You may have heard the term probiotics floating around recently – especially among people trying to boost their health.
But, what are probiotics specifically? And, why are probiotics good for you?
Because make no mistake, they really are. In fact, probiotics are much more important to physical (and mental) health than most people realize.
The reason for this is related to an aspect of body that we often overlook, our gut.
The Significance of Gut Health
Collectively, the human body contains a large range of bacteria. Many of these bacterial species coexist with us and have no significant impacts on the body. But, some are in a mutualistic relationship, which means that the bacteria benefit, as do we. That pattern is especially common in the digestive tract.
In fact, the human gut contains more bacteria than other parts of the body, along with a greater diversity of bacteria.
For that matter, the gut itself is very important to health. Some estimates suggest that around 70% of the immune system is located in the gut (1), making it critical for fighting diseases and allergies.
Modern research increasingly shows that the composition of bacteria in our gut is critical to our health and wellbeing. Additionally, some behaviors and decisions around food can compromise the balance of bacteria, potentially increasing the risk of disease.
It’s clear that the distribution of gut flora is important – but what are the overall implications?
Well, the various species can play different roles. Some of them act to ferment dietary fiber, while others play a role in synthesizing vitamins and other useful compounds (3).
Having a good balance of gut bacteria has also been linked to a range of health benefits, which will be highlighted later on.
Causes of Compromised Gut Flora
There are also cases where a person’s gut flora may be significantly compromised and this can have dramatic impacts on health. Some theories suggest that this situation can increase disease risk and lower the function of the immune system as a whole.
Antibiotics are commonly used to treat a range of conditions (even though they are often overprescribed). However, the medication doesn’t discriminate between types of bacteria – so it harms the gut flora as well as unhealthy bacteria (4).
As a consequence, people who have been on antibiotics often have compromised gut bacteria and this often will not recover on its own (5).
Some other types of medication may have impacts on gut bacteria too, including NSAIDs.
This effect often isn't studied in depth, so we don't know which medications will and will not compromise your gut bacteria. But, if you're on any medication for a prolonged period of time, it may be worth taking steps to improve your gut flora, just in case.
Some of the food we eat may also harm the balance of bacteria in our gut, as can some health conditions. For example, diets high in refined sugars may be damaging to bacteria in the gut (6), as can a reliance on processed food (7,8,9).
Some research also suggests that diets high in fat and in sugar can cause damaging changes to gut bacteria (10,11). This type of change can result in lower cognitive flexibility, which refers to the ability to adjust to changes in a person’s situation.
There is growing evidence that artificial sweeteners may also harm gut bacteria (12) – and even just eating junk food periodically may cause damage, especially when this leads to overeating (13).
All of these patterns are concerning and mean that many people have lower levels of healthy bacteria than they need. But, most natural sweeteners don't appear to have the same effect.
There are other areas that may cause an unhealthy gut. The following areas are examples, although they haven't all been studied in depth.
- Increased hormone levels (such as during pregnancy or while on birth control)
- Stress, particularly if it is prolonged
- Mold or fungus, such as in a damp environment
- Toxic metal exposure
- Anything that slows digestion, such as chronic constipation or a digestive disorder
- Eating a narrow range of food
- Not getting enough prebiotics in your diet (these include many foods that promote short chain fatty acids)
- Too much alcohol
- Insufficient physical activity
- Lack of sleep
Promoting a good balance of bacteria in the gut is important for anyone and may offer significant health benefits. But, this pattern is particularly relevant for those who have lower-than-normal levels of gut bacteria.
A simple way around these issues would be to focus on a diet that is heavy in whole foods, where you are cooking most (or all) of your meals, rather than relying on processed alternatives.
If you also consume significant amounts of fruit and vegetables, you also boost your gut microbiome due to the presence of prebiotics, which are basically the food that your gut bacteria consume.
In many cases, you may also need to focus on getting probiotics into the diet, and we’ll talk about this area a little later on.
Other ways to help include getting more sleep, decreasing stress and exercising more. In other words, begin with areas that are important to physical health anyway.
Research and Directions
The health of our gut microbiome is still a fairly new field and research is mostly in its early stages.
To make matters more complicated, the gut microbiome is vast, containing many different species of bacteria, each of which may have its own implications for health (14). Furthermore, the distribution of gut bacteria varies from one person to the next, often dramatically (15).
As a result, we are still learning all of the implications of gut bacteria, along with ways to promote the best outcomes. Nevertheless, there is more than enough research to show that gut flora is critical to overall health.
What are Probiotics?
The field of probiotics strongly ties into the gut microbiota. According to the FAO and WHO, the term is defined as follows (16):
“live microorganisms which when administered in adequate amounts confer a health benefit on the host”
The concept is that probiotics help to increase the diversity and number of bacteria present in the gut, which then serves to boost health benefits overall.
Such an impact is particularly true for people whose gut flora has been compromised in any way, such as those who have been on antibiotics. Probiotics fall into two general categories.
Probiotics from Food
The first category is foods that provide some healthy bacteria. The is the key reason that fermented foods are good for you, as bacteria are a key component of the fermentation process. As a result, various fermented foods can be a powerful way to promote a good balance of bacteria in the gut. Plus, many of them also taste amazing.
The simplest example would be probiotic yogurt and many studies have shown this yogurt can help promote positive digestion outcomes (17,18,19). For that matter, yogurt is a common choice for probiotic research and there are many healthy types to choose from.
However, if you do go with yogurt, make sure you pick a brand that actually contains healthy bacteria – as that isn’t always the case. Additionally, it’s important to pay attention to the species of bacteria, as different products will vary in what they include and there may be multiple species present.
Another popular option is kombucha, which is typically a type of fermented tea (although it can also be made with coffee). Kombucha is also very popular because you can make it at home, such as with this kit.
There are also many guides for making kombucha. For example, Wellness Mama talks about the benefits of kombucha and how to make it for yourself. The site Whole Natural Life offers details for another type of fermented drink - kefir.
There are many other options too. Sauerkraut and kimchi contain probiotics, along with any pickled foods.
The other category for probiotics is supplements. Like with yogurt, probiotic supplements often contain multiple types of healthy bacteria and the strains vary from one brand to the next.
This type of supplement can come in many forms, such as a powder or a pill. One example is this product from Dr. Mercola, which also acts as a good starting point for supplementing with probiotics.
As a general rule, it's better to get nutrients from food than from supplements. But, probiotic supplements do have some important advantages.
- You know you're getting probiotics. Fermented foods can be a good source of probiotics but they won't always contain bacteria (especially as some commercial products are pasteurized). Even when they do, there's no way to know how much. Probiotic supplements are designed to provide a certain amount of probiotics.
- You get specific strains. With supplements, you know precisely what strains you're going to get. This is important, as individual strains have been linked to different health benefits. With a supplement, you can match the strain to what you're trying to achieve. This isn't possible with fermented foods.
- You can compare doses. Probiotics supplements also tell you the amount of probiotics present. They use the measure CFU, which stands for Colony-Forming Units. This makes it easy to work out which products are best.
- They have a longer shelf life. Most of the time, probiotic supplements will last longer than fermented foods. They're often more practical as well.
If nothing else, probiotic supplements can be a good way to recover your gut health. You can then turn to probiotic and prebiotic foods to help maintain the bacteria in your gut.
Why Are Probiotics Good for You?
The simple answer about probiotics and health comes back to the topic of gut bacteria. Ideally, probiotics help increase positive bacteria in the gut, potentially resulting in health benefits overall.
As with gut health itself, research into this field is still ongoing. But, there is considerable evidence that probiotics can help to improve health. For example:
- Probiotic use is particularly relevant for diabetes, as it has been linked to better glycemic control (20,21,22) and improvements in HbA1c levels (23).
- Probiotics have also been linked to other health benefits, such as fighting migraine headaches (24).
- Taking probiotics at the same time as antibiotics may also help to prevent and treat the diarrhea that antibiotics commonly cause (25).
- Likewise, probiotics can help with conditions like inflammatory bowel disease (26,27) and may play a role in fighting cancer (28).
However, not all research has agreed. For example, one study pointed out that findings on anti-inflammatory, antioxidant and HbA1c effects have been inconsistent across studies and that more research is needed (29).
There are also many other potential interactions that have yet to be studied in any detail.
Even though we don’t know all of the mechanisms involved, these patterns strongly suggest that probiotics can help to promote health. Plus, many probiotics offer benefits of their own, especially the options that come from food.
Probiotics and Mental Health
There is increasing interest in the link between probiotics, gut health and mental illness. For example, conditions that involve anxiety and depression have been associated with more permeability in the gut (30).
Research has also shown differences in microbiota composition between people with major depressive disorder and those who do not (31), although cause and effect has not yet been proven.
One animal study even showed that transplanting ‘depression microbiota’ tended to result in depression-like symptoms, while the reverse did not (32). This pattern strongly suggests that gut bacteria may directly influence depression symptoms.
This isn’t especially surprising, as there is an association between what people eat and their brain function, which is particularly relevant for mental illness.
Probiotics have also been found to significantly affect interactions between the gut and the brain (33). This could also be the reason that probiotics may help with migraines (34,35), especially as there is a connection between migraines and gastrointestinal disorders (36).
With all this in mind, there is the potential for probiotics to help reduce some symptoms of depression. Some research with supplements supports this theory, although more evidence is needed (37,38,39,40).
Which Probiotics Should You Use?
With research ongoing, it isn’t clear what the absolute best choices for probiotics are.
In fact, many of the meta-analyses into the field simply considered any type of probiotic addition, regardless of the type of bacteria and whether it was food or supplement-based.
Furthermore, it’s likely that the impacts of specific probiotics will vary depending on the individual person and the state of their gut microbiome (41).
With this in mind, one of the best answers may simply be to vary the types of bacteria that you take through probiotics. After all, the gut microbiome is diverse and the various bacteria have different roles. As a result, consuming different types of bacteria through probiotics is likely to offer the best overall outcomes.
To do this in practice, you could choose to increase the amount of fermented food in your diet, while also using a using a probiotic.
It may also be worth paying close attention to the way that your body responds. After all, we do have different gut flora from one another. This means that some people may see benefits from a particular product or strain of bacteria, while others may not.
Likewise, some people are likely to see more benefits than others, especially if their gut microbiome was compromised in some way.
One final approach may be to try and find specific bacteria, as some strains have been studied more than others. For example, the site Dr. David Williams highlights five different bacterial strains that he considered to be powerful, one of which is Lactobacillus acidophilus.
Choosing bacteria in this way could be beneficial, especially if the research lines up with a particular health condition that you have. However, do be aware that the research is still incomplete and many strains have not been studied in depth.
As a result, the most powerful approach is still to vary the bacteria and not stick to a single strain.
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