The benefits of red onions

During the current doom and gloom we need to be cheered up with some positive news. And should you read this when a vaccine has disarmed the coronavirus causing the COVID-19 pandemic in 2020 and governments around the world have taken the necessary actions to limit global warming to 1.5ºC, well, you might still appreciate some good news. 

So here goes.

Multiple health benefits

The next time you go shopping you might reach for red onions. Onions belong to the Allium family of plants, which also includes chives, garlic, and leeks. Farmers have cultivated Allium vegetables for millennia. These vegetables have characteristic pungent flavours and some beneficial medicinal properties. The benefits among many include a reduction of the risk of several types of cancer, improving mood, and maintaining skin and hair health.

Looking back in time, ancient medical texts from Egypt, Greece, Rome, China, and India all cite therapeutic applications for Allium vegetables.

Contemporary studies confirm the early findings. One review from 2015 found a general relationship between an increased consumption of Allium vegetables and a reduced risk of cancer, especially cancers of the stomach and gastrointestinal tract.

Such a relationship was further supported by a 2019 Chinese study that compared 833 people with colorectal cancer with 833 people who did not have the disease. The researchers found that the risk of colorectal cancer was 79% lower in those who regularly consumed Allium vegetables, such as onions.

Experts do not fully understand the exact mechanism by which some compounds in onions inhibit cancer. There are compounds called organosulfurs in onions, some of which have been shown to suppress aspects of tumour growth. However, further research is necessary to confirm which compounds in onion have protective effects against cancer.

But there is more

A wide range of further beneficial effects have also been proven. Different biological properties, such as antioxidant, antimicrobial and anti-diabetic activities, have been reported.

Not surprising as onions are nutrient-dense. One medium onion has just 44 calories but delivers a considerable dose of vitamins, minerals and fibre.

As a good source of vitamin C, onions may support the building and maintenance of collagen. Collagen provides structure to skin and hair.

A 2014 review found that among various activities of Allium vegetables, regulation of hypoglycaemic activity is considered important in helping to control diabetes. Sulfur compounds including S-methylcysteine and flavonoids such as quercetin are mainly responsible for the hypoglycaemic activity. S-methylcysteine and flavonoids help to decrease the levels of blood glucose, serum lipids, oxidative stress and lipid peroxidation, as well as increasing antioxidant enzyme activity and insulin secretion. 

2019 review found that quercetin, a compound in onion skin, had links to lower blood pressure when the researchers extracted it and administered it as a supplement.

Somewhat surprisingly onions have been shown to be able to fight potentially dangerous bacteria, such as Escherichia coliPseudomonas aeruginosaStaphylococcus aureus and Bacillus cereus.

Onions are also rich in B vitamins, including folate (B9) and pyridoxine (B6) playing key roles in metabolism, red blood cell production and nerve function.

Lastly, they’re a good source of potassium, a mineral in which many people are lacking.

I hope you’re convinced by now.

So why red onions?

Any Allium vegetable would do but there is something special with the red colour of red onions.

A Canadian study revealed that the red onion not only has high levels of quercetin, but also high amounts of anthocyanin, which enriches the scavenging properties of quercetin molecules. Anthocyanin is instrumental in providing colour to fruits and vegetables so it makes sense that the red onions, which are darkest in colour, would have the most cancer-fighting power.

There are plenty more benefits associated with Allium vegetables, but this is it for now as I’m off to buy some red onions.

Mycotoxins in a Changing Climate

Global climate change is an issue we should take very seriously now or it will threaten our future food supply. However, I am writing this in June 2020 in the middle of the coronavirus pandemic that is attracting all the attention. There are so far more than 6 million people affected worldwide and soon more than 400,000 deaths.

Most countries, but not all, have reacted with urgency to the acute situation with people movements severely restricted and huge amounts of money spent to support economies. More than one hundred attempts to develop vaccines agains the COVID-19 disease are under way to prevent future outbreaks.

Willingness to limit climate change lacking

We already have the “vaccines” or knowhow to prevent further escalation of the changing climate. Although climate change in the longer term will threaten food security, that is global access to food, and negatively impact food safety with the potential to cause much more pain and suffering, hunger and deaths, it is not getting the same attention as a novel acute disease.

There are many pathways through which climate related factors may impact food safety including: changes in temperature and precipitation patterns, increased frequency and intensity of extreme weather events, ocean warming, and changes in the transport pathways of complex contaminants.

Food security might be the more serious challenge as sufficient access to nutritious food is already an issue in many parts of the world, but long-term quality of life is also threatened by food contamination. We have already covered accumulation of arsenic as an example of heavy metal increases in food caused by climate change. Here we will cover aflatoxin as an example of an increased threat from a range of mycotoxins as fungal growth is influenced by climate change.

Mycotoxin threat will increase

Mycotoxins are compounds naturally produced by a large variety of fungi (moulds) that can cause acute effects, including death, along with chronic illnesses from long-term exposure, including various forms of cancer. It has been estimated that 25% of the world’s yearly crop production is already contaminated with mycotoxins. Mycotoxins are known to occur more frequently in areas with a hot and humid climate.

Aflatoxins, which have the highest acute and chronic toxicity of all mycotoxins, assume particular importance. Aflatoxin produced by Aspergillus flavus and A. parasiticus is a genotoxic carcinogen, but is also a potent acute toxin, and is widely distributed associated especially with maize, groundnuts, tree nuts, figs, dates and certain oil seeds such as cottonseed.

Aflatoxins are a group of approximately 20 related fungal metabolites. They are heat stable and difficult to destroy during processing. Thus exposure, both acute and chronic, can have significant impacts on vulnerable groups, especially babies and children. Four aflatoxins – B1, B2, G1 and G2 – are particularly dangerous to humans and animals.

Health effects of aflatoxin exposure

Outbreaks of acute aflatoxicosis were reported in Kenya in 2004 with 125 deaths resulting from consumption of aflatoxin contaminated maize with repeated events in 2005 and 2006. Most recently several deaths attributed to aflatoxins were reported during the summer of 2016 in the United Republic of Tanzania.

However, chronic effects are much more common. Hepatocellular carcinoma, or liver cancer, is the third leading cause of cancer deaths worldwide, with prevalence 16-32 times higher in developing countries than in developed countries. Of the 550,000-600,000 new cases worldwide each year, about 25,000-155,000 may be attributable to aflatoxin exposure. Most cases occur in sub-Saharan Africa, Southeast Asia, and China with largely uncontrolled aflatoxin exposure in food.

The geographical areas subject to aflatoxin growth in maize and wheat are expected to change with temperature increases – it is predicted that aflatoxin contamination and the associated food safety issues will become prevalent in Europe with a temperature increase of +2°C.

Changes in contamination patterns

Aflatoxin contamination causes significant loss for farmers, businesses, and consumers of varied susceptible crops. Climate change alters the complex communities of aflatoxin-producing fungi. This includes changes in space, time and in the quantity of aflatoxin-producers. Generally, if the temperature increases in cool or temperate climates, the respective countries may become more susceptible to aflatoxins. However, tropical countries may become too inhospitable for conventional fungal growth and mycotoxin production.

Although some regions can afford to control the environment of storage facilities to minimize post-harvest problems, this happens at high additional cost.

Many industries frequently affected by aflatoxin contamination know from experience and anecdote that fluctuations in climate impact the extent of contamination. Climate influences contamination, in part, by direct effects on the causative fungi. As climate shifts, so do the complex communities of aflatoxin-producing fungi. This includes changes in the quantity of aflatoxin-producers in the environment and alterations to fungal community structure.

Fluctuations in climate also influence predisposition of hosts to contamination by altering crop development and by affecting insects that create wounds on which aflatoxin-producers proliferate. Aflatoxin contamination is prevalent both in warm humid climates and in irrigated hot deserts. In temperate regions, contamination may be severe during drought.

Public health threat

As usual prevention is much better than late action to repair already existing damage. This is especially important in at risk regions such as parts of Africa and Asia where the risks of exposure to mycotoxins may increase under predicted climate change conditions.

The combination of future food scarcity and contamination of a larger part of the food supply has the potential of creating an explosive public health threat.