Hangry? The Science behind hunger, anger and low glucose levels

Have you ever been irritable, annoyed or negative only to realize that you are hungry? If so, you’ve experienced “hangry” (an amalgam of hungry and angry) – an episode in which some people get short-tempered and grumpy when they have gone too long without eating.

But where does hanger come from? The answer lies in processes that occur in the body when it needs food. When food is consumed, the carbohydrates, proteins and fats are digested into simple sugars (glucose), amino acids and free fatty acids. These nutrients are then delivered from the bloodstream to organs and tissues. As time passes after your last meal, the amount of nutrients circulating in the bloodstream begins to decline. If blood glucose levels drop to a certain threshold, your brain will perceive it as a life-threatening situation. Unlike most other organs and tissues, your brain is critically dependent on glucose to do its work. Lower blood glucose levels can make it harder to concentrate and perform simple tasks. It can also make it more difficult to behave within socially acceptable norms.

New research published in the Journal of Pharmacology found that “hanger” is real.  The study examined whether chronic, long-term hypoglycemia – low blood sugar – is a risk factor for developing depression-like behaviours. “Evidence revealed that a change in glucose level can have a lasting effect on mood,” said Francesco Leri, professor and chair of the department of psychology at the University of Guelph. Leri and his team administered a compound to the rats that temporarily blocked their cells from absorbing glucose.  They were then placed in a specific chamber. On a separate occasion, the rats were injected water and placed in a different chamber. The rats seemed more sluggish when given the glucose blocker. Also, when given the choice of which chamber to re-enter, the majority of rats actively avoided the chamber where they experienced hypoglycemia. “This type of avoidance behaviour is an expression of stress and anxiety,” Leri stated. The researchers tested blood levels of the rats after they experienced hypoglycemia and found more corticosterone, an indicator of physiological stress.

“When people think about depressed mood states and stress, they think about the psychological factors, not necessarily the metabolic factors. But we found eating habits can have an impact,” said lead researcher Thomas Horman from the University of Guelph.

The next time you feel impatient or agitated ask yourself when you last ate. Here are a few ways to ward off “hanger”:

Eat something before you become too hungry;

Create a consistent eating schedule;

Plan ahead. Carry healthy snacks, eat a protein-rich breakfast or lunch to give you lasting energy;

Give it a time-out. Deal with more challenging situations after food, not before.

High levels of carbon dioxide could be making rice less nutritious

Rice is the culinary foundation for much of the world and provides 25 percent of the total calories consumed globally. According to research in Science Advances Critical, nutrients found in rice which include protein, B vitamins, iron and zinc are poised to decline. “It is the primary food available for the poorest people in the world, particularly for those in Asia,” said Lewis Ziska, co-author of the new study.

Ziska and his colleagues studied 18 rice strains grown around the world using a technique called Free-Air Carbon dioxide Enrichment (FACE). The rice was grown at sites in China and Japan using an open-field method within standard rice fields. Plants were subjected to atmospheric carbon dioxide concentrations of 568 to 590 parts per million. Current concentrations are 410 parts per million – and growing each year at about 2 parts per million.

After harvesting the rice, researchers found an average of 10.3 percent reduction in protein across all the tested varieties and one cultivar showed a 20 percent drop in protein. Iron content fell an average of 8 percent, while the average decline in zinc was 5.1 percent, with some strains experiencing a 15 percent fall. Vitamin B1, B2, B5 and B9 concentrations also fell as CO2 levels rose.  

The research aligns with a common theme in climate findings, which is that poor and marginalized communities around the world would be most affected by the reduction of nutrients. It also shows that these individuals would find it difficult to adjust and diversify their diets to obtain nutrients that they would be lacking. Approximately 600 million people in countries including Bangladesh, Cambodia and Indonesia get more than half of their daily calories and protein directly from rice.

The finding has serious public health implications, especially as CO2 emissions are projected to increase in the coming decades. This may push the international community to adopt more effective initiatives to lower our global production of CO2.

However, not all varieties of rice responded the same way. Future research may examine the possibility of finding varieties of rice that can remain nutritious despite the change in the atmosphere – a project that is critical to maintaining standards of global public health.

MIND diet could reduce cognitive decline in stroke survivors

The MIND diet (short for Mediterranean-DASH Diet Intervention for Neurodegenerative Delay) is a hybrid of the Mediterranean and DASH (Dietary Approaches to Stop Hypertension) diets. Both diets have been found to reduce the risk of cardiovascular conditions such as heart attack, hypertension and stroke. Researchers at Rush University Medical Center created the diet, and according to preliminary findings, the diet may help slow the cognitive decline in stroke survivors. The discovery is significant since stroke survivors are twice as likely to develop dementia when compared to the general population.

“The foods that promote brain health, including vegetables, berries, fish and olive oil, are included in the MIND diet,” said Dr. Laurel J. Cherian, a vascular neurologist and the lead author of the study. The MIND diet has 15 dietary elements, including ten brain-healthy food groups, and five unhealthy groups which include red meat, butter, cheese, pastries and sweets, and fried and fast food.

From 2004 to 2017, Cherian and colleagues studied 106 participants for the Rush Memory and Aging Project who had a history of stroke associated with a decline in their ability to think, reason and remember. Participants were assessed every year for an average of 5.9 years, and their eating habits were monitored using food journals.

The researchers grouped participants into three groups: (1) those who were highly adherent to the MIND diet; (2) those who were moderately adherent; and (3) those who were least adherent. Participants whose diets scored highest on the MIND diet grading scheme had substantially slower rates of cognitive decline than those who scored lowest. “The Mediterranean and DASH diets have been shown to be protective against coronary artery disease and stroke, but it seems that the nutrients emphasized in the MIND diet may be better suited to overall brain health and preserving cognition,” Cherian said. According to Cherian, studies have found that folate, vitamin E, omega-3 fatty acids, carotenoids and flavonoids are associated with slower rates of cognitive decline, while substances such as saturated and hydrogenated fats have been linked with dementia.

To adhere to the MIND diet, you need to eat at least three servings of whole grains and two portions of vegetables every day, one of which must be a leafy green; you must also snack most days on nuts, have beans every other day, eat poultry and berries at least twice a week and eat fish once a week.

Cherian cautions that the study had a relatively small number of participants and its findings cannot be interpreted as a cause-and-effect relationship. Although further research is needed to understand the link between this style of eating and its positive effects on the brain, “For now, I think there is enough information to encourage stroke patients to view food as an important tool to optimize their brain health,” says Cherian.