Gut feelings: How food affects your mood

We spend our days interacting with the world around us through our senses of sight, sound, and touch. But anyone who has developed complete nasal obstruction from an infection or severe allergies has experienced what it’s like to be without one of our most basic senses: our sense of smell.
The many functions of smell

In other animals, the sense of smell is absolutely crucial for survival, reproduction, and rearing of young. Although humans can survive without smell, research has shown that losing the sense of smell negatively impacts quality of life, even driving some people toward clinical depression. Just as other animals depend on the sense of smell as an alarm system for danger, we also depend on smell to warn us of the hazards of smoke from a fire, natural gas leaks in the home, and spoiled food.

On a daily basis, smell rounds out our experiences and is often an integral part of our memory of events from years gone by. Memories of a perfume worn by your spouse or the bread being baked at your grandmother’s house when you were a child last for decades, and are often intricately tied in with strong emotions.

The flavor of a meal depends heavily on the ability to smell, and without it, eating is just a bland means to dispel hunger. With so much of our social activity involving congregating at restaurants, bars, and cafes, it is understandable how someone losing the sense of smell can develop a sense of alienation.
Impact of smell disorders

Smell disorders affect 19% of the population over the age of 20 and 25% of the population over 53. If smell loss from aging alone is considered, one out of eight people between 53 and 91 will be affected over a five-year period. The detrimental effect of smell loss on flavor of food could significantly impact the elderly population, where diet and nutrition are already often a concern.

The sense of smell (olfaction) is dependent on millions of specialized nerve cells that are located in a deep protected recess high in the nasal cavity. Remarkably, these nerve cells normally die and are replaced throughout our lifetime. Therefore, the system has the capacity to repair itself after injury, but this isn’t always possible or complete.

The most common causes of prolonged smell loss occur as a result of upper respiratory infection, head injury, chronic sinus disease, and aging. However, other conditions such as Alzheimer’s disease, Parkinson’s disease, and tumors can be associated with smell loss.

In some cases, the loss of smell is complete (anosmia), while in other cases there is only a partial loss (hyposmia). In many instances where smell loss occurs, remaining smells are distorted. The distortions are either experienced as odors smelling dramatically different from what was remembered (parosmia) or smelling an odor that isn’t present (phantosmia).

Perhaps if they were pleasant, these distortions of smell might not be as distressful. However, in almost all instances, the experienced smells are unpleasant, with “smoke,” “swamp-like,” “musty,” “garbage,” or “chemical-like” among some very common descriptions. The odor is usually hard for people to describe, since it is not like anything they have experienced before.
Treating smell disorders

In cases where smell loss results from sinus disease, we have had some success in treating the condition. Oral and topical steroids often provide relief. Sometimes surgery is required to reduce the obstruction of odors to the sensory nerve cells. Sinus disease usually requires long-term management, and fluctuations in the ability to smell are common.

In contrast to chronic sinus inflammation, success in treating people with loss of smell resulting from head injury, upper respiratory infection, or aging is poor. The natural ability of the olfactory system to repair itself allows for some patients to regain the sense of smell after a respiratory infection-related loss or head injury. This recovery can take over a year, and can be so gradual that people have difficulty recognizing the change. Predicting whether recovery will occur in an individual is usually not possible, but overall any improvement that occurs within a one-year period increases the chances of recovery.

If you experience any persistent change in your sense of smell, visit your doctor for an evaluation. Some rare forms of smell disorders may result from tumors in the brain, neurodegenerative disease, or infection. These conditions should be diagnosed expediently for proper management and treatment. In addition, your doctor should talk to you about risks, such as depression and nutritional concerns that may stem from loss of smell.

Although therapies are currently lacking, there is hope for future breakthroughs. Ongoing scientific work is investigating how stem cells in the nose replace dying olfactory nerve cells. In the future, we will be able to add medication in the nose to trigger these cells to make more neurons, or replace missing stem cells to regenerate the neurons. Or we may be able to electrically stimulate a sensation of smell using an artificial implant. Continued research advances in this field will someday allow us to restore this important sensory system to those unfortunate enough to experience smell disorders, and provide them with the ability to once again fully experience the world around them.
It’s the holiday season, time for buying toys for the children in our lives. As we do, the American Academy of Pediatrics (AAP) encourages us to think about buying toys that can actually help children as they grow and develop.

Play is the work of children. That doesn’t mean it can’t be fun; of course play should be fun. But play is at its best when it encourages learning and development, and when it encourages interaction with other people. So many gifts these days are full of bells and whistles and cool electronic gadgets, but don’t really help children (and are often quickly discarded). The AAP thinks that when buying gifts for children we should think more about getting back to basics, and suggests we think about toys from traditional toy categories:

    Symbolic/pretend play. These toys are the building blocks for imaginative play. They are things like dolls, animals, dollhouses, kitchen sets, tool sets, dress-up costumes, or puppets. Children can use them to create their own stories, doing it differently each time. Simple is best: toys don’t need to walk or talk or do anything, really. It’s better to leave that up to children.
    Fine motor/adaptive/manipulative. These are things like actual building blocks and other building sets, train sets, or puzzles. These are toys that not only encourage children to build and create, but also encourage fine motor skill development and early math (and even engineering) skills. There are apps that allow kids to build things digitally, but using their hands is best; nothing outdoes the three-dimensional approach.
    Art. Nothing encourages creativity and fine motor skills better than drawing, painting, and building with clay. So buy paper, crayons, markers, paint and paintbrushes — and modeling clay. They are inexpensive gifts that can keep children happy for hours. There is something very powerful for development when children have to start a project from scratch, like a drawing from a blank piece of paper.
    Language and interaction. This is where books come in — there is nothing better for learning new words, and appreciating words, than books. And when they are read aloud, in someone’s lap, they encourage interaction, which helps children flourish. Games encourage interaction too; traditional board games can be fun for everyone, and bring people together.
    Gross motor. In general, we are a sedentary nation — and most children do not get the recommended hour of physical activity every day. So make it easier for them. Buy them a bike or a trike, or a basketball and a net, or a soccer ball or a jump rope. Anything you do to get them moving not only builds strength and skills, it builds habits that can keep children healthy for the rest of their lives.
The human microbiome, or gut environment, is a community of different bacteria that has co-evolved with humans to be beneficial to both a person and the bacteria. Researchers agree that a person’s unique microbiome is created within the first 1,000 days of life, but there are things you can do to alter your gut environment throughout your life.
Ultra-processed foods and gut health

What we eat, especially foods that contain chemical additives and ultra-processed foods, affects our gut environment and increases our risk of diseases. Ultra-processed foods contain substances extracted from food (such as sugar and starch), added from food constituents (hydrogenated fats), or made in a laboratory (flavor enhancers, food colorings). It’s important to know that ultra-processed foods such as fast foods are manufactured to be extra tasty by the use of such ingredients or additives, and are cost effective to the consumer. These foods are very common in the typical Western diet. Some examples of processed foods are canned foods, sugar-coated dried fruits, and salted meat products. Some examples of ultra-processed foods are soda, sugary or savory packaged snack foods, packaged breads, buns and pastries, fish or chicken nuggets, and instant noodle soups.

Researchers recommend “fixing the food first” (in other words, what we eat) before trying gut modifying-therapies (probiotics, prebiotics) to improve how we feel. They suggest eating whole foods and avoiding processed and ultra-processed foods that we know cause inflammation and disease.
But what does my gut have to do with my mood?

When we consider the connection between the brain and the gut, it’s important to know that 90% of serotonin receptors are located in the gut. In the relatively new field of nutritional psychiatry we help patients understand how gut health and diet can positively or negatively affect their mood. When someone is prescribed an antidepressant such as a selective serotonin reuptake inhibitor (SSRI), the most common side effects are gut-related, and many people temporarily experience nausea, diarrhea, or gastrointestinal problems. There is anatomical and physiologic two-way communication between the gut and brain via the vagus nerve. The gut-brain axis offers us a greater understanding of the connection between diet and disease, including depression and anxiety.

When the balance between the good and bad bacteria is disrupted, diseases may occur. Examples of such diseases include: irritable bowel disease (IBD), asthma, obesity, metabolic syndrome, diabetes, and cognitive and mood problems. For example, IBD is caused by dysfunction in the interactions between microbes (bacteria), the gut lining, and the immune system.
Diet and depression

A recent study suggests that eating a healthy, balanced diet such as the Mediterranean diet and avoiding inflammation-producing foods may be protective against depression. Another study outlines an Antidepressant Food Scale, which lists 12 antidepressant nutrients related to the prevention and treatment of depression. Some of the foods containing these nutrients are oysters, mussels, salmon, watercress, spinach, romaine lettuce, cauliflower, and strawberries.

A better diet can help, but it’s only one part of treatment. It’s important to note that just like you cannot exercise out of a bad diet, you also cannot eat your way out of feeling depressed or anxious.

We should be careful about using food as the only treatment for mood, and when we talk about mood problems we are referring to mild and moderate forms of depression and anxiety. In other words, food is not going to impact serious forms of depression and thoughts of suicide, and it is important to seek treatment in an emergency room or contact your doctor if you are experiencing thoughts about harming yourself.