We share our bodies with our gut microbes. They can make us thin or fat, healthy or sick, happy or depressed. That is why many researchers and doctors believe that is important to keep our microbiome well balanced. Read on to learn about the many factors that can affect the human gut flora.<\/p>\n
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Our gut microbiome is extremely important. The bacteria we carry have various roles in our bodies and affect our lives in a multitude of ways. That is why it’s important to keep them in balance. In this post, we review the various factors that have an impact on our gut bacteria<\/a>.<\/p>\n To learn more about the human gut microbiome and how it shapes our bodies and our minds, check out this post:<\/p>\n Gut Microbiome: 33 Ways Gut Bacteria Affect Your Body and Mind<\/a><\/p>\n What we eat<\/strong> has a great effect on our<\/strong> gut bacteria<\/strong>. If the good bacteria species in foods or supplements do not have the appropriate fuels or conditions to grow in your gut, they may not colonize. Therefore, your diet has a larger effect on the<\/strong> gut microbiota<\/strong><\/a> composition than<\/strong> probiotic<\/strong><\/a> supplementation <\/strong>[R<\/a>].<\/p>\n Dietary changes can account for up to 30 – 60% of gut microbiota changes, whereas genes account for no more than 12% [R<\/a>, R<\/a>].<\/p>\n People who eat a lot of animal fat or protein have more Bacteroides<\/em>, while those who eat a lot of carbohydrates have more Prevotella<\/em>. Firmicutes are associated with fiber-rich diets [R<\/a>, R<\/a>].<\/p>\n The western diet is high in red meat, animal fat, and sugar and low in fiber. This tends to promote the growth of Bacteroides <\/em>[R<\/a>].<\/p>\n Prevotella <\/em>are the most abundant bacteria in most vegetarians [R<\/a>].<\/p>\n Short-term dietary modifications change microbiota rapidly but also reversibly. <\/strong>Long-term dietary change, however, can cause irreversible alterations to gut microbiota [R<\/a>].<\/p>\n One study investigated what would happen when people ate either plant- or animal-based diets exclusively for 5 days. Their bacteria changed within the first day. However, bacteria also reverted to the original state 2 days after the diet was over [R<\/a>, R<\/a>].<\/p>\n Long-term consumption of a Mediterranean diet<\/strong> increased<\/strong> butyrate<\/strong><\/a> producers<\/strong> [R<\/a>].<\/p>\n Prebiotics are non-digestible plant fibers (complex carbohydrates) that nourish the gut flora. They [R<\/a>]:<\/p>\n Prebiotics include oligo- and polysaccharides, inulin<\/a>, resistant starch<\/a>, and pectin<\/a>.<\/p>\n Prebiotics promote the growth of beneficial bacteria<\/strong>, such as Bifidobacteria<\/em> and Lactobacilli <\/em>in humans [R<\/a>, R<\/a>, R<\/a>, R<\/a>, R<\/a>].<\/p>\n They also increase butyrate-producing bacteria [R<\/a>, R<\/a>].<\/p>\n In 19 subjects, fiber increased overall microbiota richness and stability [R<\/a>].<\/p>\n Probiotics can increase the levels of ‘good bacteria’ such as Lactobacilli <\/em>and Bifidobacteria <\/em>in the gut while decreasing the levels of potentially harmful microbes [R<\/a>, R<\/a>, R<\/a>, R<\/a>, R<\/a>, R<\/a>, R<\/a>, R<\/a>, R<\/a>, R<\/a>, R<\/a>, R<\/a>, R<\/a>, R<\/a>].<\/p>\n Probiotics<\/a> also increase SCFA levels (such as butyrate) [R<\/a>, R<\/a>, R<\/a>, R<\/a>].<\/p>\n They also help restore gut microbiota after a course of antibiotics or illness [R<\/a>, R<\/a>].<\/p>\n Stress<\/a> can disturb gut microbiota, and this can, in turn, cause various disorders and diseases.<\/p>\n A study addressed the effects of stress on pregnancy (measured as self-reported stress, elevated cortisol<\/a> levels or both). Of the 56 infants observed in the study, those born to mothers who were stressed during pregnancy had disturbed gut microbiota. They had more harmful bacteria, and lower levels of ‘good bacteria’, such as lactic acid<\/a> bacteria and Bifidobacteria. They were also more prone to gut disorders and allergic reactions [R<\/a>].<\/p>\n A similar situation was found in animals, where stress in pregnancy altered the gut microbiota of the offspring [R<\/a>, R<\/a>, R<\/a>].<\/p>\n Stress negatively changed gut microbiota in mice. They end up having increased intestinal permeability<\/a> and became prone to drug-induced gut injury [R<\/a>].<\/p>\n Exercise<\/a> may increase the number of ‘good’ bacteria and enrich gut microbial diversity [R<\/a>].<\/p>\n A study showed that elite rugby players (40 subjects) had richer gut microbiota compared to carefully chosen non-athletic controls (46 subjects). In particular, there was a greater diversity of Firmicutes <\/em>(including the beneficial Faecalibacterium prausnitzii<\/em>) [R<\/a>].<\/p>\n Another study compared 40 active and sedentary women. Active women had more health-promoting bacteria <\/strong>(including F. prausnitzii<\/em>, Roseburia hominis,<\/em> and Akkermansia muciniphila<\/em>) [R<\/a>].<\/p>\n When a study compared 39 healthy subjects with various degrees of fitness, fit individuals had more butyrate-producing bacteria<\/strong> [R<\/a>].<\/p>\n A high abundance of Prevotella (\u22652.5%) was associated with the duration of exercise during an average week in 33 cyclists [R<\/a>].<\/p>\n Exercise also improves gut microbiota in animals [R<\/a>, R<\/a>].<\/p>\n Interestingly, early-life exercise in rats was more beneficial compared to exercise in adulthood [R<\/a>].<\/p>\n While low-intensity exercise has been found to be beneficial, some researchers believe that endurance exercise may have a negative effect [R<\/a>].<\/p>\n Military-type training had a negative impact on gut microbiota and increased gut inflammation in 73 young soldiers [R<\/a>].<\/p>\n In mice with IBD<\/a>, voluntary wheel running improved symptoms. Forced treadmill running, on the other hand, worsened gut inflammation [R<\/a>].<\/p>\n Lack of sleep<\/a> and low sleep quality disturb gut microbiota.<\/p>\n Nine people had increased Firmicutes<\/em>\/Bacteroidetes<\/em> ratio after two days of partial sleep deprivation.<\/strong> Sleep deprivation caused a shift in gut bacteria associated with metabolic disturbances (that can lead to metabolic syndrome and diabetes) [R<\/a>].<\/p>\n Chronic sleep fragmentation reversibly altered gut bacteria in mice (by decreasing beneficial Lactobacilli) [R<\/a>].<\/p>\n Dietary prebiotics improved both gut microbiota and sleep quality in rats [R<\/a>].<\/p>\n Shift work increases the risk of obesity<\/a>, metabolic syndrome, and type 2 diabetes, and perturbations in gut bacteria are one of the main suspects in this relationship [R<\/a>].<\/p>\n Jet lag may disturb the daily fluctuations of<\/strong> gut<\/strong> microbiota, causing a microbial imbalance also known as dysbiosis<\/strong>. Germ-free mice that received gut bacteria from jet-lagged mice developed glucose<\/a> intolerance and obesity [R<\/a>].<\/p>\n Antibiotics, proton pump inhibitors, antidepressants, statins, and other commonly used drugs may alter microbiota in specific ways. As a consequence, commonly used drugs could affect how the gut microbiota resist infection, promote or decrease gut inflammation, or change the host’s metabolism [R<\/a>].<\/p>\n Antibiotics<\/strong> are used to treat or prevent infection. However, they can cause unintended damage by depleting beneficial gut bacteria<\/strong> [R<\/a>].<\/p>\n Antibiotics can dramatically decrease the richness of the gut community [R<\/a>].<\/p>\n In some cases, after prolonged antibiotic treatment, full restoration of the gut microbiota is no longer possible [R<\/a>].<\/p>\n A 7-day therapy with clindamycin<\/a>, which has a strong and broad activity, decreased the diversity of Bacteroides<\/em> in 4 subjects, compared to another 4 people who didn\u2019t take the drug. The diversity was not restored to its original level even two years after therapy [R<\/a>].<\/p>\n These effects can also be transferred to the next generation. In a study of 606 infants, depleted microbiota was found in infants born to mothers treated with antibiotics [R<\/a>].<\/p>\n Furthermore, certain <\/strong>‘bad bacteria<\/strong>‘ may take advantage of the disturbance caused by antibiotics<\/strong> and multiply<\/strong> [R<\/a>].<\/p>\n To minimize the risk of gut dysbiosis, it is best to use narrow-spectrum antibiotics whenever possible [R<\/a>].<\/p>\n Finally, in some conditions where gut microbiota is already disturbed<\/strong>, antibiotics can actually help<\/strong>. They can restore gut microbial balance by decreasing <\/strong>\u2018bad bacteria<\/strong>\u2019. For example, in two studies of a total of 211 IBS<\/a> patients, rifampin resolved the overgrowth of bad bacteria [R<\/a>, R<\/a>].<\/p>\n The overuse of PPIs shifts the gut microbiome towards a less healthy state<\/strong>. It may increase the risk of gut infections. PPIs also seems to favor Streptococcal growth – these are harmful bacteria that may cause ulcers [R<\/a>].<\/p>\n In a study of 1815 individuals, 211 PPI users had lower bacterial diversity and 20% of their bacteria was significantly altered compared to non-users [R<\/a>].<\/p>\n<\/a>Factors that Affect the Gut Microbiome<\/strong><\/span><\/h2>\n
<\/a>1) Diet<\/strong><\/span><\/h3>\n
<\/a>Prebiotics: Plant Fiber and Resistant Starch<\/strong><\/h4>\n
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<\/a>Probiotics<\/strong><\/h4>\n
<\/a>Foods that May Improve Gut Microbiota<\/strong><\/h4>\n
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<\/a>Foods that May Have Negative Effects on Gut Bacteria<\/strong><\/h4>\n
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<\/a>Foods with Complex Effects on Gut Bacteria<\/strong><\/h4>\n
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<\/a>2) Stress<\/strong><\/span><\/h3>\n
<\/a>3) Exercise<\/strong><\/span><\/h3>\n
<\/a>4) Sleep<\/strong><\/span><\/h3>\n
<\/a>Jet Lag<\/h4>\n
<\/a>5) Medications<\/strong><\/span><\/h3>\n
<\/a>Antibiotics<\/strong><\/h4>\n
<\/a>Proton Pump Inhibitors (PPIs)<\/strong><\/h4>\n
<\/a>NSAIDs<\/strong><\/h4>\n