Your Microbiome Affects Your Mood
Can your diet change your mood? And does your gut health have anything to do with it?
Here is a fascinating new study that helps us better understand what we are starting to call the microbiota-gut-brain axis.
Researchers analyzed the diets and moods of people in 3 study groups (including people with mild depression). Here’s what they found:
🩸 Higher circulating levels of proline (an amino acid from food) in the blood plasma were linked with more severe depression.
🧬 Circulating levels of proline depended on the gut microbiota. Some people with high dietary consumption of proline did not have high proline in their blood circulation.
💛 People with high levels of proline in their diets but not in their blood circulation had more Bifidobacterium and microbes producing short-chain fatty acids in their gut microbiome (these are the healthy and helpful gut bugs!).
Whenever we see an “association” like this, we need to ask what came first? Does depression disrupt the microbiome, or does a disrupted microbiome cause depression?
The researchers in this study were extremely thorough. They went on to do fecal microbiota transplantation (FMT) from humans to mice to explore whether the microbiome could be causal in depression, and…
….the answer they got was YES!
It’s important to compare this to traditional treatment for depression. It is estimated that 300 million people worldwide suffer from depression. Traditional treatment (meds such as Selective Serotonin Reuptake Inhibitors and tricyclic antidepressants) only helps in 50% of those treated and relapse rates are about 40%.
I have written about the gut/brain axis in the past, a rapidly developing area of medical research for chronic illness. This study is specifically looking at the microbiome/gut/brain axis and its involvement in depression. This fascinating research takes the examination of the root cause of depression to a completely different level. If you like reading medical journals and studies, click the link below to look at their work. For those that don’t, I’ll distill the information for you. It is a long and very technically detailed article.
In this study, elevated circulating proline levels were consistently found to be associated with higher depression scores. Elevated proline levels have also been associated with epilepsy, schizophrenia, seizures, and dementia. Elevated proline levels have been shown to alter the communication between nerve cells in the nervous system by the neurotransmitters GABA and glutamate which have opposite effects on neurons.
The researchers in this study feel that one of the underlying root causes of depression is from elevated proline levels that alter the normal physiologic balance of GABA and glutamate in the synapses between neurons as they communicate. These researchers propose that dietary management to reduce proline consumption is a key to ameliorating depression symptoms.
So what foods contain a lot of proline? Here is a list:
|Proline (g)||Proline food sources (100 g)|
|12.295||Gelatins, dry powder, unsweetened|
|8.89||Gelatin desserts, dry mix, reduced calorie, with aspartame, added phosphorus, potassium, sodium, vitamin C|
|8.89||Gelatin desserts, dry mix, reduced calorie, with aspartame, no added sodium|
|7.262||Snacks, pork skins, plain|
|6.769||Snacks, pork skins, barbecue-flavor|
|4.96||Soy protein isolate, potassium type|
|4.96||Soy protein isolate, potassium type, crude protein basis|
|4.96||Soy protein isolate|
|4.86||Cheese, parmesan, shredded|
|4.622||Cheese, parmesan, grated|
|4.5||Soy protein isolate, PROTEIN TECHNOLOGIES INTERNATIONAL,SUPRO|
|4.4||Soy protein isolate, PROTEIN TECHNOLOGIES INTERNATIONAL, ProPlus|
|4.18||Cheese, parmesan, hard|
|3.789||Seal, bearded (Oogruk), meat, dried (Alaska Native)|
|3.693||Cheese, goat, hard type|
|3.503||Milk, dry, nonfat, regular, with added vitamin A and vitamin D|
|3.503||Milk, dry, nonfat, regular, without added vitamin A and vitamin D|
|3.481||Whale, beluga, meat, dried (Alaska Native)|
|3.439||Milk, dry, nonfat, calcium reduced|
|3.4||Milk, dry, nonfat, instant, with added vitamin A and vitamin D|
|3.4||Milk, dry, nonfat, instant, without added vitamin A and vitamin D|
|3.322||Milk, buttermilk, dried|
|3.298||Soy protein concentrate, produced by acid wash|
|3.298||Soy protein concentrate, produced by alcohol extraction|
|3.298||Soy protein concentrate, crude protein basis (N x 6.25), produced by acid wash|
|3.259||Egg, white, dried, stabilized, glucose reduced|
|3.231||Cheese, parmesan, dry grated, reduced fat|
|3.153||Egg, white, dried|
|3.098||Egg, white, dried, powder, stabilized, glucose reduced|
|2.98||Fish, whitefish, dried (Alaska Native)|
|2.892||Egg, white, dried, flakes, stabilized, glucose reduced|
|2.892||Cheese, port de salut|
|2.862||Seal, bearded (Oogruk), meat, partially dried (Alaska Native)|
|2.848||Pork, fresh, variety meats and by-products, ears, frozen, raw|
|2.81||Spices, mustard seed, ground|
|2.766||Cheese, provolone, reduced fat|
|2.754||Spices, poppy seed|
|2.753||Cheese, mozzarella, part skim milk, low moisture|
|2.75||Soy flour, defatted, crude protein basis (N x 6.25)|
|2.75||Soy flour, defatted|
|2.722||Soy flour, low-fat, crude protein basis (N x 6.25)|
|2.7||Spices, basil, dried|
|2.629||Soy meal, defatted, raw, crude protein basis (N x 6.25)|
|2.629||Soy meal, defatted, raw|
|2.612||Cheese, goat, semisoft type|
|2.586||Tofu, dried-frozen (koyadofu), prepared with calcium sulfate|
|2.586||Tofu, dried-frozen (koyadofu)|
|2.58||Cheese, Mexican blend|
|2.549||Milk, dry, whole, with added vitamin D|
|2.549||Milk, dry, whole, without added vitamin D|
|2.526||Cheese, low fat, cheddar or colby|
|2.526||Cheese, low-sodium, cheddar or colby|
|2.516||Cheese, pasteurized process, swiss|
|2.498||Cheese, mozzarella, part skim milk|
|2.494||Seeds, sunflower seed flour, partially defatted|
|2.403||Cheese, mexican, queso asadero|
|2.382||Seaweed, spirulina, dried|
|2.379||Soybeans, mature seeds, raw|
|2.365||Mollusks, whelk, unspecified, cooked, moist heat|
|2.36||Smelt, dried (Alaska Native)|
|2.351||Cheese, mozzarella, whole milk|
|2.321||POPEYES, Fried Chicken, Mild, Wing, meat only, skin and breading removed|
|2.32||Cheese spread, pasteurized process, American|
|2.315||Soybeans, mature seeds, dry roasted|
|2.304||Peanut flour, defatted|
|2.3||KENTUCKY FRIED CHICKEN, Fried Chicken, EXTRA CRISPY, Wing, meat only, skin and breading removed|
|2.289||Seeds, sesame flour, low-fat|
|2.254||Beef, cured, breakfast strips, cooked|
|2.251||Cheese, pasteurized process, pimento|
|2.249||Cheese, mexican, queso chihuahua|
|2.241||Cheese, goat, soft type|
|2.237||KENTUCKY FRIED CHICKEN, Fried Chicken, ORIGINAL RECIPE, Wing, meat only, skin and breading removed|
|2.23||Cheese food, pasteurized process, swiss|
|2.226||Turkey, skin from whole (light and dark), roasted|
|2.224||POPEYES, Fried Chicken, Mild, Breast, meat only, skin and breading removed|
|2.224||Cheese, mozzarella, whole milk, low moisture|
|2.221||Fish, cod, Atlantic, dried and salted|
|2.187||KENTUCKY FRIED CHICKEN, Fried Chicken, EXTRA CRISPY, Breast, meat only, skin and breading removed|
|2.18||Lasagna, Cheese, frozen, prepared|
|2.151||Cheese, mexican, queso anejo|
|2.147||KENTUCKY FRIED CHICKEN, Fried Chicken, ORIGINAL RECIPE, Breast, meat only, skin and breading removed|
|2.127||POPEYES, Fried Chicken, Mild, Drumstick, meat only, skin and breading removed|
|2.125||Seeds, cottonseed flour, low fat (glandless)|
|2.111||KENTUCKY FRIED CHICKEN, Fried Chicken, ORIGINAL RECIPE, Drumstick, meat only, skin and breading removed|
|2.103||Pork, cured, bacon, cooked, broiled, pan-fried or roasted|
|2.094||Seeds, cottonseed meal, partially defatted (glandless)|
|2.089||Beef, variety meats and by-products, lungs, cooked, braised|
|2.084||Spaghetti, protein-fortified, dry, enriched (n x 6.25)|
|2.084||Macaroni, protein-fortified, dry, enriched, (n x 5.70)|
|2.084||Macaroni, protein-fortified, dry, enriched, (n x 6.25)|
|2.084||Spaghetti, protein-fortified, dry, enriched (n x 5.70)|
|2.078||KENTUCKY FRIED CHICKEN, Fried Chicken, EXTRA CRISPY, Drumstick, meat only, skin and breading removed|
|2.075||Wheat flour, whole-grain|
|2.06||Soybeans, mature seeds, roasted, no salt added|
|2.06||Soybeans, mature seeds, roasted, salted|
|2.06||Turkey, enhanced, skin from whole, (light and dark), roasted|
|2.035||Soy flour, full-fat, roasted|
Here is a little excerpt from the book Super Gut by William Davis MD.
“It’s been known for years that about a third of people who experience depression…show increased measures of inflammation such as C-reactive protein and other markers. The same people who show increased markers of inflammation with depression are also those most likely to prove resistant to prescription antidepressant medications.
In a number of clinical studies, brave volunteers without depression have willingly received injections of the LPS (lipopolysaccharide) endotoxin derived from the cell walls of bacteria. Within hours of receiving this artificial increase in LPS, they developed the signature emotions of depression: dark mood, anxiety, loss of motivation, disinterest in everyday activities, and impaired cognitive function. Imaging of brain function in these people revealed all the brain hallmarks of depression. The conclusion: the products of bacterial breakdown that enter the bloodstream play a role in causing depression, especially in those unresponsive to conventional treatment. ….Lost from these observations is the fact that, outside of these artificial situations in which LPS is directly injected, the high levels of LPS circulating in the bloodstream of many people in everyday life originate with bacterial overpopulation that leads to endotoxemia.”
Dr. Davis’ recommendation for this issue is homemade yogurt containing Lactobacillus helveticus and Bifidobacterium longum with an addition of L. casei and he has a recipe in his book.
There are so many details I could unpack from this study, but for now, I’ll leave it at this.
🥗 The foods you eat can influence your mood, but what might be even more important is the health of your gut microbiome. So now the question becomes—what are you doing to nourish your gut?
Mayneris-Perxachs J, Castells-Nobau A, Arnoriaga-Rodríguez M et al. Microbiota alterations in proline metabolism impact depression. Cell Metab . 2022; 34: 681-701.