An article originally published in The conversation. It was written by María Asunción Martínez Brocca, Full Professor of the Department of Medicine, Faculty of Medicine. Head of the Endocrinology and Nutrition Service, Virgen Macarena University Hospital, University of Seville.
Among the protagonists of this food enigma that encourages you to open the fridge again and again, is the orexins A and B, or hypocretins: two small molecules produced by certain nerve cells (neurons) in the hypothalamus. This important region of our brain is involved in the regulation of the autonomic nervous system and many functions such as reproduction, thermoregulation or even hunger.
Although their functions were initially related to food regulation, particularly appetite stimulation, they are now known to contribute to many other effects all over our body.
They influence, for example, sleep regulation, cardiovascular and endocrine functions, regulation of energy expenditure and thermogenesis, reward systems and mood. They also modulate many behaviors related to our mental and physical health, ranging from arousal to emotional swings to our sensitivity to pain. They are still players in diseases as diverse as narcolepsy, obesity, and addiction, as well as in our response to stress.
Likewise, orexin levels are altered in mental illnesses such as depression and anxiety disorders. They may also explain gender differences in stress response and are identified as a potential therapeutic target for treatment.
It is this incredible versatility that will help link our feeling of satiety to the irrepressible need to put our hands back in the candy box.
Why orexins make us want to eat more
To better understand it, we must return to its role in our diet.
The system that regulates the production of orexins is capable of detecting changes in the energy balance and increasing its levels through fasting response notably. And these molecules do not act alone: they interact with other proteins involved in appetite regulation, such as leptin and ghrelin.
the leptin it is a digestive hormone released by adipose tissue that regulates our fat reserves (which are a form of long-term energy storage) but also our appetite by inducing the feeling of satiety. the ghrelin, on the contrary, is a digestive hormone secreted by the stomach just before an expected meal. It works in the short term and stimulates hunger.
How do these two molecules work with our protagonists, namely the orexins?
Regulation of energy and appetite by orexin It is done using information from other areas of the hypothalamus, which record, among other things, changes in glucose, leptin and ghrelin levels.
Orexin-producing neurons are capable of integrating this information and triggering a response according to the needs of the organism. And unfortunately for us, it can associate food intake with a reward – Orexin A would also be related to some of the environmental factors at the origin of “craving” (this irrepressible need that is observed in addictions, where its role has also been identified) and relapse…
An important role throughout life.
But the impact of orexins is, as we have mentioned, much broader. There are times when the desire to eat is sometimes accentuated, for example during premenstruation or after menopause. What is behind these physiological requirements? Again, the relationship of the orexins has been investigated.
During menopause, sleep disturbances, weight gain, and increased anxiety are frequently described. To try to understand the scope of their regulatory capacities, we study how the levels of these hormones are modified in the body and if their variations can be associated with some of the symptoms observed. And in fact, there is a increased orexin A levels along with the reduction in estrogen levels that then occurs.
However, clinical studies to date are still inconclusive and no clear association between orexin A levels and other variables typical of the postmenopausal state. These include the impact of hormone replacement therapy on these levels, changes in sleep quality, and body mass index.
Links to eating disorders
Anorexia nervosa is particularly affected. This eating behavior disorder is characterized by being underweight (abnormally low weight, due to insufficient and unbalanced food intake), which stems from an altered perception of body image and an intense fear of gaining weight.
This significant malnutrition affects the entire body and gives rise to other clinical manifestations, ranging from the absence of menstruation to the deterioration of brain function. Recent studies suggest that orexin A levels and cognitive performance were lower in women with anorexia nervosa.
In addition, low levels of this hormone have also been found to be associated with less cognitive flexibility and poorer scores on psychological tests that assess decision-making in risky situations.
It remains to expand and confirm these results, which, however, open an interesting line of research that links neuropsychology and energy expenditure. Which perhaps more broadly understands the mechanisms by which they act and interact.
Green leafy vegetables and tea protect against cognitive decline
Flavonols are a class of antioxidant compounds found in tea, red wine, broccoli, beans, tomatoes, and leeks that have anti-inflammatory properties.
The data, mostly from animal studies, suggest that higher intakes of flavonols may protect against Alzheimer’s disease and dementia.
A recent longitudinal study found that higher dietary intake of flavonols was associated with a slowing of age-related decline in general and specific areas of cognitive function.
A recent study published in Neurology shows that a higher intake of flavonols, a category of flavonoids found in fruits, vegetables, tea, and wine, was associated with slower cognitive decline in older adults. The study adds to limited but growing data showing an association between dietary flavonol intake and brain health.
A healthy diet containing a variety of fruits and vegetables is essential for good health, especially brain health. In general, it is known that the vitamins and minerals present in these foods are important. But we now understand that it is the entire composition of the food, including bioactives like flavonols, that makes these foods beneficial.
Flavonoids and brain health
Flavonoids are a class of compounds produced by plants that possess antioxidant and anti-inflammatory properties. Flavonoids are found in commonly eaten fruits and vegetables, including berries, cherries, leafy greens, tomatoes, onions, apples, citrus fruits, and beans. Beverages such as tea and red wine are also important sources of dietary flavonoids.
Previous studies have shown that higher dietary intake of flavonoids is associated with slower cognitive decline that normally occurs with aging and also due to Alzheimer’s disease. These effects of flavonoids have been attributed to their ability to reduce oxidative stress, decrease inflammation in the brain, and increase brain plasticity.
There are six main subclasses of flavonoids, namely flavonols, flavan-3-ols, flavanones, flavones, isoflavones, and anthocyanins. Additionally, several compounds make up each subclass of flavonoids. For example, flavonols include compounds such as quercetin, kaempferol, isorhamnetin, and myricetin. Although animal studies suggest a beneficial impact of certain flavonols and their individual components on cognition, similar data from human studies is limited.
Does the intake of flavonols affect cognitive function?
The present study includes data from 961 participants who reside in Chicago retirement communities and public housing for the elderly and are enrolled in the Rush Memory and Aging Project. The Rush Memory and Aging Project is a longitudinal study whose objective is to identify the factors associated with the deterioration of cognitive and motor functions caused by aging and Alzheimer’s disease. Participants were between the ages of 58 and 100 and had not been diagnosed with dementia at the time of enrollment. The researchers annually assessed the participants’ cognitive function and risk factors associated with cognitive decline.
To assess cognitive function, a trained technician administered a battery of 19 tests spanning five different cognitive domains. These five areas were:
episodic memory: a form of long-term memory that encompasses memories of events and experiences
semantic memory: a form of long-term memory that encompasses factual and conceptual knowledge
working memory: a form of short-term memory that temporarily stores and manipulates information
perceptual speed: the ability to quickly process visual information
Visuospatial Ability: Ability to perceive spatial relationships and manipulate images mentally.
Based on overall performance on the 19 cognitive tests, the researchers quantified each participant’s overall cognitive function.
To assess dietary intake of flavonols and individual flavonol components, the researchers used a standardized questionnaire to estimate the frequency of consumption of flavonol-containing foods in the past year. The researchers then examined the association between dietary flavonol intake and cognitive function after adjusting for factors associated with cognitive decline, including age, gender, education level, smoking status, physical activity level, and participation in activities that enhance cognition. The analyzes suggested that a higher intake of flavonols was associated with a slower decline in general cognitive function.
In this study population, people who ate the most flavonols (an average of 7 servings of dark green leafy vegetables per week) compared to people who ate the least had a 32% decrease in their rate of deterioration cognitive.
2 Antioxidants Linked to Slower Decrease
Furthermore, higher consumption of flavonols (kaempferol and quercetin), but not isorhamnetin or myricetin, was associated with a slower decline in general cognitive function. Looking at changes in specific cognitive domains, the researchers found that higher flavonol intake was associated with slower declines in episodic memory, semantic memory, perceptual speed, and working memory, but not visuospatial ability.
Among individual flavonol components, higher kaempferol intake was associated with a slower rate of decline in all five cognitive domains. By contrast, myricetin was not associated with a change in cognitive abilities, but was suggestive for working memory. Quercetin consumption was associated with a more gradual decline in episodic and semantic memory, whereas isorhamnetin consumption was correlated with a more gradual decline in episodic and suggestive memory for visuospatial memory.
Leafy vegetables are the richest source of kaempferol. Tea, onions, leeks, broccoli, beans, tomatoes, and berries are some of the other main sources of other flavanols.
In addition to having beneficial effects on brain health, another recent study reported an association between increased intake of flavonoids, including flavonols, and a marker of subclinical atherosclerosis. This further highlights the potential protective effects of flavonoids on not only brain health but also cardiovascular health.
Eat eggs to lose weight, this is how
As part of a balanced diet, eggs can have many health benefits. A growing body of research suggests that eating eggs may also promote weight loss. Eggs are high in protein, low in calories, and can boost metabolism. In this article, we describe how to use eggs to aid weight loss, including when to eat them and how to prepare them.
Why are eggs good for weight loss?
Eggs can promote weight loss for three reasons:
1. Eggs are nutritious and low in calories.
Eggs are low in calories and high in protein.
One large hard-boiled egg contains 78 calories and several important nutrients, including:
lutein and zeaxanthin, which are antioxidants that promote good eyesight.
vitamin D, which promotes bone health and immune function
choline, which stimulates metabolism and contributes to fetal brain development.
The easiest way to lose weight is to reduce your calorie intake, and adding eggs to your diet can help with this.
For example, a lunch or dinner of two hard-boiled eggs and a cup of mixed vegetables is only 274 calories. However, cooking eggs with oil or butter significantly increases their caloric and fat content. A tablespoon of olive oil, for example, contains 119 calories.
2. Eggs are rich in protein
Protein helps with weight loss because it is extremely filling. Eggs are a good source of protein, with a large egg providing around 6 grams (g). The dietary reference intake for protein is 0.8 g per kilogram of body weight.
That means :
the average sedentary man needs 56 g of protein per day.
an average sedentary woman needs 46 g of protein per day.
Therefore, two large eggs provide more than 25% of the daily protein needs of the average sedentary woman and more than 20% of the needs of the average sedentary man.
Some research indicates that eating a high-protein breakfast increases a person’s satiety, or feelings of fullness. The results also suggest that a high-protein breakfast reduces calorie intake for the rest of the day. A 2012 study, published in the British Journal of Nutrition, suggests that dietary protein helps treat obesity and metabolic syndrome, in part because it makes you feel fuller.
3. Eggs can speed up metabolism
A high-protein diet can improve metabolism through a process called the thermic effect of food. This happens because the body has to use extra calories to digest and process the nutrients in food. Carbohydrates and fats also stimulate metabolism, but to a lesser extent than protein.
According to the results of a 2014 study:
Protein increases a person’s metabolic rate by 15-30%.
Carbohydrates increase metabolic rate by 5 to 10 percent.
Fat only increases metabolic rate by 3%.
Therefore, eating eggs and other protein-rich foods can help people burn more calories than eating carbohydrates or fat.
when to eat eggs
Research suggests that someone who eats an egg-based breakfast may consume less food throughout the day. Eggs can be especially helpful for weight loss if a person eats them for breakfast. In 2005, researchers compared the effects of eating an egg-based breakfast and a baked breakfast in overweight female participants. Both breakfasts had the same number of calories, but the participants who ate eggs ate significantly less food the rest of the day. In a 2013 study, adult men who ate eggs for breakfast needed smaller breakfasts and seemed to feel fuller than those who ate high-carb breakfasts.
However, it is still important to monitor your calorie intake. A 2008 study indicated that an egg-based breakfast promoted weight loss in overweight or obese participants, but only as part of a calorie-controlled diet.
How to eat eggs to lose weight
The key is to incorporate them into a healthy diet. It seems that eating eggs for breakfast is the best approach, as it can reduce the number of calories a person consumes for the rest of the day.
Eggs are nutritious and easy to prepare. People often like:
Serve them with vegetables for breakfast for a filling, fiber-rich meal, or add hard-boiled eggs to a salad for lunch. For a hearty dinner, top a salad of quinoa and sautéed vegetables with a poached egg.
How many eggs should a person eat?
Incorporating a moderate amount of eggs into a balanced diet may have health benefits. Recent research suggests that eating one egg a day may reduce the risk of heart disease and stroke. The researchers tracked the effects in nearly half a million adults living in China over a 9-year period.
However, it is important to note that the people in this study were not following the standard American diet. The authors of a 2018 study reported that eating at least 12 eggs a week for 3 months did not increase cardiovascular risk factors in participants with diabetes or prediabetes.
It is important to note that these participants followed a diet designed to lose weight. These results suggest that consuming a moderate amount of eggs can be beneficial for health, as long as the person incorporates them into a balanced diet. However, since egg yolks are high in cholesterol, people at risk for heart disease may want to limit themselves to one or two egg whites a day. You should also avoid adding animal fats, such as butter or bacon grease, to your egg meals.
Eggs are a low-calorie food rich in protein and other nutrients. Eating eggs can promote weight loss, especially if the person incorporates them into a low-calorie diet. Research suggests that eggs stimulate metabolic activity and increase feelings of satiety. Eating an egg-based breakfast can keep a person from consuming extra calories throughout the day. To promote weight loss, avoid preparing eggs by adding too much fat, butter or oils, for example.
If a person is at risk of cardiovascular disease, they should eat only egg whites and carefully monitor their cholesterol intake.
7 difficult foods to digest: to avoid at night!
Almost everyone has experienced the discomfort of indigestion at one time or another. If the causes are many, the consumption of foods that are difficult to digest is usually a determining factor. In this article, we are going to look at some difficult-to-digest foods that it is advisable to avoid, especially at night. Stay tuned !
Raw vegetables are difficult to digest because our body does not have the necessary enzymes for their breakdown. Enzymes are proteins that act as catalysts, speeding up chemical reactions in the body. The enzymes needed to digest raw vegetables are found in saliva and the pancreas.
Saliva begins the digestion process by breaking down starch into smaller molecules, while the pancreas produces enzymes that break down fats and proteins. When we eat raw vegetables, these enzymes are not present in sufficient quantity to properly digest the food. Cooked vegetables are easier to digest because the cooking process destroys some of the plant cell walls, allowing the enzymes to do their job more easily. Additionally, cooking kills bacteria that may be present on the surface of vegetables. These bacteria can cause food poisoning if they are not killed before eating. For these reasons, it is generally easier for our bodies to digest cooked vegetables than raw vegetables.
Although it may not seem like it, cruciferous vegetables are actually quite tough and fibrous. They contain a type of insoluble fiber, cellulose. Cellulose is difficult for the human body to break down, so cruciferous vegetables can be hard to digest. Additionally, cruciferous vegetables contain a compound called raffinose.
Raffinose is a complex sugar that cannot be completely broken down by the body. Therefore, it can ferment in the intestine, causing gas and bloating. For some people this can be quite uncomfortable. However, there are ways to make cruciferous vegetables more digestible. One way is to cook them, which breaks down the cellulose and makes them easier to chew. Another option is to eat smaller portions, since the body has a limited ability to break down insoluble fiber. By following these steps, you can enjoy the benefits of cruciferous vegetables without suffering digestive discomfort.
Anyone who has suffered from indigestion after eating a large slice of tomato pizza can attest to the fact that tomatoes can be hard to digest. There are many reasons for this. First of all, tomatoes contain a substance called lycopene, which is difficult for the body to break down.
Additionally, the skin and seeds of tomatoes are high in fiber, which can also lead to digestive problems. Finally, tomatoes are acidic and when they pass through the digestive system they can cause heartburn and indigestion. If you tend to have stomach problems, it is best to eat tomatoes in moderation. By removing the seeds and peeling them, you can still enjoy the nutritional benefits of tomatoes without the digestive upset.
When you eat spicy foods, your body reacts in a similar way to heat stress. Blood vessels dilate in an effort to cool the body, and sweating may occur. Saliva production is also increased to help cool the mouth and throat. However, all that extra fluid can make it difficult for the digestive system to function.
Additionally, spicy foods can irritate the lining of the intestine, leading to inflammation and discomfort. For some people, this can lead to heartburn, indigestion, or even diarrhea. If you feel a bit under the weather after enjoying a spicy dish, there’s a good reason for that.
Fruit juice :
Many people think that fruit juice is healthy and full of nutrients. However, they don’t always realize that fruit juices can be hard to digest. The reason is that fruits contain high levels of fructose, a type of sugar that is broken down by the liver. When the liver is overloaded with fructose, it can’t process it effectively. Some of the fructose can be converted to fat, which can then be deposited in the body. Furthermore, excessive consumption of fructose can also lead to intestinal problems such as bloating and diarrhea.
The alcohol :
Alcohol is a carbohydrate that the body cannot digest. When you drink alcohol, it is absorbed into your bloodstream and circulates throughout your body. The liver breaks down the alcohol and converts it into sugar, which the body can use as a source of energy. However, the liver can only process a small amount of alcohol at a time. If you drink too much alcohol, the excess sugar can build up in your blood and cause serious health problems. Also, alcohol irritates the lining of the stomach, which can make it difficult to digest food. Therefore, alcohol is hard on the liver and digestive system.
Animal protein tends to be high in fat, which can make it difficult to digest. Fat is a type of molecule that is not easily broken down by the digestive system. Therefore, they can remain in the stomach for a long time and cause indigestion. Furthermore, fats are also more difficult for the body to absorb. This means that when you eat high-fat animal protein, your body gets fewer nutrients than it needs. Difficulty digesting fats also explains why animal protein tends to be higher in calories than other types of food. When you eat animal protein that is high in fat, your body has to work harder to digest it, and as a result, you take in more calories than you would with a leaner protein source.
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