Keep Your Brain Fit By Keeping Your Gut Healthy
March 22, 2016More and more people are focusing on brain health and with good reason. As Americans live longer, age-related diseases like Alzheimer’s are rising. |
According to AARP’s 2015 survey 93 percent of Americans consider brain health important but few know how to improve or maintain it. And while many people may be aware that exercising regularly, managing stress and being social can help keep the mind sharp, many Americans don’t realize that brain diseases are intimately connected to our gut bacteria (also known as gut microbiome).
Bacteria that live on us and inside us outnumber our cells by 10 to 1. The majority of bacteria resides in our gut and has existed for billions of years, evolving with us and adapting to our dietary changes over the past 2 million years.
The number of functions that our gut microbiome is responsible for is staggering and include:
- Maintaining immune system functions
- Controlling inflammation
- Producing neurotransmitters and vitamins
- Absorbing nutrients
- Chemical signaling of hunger or fullness
- Eliminating toxins from food
- Utilizing carbohydrates and fats
- Managing weight
But how is the gut connected to the brain? The vagus nerve, which runs from the brain to the abdomen, receives signals from bacteria to initiate processes.
Scientists have been studying this connection for years¬--and they're starting to get a better understanding of gut biome deficiencies. For example, researchers engineered germ-free rats. These rats suffered from acute anxiety, inability to handle stress, chronic gut inflammation, generalized inflammation and lower levels of BDNF (brain-derived neurotropic factor). In humans, higher BDNF levels are linked with preserving cognitive function and the volume of the larger hippocampus (brain’s center for memory and emotion). The issues seemed to reverse themselves after feeding the rats a diet rich in the bacteria Lactobacillus helveticus and Bifidobacterium longum, present in many probiotics.
What causes low gut bacteria levels?
- Being born via Cesarean section (C-section) – investigators from the University of Colorado released a study that linked C-section births with lower bacteria. As a fetus goes through the birth process, he/she is colonized with Lactobacillus; whereas, infants born via C-section are colonized with a skin bacteria like staph, which can lead to potential health issues later in life. Moreover, women who give birth by C-section receive IV antibiotics that sterilize the gut. That said, many studies have suggested that babies born by C-section have a higher risk of allergies, ADHD, autism, celiac, type 1 diabetes and later-life obesity. Certainly, these are complex diseases with multifactorial causes, but there is a lot of data supporting this association. The same held true for formula feed babies versus nursed babies.
- Eating a Western diet – researchers have found that many foods in the Western diet produce microbiota that have less healthy bacteria (Bacteroidetes) and more unhealthy bacteria (Firmicutes). We can measure the ratio of Firmicutes to Bacteroidetes to determine the health of the microbiome in an individual. Because Firmicutes help extract calories from carbohydrates in food and uptake fats, they have been linked to obesity. Bacteroidetes do not have the same capability, so when they predominate, there is a lower likelihood of obesity.
- Having early stage Alzheimer's disease – some experts refer to Alzheimer’s disease as type 3 diabetes. Studies demonstrate a strong correlation between elevated blood sugar, even within the “normal” range, and the development of Alzheimer’s disease. Nerves and brain cells are particularly susceptible to the elevations of blood glucose and the advanced glycation end products (AGEs), which form when glucose binds to proteins on nerves and brain cells causing damage. Certain foods and supplements like coffee, tea, chocolate, wine and berberine seem to help control blood sugar because they exert anti-diabetic/anti-inflammatory effects on gut bacteria. Studies also suggest that good bacteria produces important brain chemicals such as GABA, glutamate and BDNF; low levels of these chemicals have been linked to Alzheimer’s disease.
- Having leaky gut syndrome – physicians use this term when certain proteins pass into the bloodstream. It generally occurs when the tight intracellular junctions between cells become “leaky," allowing proteins such as lipopolysaccharide (LPS) to enter the bloodstream. LPS a major component of the outer membrane of Gram-negative bacteria, which can cause pneumonia, blood infections and meningitis. It can also cause a significant inflammation within the body. Researchers have reported that the plasma of Alzheimer’s patients has three times the concentration of LPS. The level of LPS in the blood also correlates with the severity of the disease. Similar data exist among people with Parkinson’s disease. Lifestyle choices such as limiting antibiotic usage, eating a balanced diet and managing stress can help prevent leaky gut syndrome.
- Eating too much fructose – dietitians explain that fructose is the sugar found in fruit and is the sweetest of all naturally occurring sweeteners. However, eating fruit is not the problem. The real issue is eating processed fructose, such as high-fructose corn syrup, a manufactured version of fructose that is found in many processed foods. Our gut bacteria rapidly consumes and processes fructose into byproducts that disrupt the gut barrier and impair insulin sensitivity. Additionally, fructose is metabolized by the liver, which converts it into abdominal fat and increases insulin resistance even more. According to studies, high-fructose corn syrup can increase your risk of diabetes.
- Eating too much gluten – some researchers believe that gluten is one of the most inflammatory ingredients available. Although celiac disease is not common, many people struggle with gluten sensitivities. Gluten is comprised of two main proteins, glutenins and gliadins. Dr. Alessio Fasano, a distinguished Harvard scientist, believes that gliadin increases gut permeability; this can cause certain proteins to leak into the bloodstream, increasing sytematic inflammation and autoimmune diseases. Further, anti-gliadin antibodies bind to a brain protein, which contributes to breaking down the brain barrier permeability, exposing the brain to the inflammatory chemicals and harmful antibodies.
- Limiting your antibiotics usage – scientists have found that antibiotics tend to wipe out certain strains of gut bacteria, leaving an imbalance that favors obesity-producing bacteria. This is one reason why cattle are routinely given antibiotics – it fattens them. And guess who gets a dose of antibiotics any time we consume meat?