Probiotics are amazing. Not only do they improve our GI tract, they also balance the immune system, fight infections and allergies and improve our mood and cognitive function. Read on to learn how these “good bacteria” enhance our mood, combat stress and help with obesity and diabetes.
- Probiotic Four Part Series
- Health Benefits of Probiotics
- 1) Probiotics can Increase Vitamin Levels
- 2) Probiotics can Increase Iron Levels
- 3) Probiotics can Increase Minerals
- 4) Probiotics Act as Antioxidants
- 5) Probiotics May be Neuroprotective
- 6) Probiotics May Improve Cognitive Function
- 7) Probiotics Improve our Mood
- 8) Probiotics Combat Depression
- 9) Probiotics Reduce Anxiety
- 10) Probiotics May Alleviate OCD
- 11) Probiotics may Ameliorate Autism
- 12) Probiotics May be Beneficial in Schizophrenia
- 13) Probiotics Combat Stress
- 14) Probiotics Improve the Sleep-Wake Cycle
- 15) Probiotics can Reduce Weight
- 16) Probiotics Combat Obesity
- 17) Probiotics Reduce Glucose and Improve Insulin Sensitivity
- 18) Probiotics are Beneficial in Diabetes
- 19) Probiotics Reduce Bad Cholesterol
- 20) Probiotics Increase Good Cholesterol
- 21) Probiotics Reduce Blood Pressure
- Buy Probiotics
- Further Reading
Probiotic Four Part Series
- Probiotic benefits 1-21 (Part 1)
- Probiotic benefits 22-26 (Part 2)
- Probiotic benefits 27-36 (Part 3)
- Probiotic benefits 37-61 (Part 4)
At birth, the sterile human gut is immediately colonized with several types of microorganisms from both the mother and the environment. By the time they reach one year of age, each individual develops a unique bacterial profile (R).
It is estimated that only 10% of the cells in the human body actually belong to the body itself. The overwhelming majority of the cells consist of the diverse microbiota of nonpathogenic bacteria, 1-2 kg of them living in the gut alone (R).
Gut microbiota includes ~30 species of Bifidobacterium, 52 species of Lactobacillus, and others, such as Streptococcus and Enterococcus (R).
The genome of the entire gut microbiota named as “microbiome” exceeds the human nuclear genome by at least 100 times (R).
Human gut microorganisms are strongly involved in diverse metabolic, nutritional, physiological, and immunological processes (R). They play an important role in energy homeostasis and through the microbe–gut–brain axis (R) they impact our mood and cognitive abilities. They also stimulate the immune response, prevent pathogenic and opportunistic microbes/bacteria, and produce vitamins such as B and K (R).
Diet can exert a profound effect on the gut microbiota profile, and people in different parts of the world have different bacterial profiles (R). For example, there is an association of Bacteroides and high animal fat or protein diets, while Prevotella is associated with a high carbohydrate diet (R).
Probiotic bacteria are live microorganisms known as “friendly gut bacteria” which when present and/or administered in adequate amounts can have potential health benefits (R).
The term “probiotic” comes from the Greek term ‘for life’ (R).
Probiotics have been regarded as beneficial since ancient times (particularly lactic acid bacteria – Lactobacilli and Bifidobacteria), but they came into spotlight in the late 1800s and early 1900s, when it was proposed that consuming yogurt containing Lactobacillus would decrease toxin-producing bacteria in the gut and increase longevity (R).
Naturally occurring probiotic bacteria exist in fermented food products such as yoghurt, kefir, sauerkraut, cabbage kimchee and soy bean based miso and natto (R).
The most common probiotic strains belong to the species Lactobacillus and Bifidobacterium, followed by the genera Streptococcus, Enterococcus, Propionibacterium, Bacillus, and Escherichia. In addition, some yeast species are used as probiotics, for example, S. boulardii and S. cerevisiae (R,R).
Probiotics can enhance the immune system, improve the skin’s function, enhance resistance against allergens, and decrease body pathogens (R). They have anti-inflammatory effects, they improve blood lipid profile and glucose tolerance (R), and lower blood pressure and the BMI (R).
Note that in clinical studies, probiotic mixtures are often demonstrated to be better than a single strain for improving indigenous microflora (R).
Prebiotics are specific carbohydrates, such as polysaccharides, fructans, and inulins, that can exert beneficial effects on the composition and metabolic activities of gut microorganisms. A diet high in inulin and related fibers, for example, has been shown to increase Bifidobacteria (R).
A prebiotic and probiotic combination is referred to as a Synbiotic, when the net health benefit is synergistic (R).
Health Benefits of Probiotics
1) Probiotics can Increase Vitamin Levels
Folate-rich fermented milk produced by high-folate-producing S. thermophilus increases hemoglobin levels in mice (R).
2) Probiotics can Increase Iron Levels
Iron deficiency in young women in south India was associated with low levels of Lactobacilli (R).
3) Probiotics can Increase Minerals
4) Probiotics Act as Antioxidants
A B. subtilis signal molecule induces the heat shock protein Hsp27 in mammalian cells, which protects intestinal cells against oxidant-mediated tissue damage (R).
5) Probiotics May be Neuroprotective
The probiotic you want: C. butyricum
C. butyricum, furthermore, restores butyrate in the brain, reduces neuronal cell death, and significantly attenuates cognitive dysfunction and histopathological changes in mice with vascular dementia (R).
C. butyricum also exerts neuroprotective effects against ischemia/reperfusion injury in mice (R), and attenuates cognitive impairment, cell damage and neuronal death in diabetic mice with cerebral ischemia/reperfusion injury (R).
6) Probiotics May Improve Cognitive Function
Try: L. helveticus
Gut probiotics play a major role in the bidirectional communication between the gut and the brain (R), referred to as the “microbiota-gut-brain” axis. It is now generally accepted that microbiota can affect behavior and modulate cognitive function (R).
Probiotics improve both spatial and non-spatial memory (R). Probiotics administration considerably improved the impaired spatial memory and efficiently reversed deteriorated brain in diabetic rats (R,R).
Germ-free mice display deficits in non-spatial and working memory. Also, mice that were exposed to gut bacterial infection and stress exhibited memory deficits, while probiotic treatment 7 days before and during the infection prevented cognitive dysfunction (R).
L. plantarum was shown to improve learning and memory in rats with vascular dementia, by acting as a blood pressure-lowering and neuroprotective agent (R).
Finally, L. casei potentiates the effect of proanthocyanidins extracted from lotus seedpod, and ameliorates memory impairments in mice (R).
7) Probiotics Improve our Mood
The vast assemblage of microorganisms in our intestines may have a major impact on our state of mind (R). Gut microorganisms are able to produce and deliver such neuroactive substances as serotonin and gamma-aminobutyric acid (GABA) (R).
A multispecies probiotic containing B. bifidum, B. lactis, L. acidophilus, L. brevis, L. casei, L. salivarius, and L. lactis reduces cognitive reactivity to sad mood in non-depressed individuals, which was largely accounted for by reduced rumination and negative thoughts (R).
An inverse association between constipation and feelings of calmness, elatedness and agreeableness was found, i.e. frequent constipation was associated with a poorer mood state. A probiotic multivitamin compound significantly improved the general condition of those who participated in the study with a 41% improvement in stress, a 29% decrease in the prevalence of infection and a 91% reduction in GI discomfort (R).
Probiotic yogurt improved the mood of those with an initially poor mood (R).
Consuming a probiotic yogurt or a multispecies probiotic capsule for six weeks had beneficial effects on the mental health biomarkers of petrochemical workers (R).
8) Probiotics Combat Depression
A correlations was found between human microbiota and depression. Probiotics significantly decreased depression scores in both healthy individuals and patients with major depressive disorder under 60 years of age (R).
L. helveticus and B. longum reduced depression in healthy volunteers when they were taken regularly (R).
A mix of L. acidophilus, L. casei and B. bifidum decreased depression, and in addition lowered insulin levels, insulin resistance and hs-CRP and increased glutathione levels in patients with major depressive disorder (R).
Chronic administration of B. infantis protects rats from depressive symptoms caused by stress induced through maternal separation (R).
9) Probiotics Reduce Anxiety
Try L. helveticus and/or B. longum
Infecting healthy mice with pathogenic bacteria stimulates anxiety behaviors within hours of infection suggesting that changes in the gut microbiota can very quickly induce biochemical changes in the brain (R).
10) Probiotics May Alleviate OCD
11) Probiotics may Ameliorate Autism
There is a potential role of intestinal microorganisms in the complex pathophysiology of autism spectrum disorder (ASD). Treatment of an autism mouse model with probiotics ameliorated ASD-related traits (R).
In an animal model of social deficits in offspring, L. reuteri was found to be 9X lower. Supplementing with it increased oxytocin levels and significantly improved sociability and preference for social novelty in mice offspring (R).
12) Probiotics May be Beneficial in Schizophrenia
13) Probiotics Combat Stress
Stressed out? Try: L. casei and/or B. bifidum
In stressed rats, L. casei suppressed blood corticosterone levels (R).
Similarly, when L. casei was administered to medical students undertaking an authorized nationwide examination to test their response to stress, this bacterium increased serotonin levels, lowered the rate of subjects experiencing common abdominal and cold symptoms and decreased the total number of days students experienced these symptoms (R).
In academically stressed undergraduate students, B. bifidum increased the proportion of healthy days per participant and decreased the percentage of participants reporting cold/flu during the intervention period (R).
14) Probiotics Improve the Sleep-Wake Cycle
L. helveticus-fermented milk significantly improved sleep efficiency in healthy elderly people (R).
Daily voluntary wheel-running and sleep rhythmicity became intensified in mice when heat-killed L. brevis was added to the diet (R).
15) Probiotics can Reduce Weight
Look for: L. rhamnosus and/or L. gasseri
Consuming probiotics can reduce body weight and BMI. A greater effect is achieved in overweight subjects, when multiple species of probiotics are consumed in combination or when they are taken for more than 8 weeks (R).
L. gasseri significantly decreased body weight and visceral and subcutaneous fat areas in adults with obese tendencies (R).
Despite there being no change in behavior or diet, administration of L. gasseri modestly reduced weight and waist and hip circumference in obese and overweight adults (R).
L. gasseri significantly decreased BMI, abdominal visceral fat, waist and hip circumferences, and body fat mass in healthy Japanese adults. However, constant consumption of this probiotic may be required to maintain this effect (R).
16) Probiotics Combat Obesity
Intestinal microbiota can affect host adiposity and regulate fat storage (R).
Bifidobacteria content was higher in children of normal weight than those who were showing signs of becoming overweight (R). Similarly, the presence of B. animalis was found to be negatively associated with BMI in humans (R,R).
The intake of synbiotics (probiotics + prebiotics) in obese children resulted in a significant reduction in BMI, waist circumference, and some cardiometabolic risk factors, such as TC, LDL-C and TAG (R).
Daily ingestion of milk containing B. animalis ssp. lactis significantly reduced the BMI, total cholesterol, low-density lipoprotein, and inflammatory markers in humans (R).
B. breve lowered fat mass and improved GGT and hs-CRP in adults with obese tendencies (R).
L. rhamnosus improved liver parameters in obese children with liver dysfunction noncompliant with lifestyle interventions (R).
L. paracasei decreases energy/food intake in both human and animal subjects (R).
Oral administration of B. longum, B. bifidum, B. infantis, and B. animalis decreased glucose levels, ameliorated insulin resistance and reduced the expressions of inflammatory adipocytokines in obese mice (R).
B. breve reduced body weight gain and accumulation of visceral fat in a dose-dependent manner, and improved serum levels of total cholesterol, fasting glucose and insulin in a mouse model of diet-induced obesity (R).
C. butyricum reduced fat accumulation in liver and blood, lowered insulin levels and improved glucose tolerance and insulin sensitivity in obese mice. Furthermore, C. butyricum administration ameliorated GI and fat tissue inflammation (R).
Water extract of L. paracasei reduced body weight in obese rats. It decreased the formation of lipid plaques in the aorta, reduced fat cell size and inhibited fat absorption, thereby reducing fat production (lipogenesis) (R).
NOTE: Although some studies show beneficial effects of L. reuteri in obesity-related symptoms, in one study, this species was associated with obesity in humans (R).
17) Probiotics Reduce Glucose and Improve Insulin Sensitivity
L. plantarum reduced glucose levels in postmenopausal women (R).
L. plantarum caused a significant reduction of blood glucose levels in response to insulin in mice on a high-fat-diet (R).
18) Probiotics are Beneficial in Diabetes
Gut microbiota of adults with T2DM is quite different from the microbiota of nondiabetic adults. The content of Bifidobacteria is decreased, whereas Enterococci and Escherichia coli are increased significantly (R).
In T2DM patients, L. acidophilus and B. animalis increase good cholesterol (HDL-C) levels and decrease the LDL-C/HDL-C ratio (R). They further significantly decrease fasting blood glucose, and exert antioxidant properties (R).
A synbiotic containing L. acidophilus, L. casei, B. bifidum and inulin decreased fasting plasma glucose, blood insulin concentrations and increased insulin sensitivity in overweight diabetic patients with coronary heart disease. In addition, HLDL-cholesterol levels were increased (R).
L. acidophilus preserved insulin sensitivity in men with T2DM (R).
Soy milk containing L. plantarum has antioxidative properties and decreases DNA damage in patients with T2DM (R).
Diabetic patients who develop foot ulcers are at more risk of dying prematurely than those without the complication. B. subtilis shows antimicrobial activity against four diabetic foot ulcer bacterial pathogens (R).
B. animalis ssp. lactis reduces weight gain and fat mass, improves glucose tolerance (R), decreases fasting insulin and blood glucose, and significantly improves insulin tolerance in mice with diabetes (R).
B. bifidum decreased fasting blood glucose and insulin in diabetic rats (R).
B. bifidum can stabilize blood sugar, lower cholesterol levels in serum, and improve metabolic activity in mice (R).
L. brevis decreases glucose levels in diabetic rats (R).
L. gasseri decreases blood glucose and improves glucose sensitivity in diabetic mice (R).
Administration of L. casei and B. bifidum alone and in combination ameliorated hyperglycemia, dyslipidemia, and oxidative stress in diabetic rats (R).
L. casei significantly improved glucose intolerance, dyslipidemia, immune-regulatory properties, and oxidative stress in mice with T2D (R).
Treating diabetic mice with inviable L. salivarius reversed gut microbial imbalance, restored mucosal antibacterial protein and lessened endotoxin levels (R).
L. rhamnosus exerts an anti-diabetic effect in mice, with an anti-hyperglycemic effect in several rodent models. L. rhamnosus further improves glucose tolerance and enhances insulin sensitivity (R).
Treatment with L. plantarum favorably regulates blood glucose, hormones, and lipid metabolism in diabetic rats (R).
19) Probiotics Reduce Bad Cholesterol
Daily consumption yogurt containing L. acidophilus after each dinner contributes to a significant reduction in cholesterol (R). However, it was shown that L. acidophilus does not lower blood cholesterol in men and women with normal to borderline high cholesterol levels (R).
Buffalo milk yogurt and soymilk yogurt with B. longum decreased total cholesterol by 50%, LDL- cholesterol by 56%, and triglycerides by 51% (R).
In one study, L. reuteri reduced LDL cholesterol by 11.64%, reduced total cholesterol by 9.14%, non-HDL-cholesterol by 11.30% and apoB-100 by 8.41% (R). In another study, L. reuteri reduced LDL by 8.92% and total cholesterol by 4.81% (R).
6-week supplementation of L. salivarius along with fructooligosaccharide (FOS) significantly reduced total cholesterol, “bad” (LDL) cholesterol, and triglycerides (R).
B. longum reduced total cholesterol, particularly among subjects with moderate hypercholesterolemia (R).
L. fermentum modestly improved cholesterol in a clinical study (R).
In another study, a combination of bacteria strains more effectively reduced total cholesterol and liver cholesterol compared to individual bacteria strains (R).
B. animalis, B. bifidum and B. longum reduced total cholesterol and LDL-C in children with primary dyslipidemia (R).
Milk fermented with L. acidophilus and B. longum significantly reduced LDL cholesterol in hypercholesterolemic women (R).
In overweight subjects, the administration of capsules with Bifidobacteria, Lactobacilli, and S. thermophilus significantly improved lipid profiles, reducing total cholesterol (TC), triacylglycerols (TAG), and LDL-C levels (R).
See individual probiotic posts for more information and animal studies.
20) Probiotics Increase Good Cholesterol
Probiotics can increase high-density lipoprotein-cholesterol (HDL-C) (R).
In T2DM patients, L. acidophilus and B. animalis increase good cholesterol (HDL-C) levels (R).
A synbiotic containing L. acidophilus, L. casei, B. bifidum and inulin increased HDL-cholesterol in diabetic subjects (R).
A synbiotic shake containing L. acidophilus, B. bifidum and fructo-oligosaccharides significantly increased HDL-C in elderly people with diabetes (R).
6-week supplementation of L. salivarius along with fructooligosaccharide (FOS) significantly increased “good” (HDL) cholesterol in healthy young volunteers (R).
In overweight subjects, Bifidobacteria, Lactobacilli, and S. thermophilus significantly improved HDL-C (R).
B. coagulans increased good cholesterol in diabetic patients (R).
L. plantarum increased “good” (HDL) cholesterol in mice (R).
B. bifidum increased HDL in diabetic rats (R).
21) Probiotics Reduce Blood Pressure
Try: L. helveticus
Daily ingestion of the tablets containing powdered fermented milk with L. helveticus in subjects with high-normal blood pressure or mild hypertension reduces elevated blood pressure without any adverse effects (R).
Long-term treatment with L. helveticus-fermented milk reduces arterial stiffness in hypertensive subjects (R).
L. faecium and S. thermophilus reduced systolic BP in overweight and obese subjects (R).
Most probiotics are safe. However, care should be taken when administering probiotics to severely ill or immunocompromised patients. There have been rare incidents of sepsis, endocarditis, and liver abscess during the use of Lactobacilli; additionally, fungemia has been reported with the use of S. boulardii, primarily in patients with severe comorbidities (R).
The most common side effects of probiotics are constipation, flatulence, hiccups, nausea, infection, and rash (R).
Some probiotic bacteria can produce biogenic amines: L. brevis and L. lactis can produce tyramine and putrescine (R,R,R). S. thermophilus can produce low amounts of histamine and tyramine (R). L. reuteri is able to produce histamine (R,R).
In rare cases S. cerevisiae may induce allergic responses (R).
B. bifidum cell-surface biopolymers (BPs) can interact selectively with human serum thyroid peroxidase (TPO) and thyroglobulin (Tg) autoantibodies (anti-TPO and anti-Tg, respectively). There is a possibility that Bifidobacteria play a role in the pathogenesis of autoimmune thyroid diseases (ATD) in those with a genetic predisposition to ATD (R).
Probiotic products can be formulated as capsules, tablets, powders (which are regulated as a dietary supplement), and a food ingredient (e.g., yogurts, kefirs) (R).
L. acidophilus and B. longum can survive and adhere better to the gastric mucosa than S. thermophilus and B. infantis/adolescentis/bifidum (R).
L. acidophilus can survive at pH ≥3 after 3h, and L. rhamnosus can survive 4h incubation at pH 2.5. The viability of several strains of Bifidobacterium was maintained for ~3h in the pH range of 1.5–3.0. On the other hand, L. delbrueckii and S. thermophilus do not readily survive stomach acidity (R).
To overcome the inability of some probiotics to survive, microencapsulated or coated probiotic strains have been developed (R).
Furthermore, even though some viable probiotic strains do not survive gastric transit, their dead forms remain beneficial. These nonviable probiotics are now known as ‘paraprobiotics’ or ‘ghost probiotics’. Non-viable probiotics can ameliorate the anti-inflammatory response in rats with colitis, protect against Candida, or exert antiproliferative and proapoptotic effects on cancer cells (R).
Each probiotic species comes in many different strains. Some of the properties of each species may be strain-specific or vary between strains. You can find the information about each strain in the reference.
For technical information, check individual probiotic chapters:
- B. animalis (B. lactis)
- B. bifidum
- B. breve
- B. coagulans (L. sporogenes)
- B longum
- B. subtilis
- C. butyricum
- L. acidophilus
- L. brevis
- L. casei
- L. crispatus
- L. delbrueckii (L. bulgaricus, L. lactis)
- L. gasseri
- L. helveticus
- L. johnsonii
- L. lactis
- L. paracasei
- L. plantarum
- L. reuteri
- L. rhamnosus
- L. salivarius
- P. freudenreichii
- S. boulardii
- S. cerevisiae
- S. thermophilus
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