose UMF 10+ and above.

Source: Medical News Today

Video: Why Olive Oil is Awesome

Whether you sop it up with bread or use it to boost your cooking, olive oil is awesome.

But a lot of chemistry goes on in that bottle that can make or break a product. Take the “extra virgin” standard: Chemistry tells us that a higher free-fatty-acid content leads to a lower grade, less tasty oil. And those peppery notes are thanks to antioxidants that contribute to olive oil’s healthy reputation.

Check out the video for more olive oil chemistry, including how to keep yours fresh and how to best use it to give your food a flavor boost.

Watch video at You Tube (4:50 minutes) . . . . .