By Cat, Dec 2006 and updated Mar 2008 (Photo, right, from Wikimedia Commons)
- See also: 1. Whole Foods (About) Menu; 2. Culturing, Curing & Fermentation (Menu); 3. Cultured Dairy (Menu);
- Includes: 1. Bugs in the gut; 2. Foods to provide & feed probiotics; 3. Supplements: Probiotics & Prebiotics
See also an excellent article by Gary Null (The link is no longer valid; I’ve contacted Mr. Null for a copy.
For much of the 20th century, American medicine has basically ignored promoting the health of the gut (and reluctantly attempted to treat it when it was seriously ill). Our diet is full of processed foods that are devoid of good bacteria and the whole foods that feed them. As a result, serious health issues like type-2 diabetes, heart disease and cancer are out of hand. Times are changing, however, and now much more attention is paid to our gut, which is, after all, our primitive brain.
A healthy gut depends on healthy colonies of native gut flora. When these are in proper balance, your system is said to be in a state of homeostasis, or “eubiosis.” When it is out of balance, it is said to be in a state of ‘dysbiosis.’ The most common condition causing dysbiosis is Candida overgrowth, or Candidiasis (links to my old site). (For more on this, see also Gut Health (links to my old site).
Bugs in the Gut
Our digestive tract — or gut — is colonized by many microscopic species, or flora, including bacteria and yeast. Each individual has a unique combination of microbes, very much like a fingerprint. However, there are a few species that most of us have in common, which are discussed below.
In a healthy individual, these “bugs” live with us in a balanced, symbiotic relationship (beneficial to both). Some help us to digest protein; others to digest carbohydrates (sugars, starches and fiber). Most contribute vital nutrients including vitamins to our gut. They help us maintain our gut with proper pH (level of acidity), which promotes absorption and assimilation of nutrients from our digested food. And most even help us maintain a healthy immune system (remember, over 80% of our immune system is in the gut!). This microflora can be divided into the following categories
- ‘probiotic‘ promote life. They are essential not only for proper gut function, but to overall health, and should comprise 85% of all bugs in a healthy gut. They provide essential vitamins, make minerals more bio-available, maintain proper pH of the gut, and provide immune protection;
- ‘putrefactive‘ promote decay (such as in compost); in this role, they help to decay dead tissue and waste products in the gut, so they can be eliminated. They, too, are essential to proper gut function, but may lead to health issues if their numbers exceed a normal balance. They should comprise 15% of all the bugs in a healthy gut;
- ‘pathogenic ‘are disease causing, and generally are not native to a healthy gut, but can invade our gut when it is out of balance. They have no known benefit for health; indeed, they can cause a diseased state. Within this category are bugs such as E. coli, of which native strains are beneficial putrefactive bacteria, but non-native strains may be pathogenic.
The proper balance of gut flora is 85% probiotic and 15% putrefactive; this balance will ensure a healthy gut that can keep pathogenic microbes at bay.
The Role of Probiotic Lacto & Bifido Bacteria
These are among the most common in our gut. Most break down sugars and starches and to produce lactic acid. Other species ferment inulin fiber to produce short-chain fatty acids (acetic, propionic, butyric acids), which make their environment slightly acidic, which in turn makes it difficult for alkaline-loving bad bacteria, candida and parasites to proliferate.
Lactobacteria such as L. acidophilus are found primarily in the small intestine; they are present in foods such asonions, tomatoes, bananas, garlic, and raw honey (26). They are used to culture products such as yogurt, cottage cheese, kefir, old-fashioned sauerkraut, and kimchi. These probiotic bacteria (3, 8, 20):
- secrete enzymes which aid in digestion;
- help us assimilate vitamins, proteins, fats, and carbs from the gut;
- produce B-Vitamins, especially thiamine (B1), riboflavin (B2), and nicotinic acid (B3); may also be involved in synthesis of biotin, folic acid and B6;
- synthesize vitamin K (responsible for clotting of blood);
- synthesize assorted amino acids;
- produce specific antibacterial compounds that inhibit reproduction of harmful bacteria;
- produce organic acids (lactic, acetic and butyric), to lower pH (more acidic) and reduce oxidation;
- deconjugate bile acids so that the bile can be re-used;
- play an extremely important role in supporting the immune system. They are our first defense against invaders that enter our bodies through the digestive tract.
Bifidobacteria such as B. lactis and B. longum are found primarily in the large intestine (colon). They are also used to culture yogurt, and have many benefits in common with lactobacteria. In addition, they (9, 20):
- resist the action of bile acids and survive passage through the GI tract;
- inhibit many pathogenic organisms including Salmonella, Shigella, Clostridium, Bacillus cereus, Staphylococcus aureus, Candida albicans, and Campylobacter jejuni;
- believed to have anti-carcinogenic and anti-cholesterolemic properties (various studies in the 1980s);
- assist in detoxification of the liver, and can be important in re-establishing normal flora that are otherwise disturbed by chronic cirrhosis of the liver, by reducing ammonia and free phenols in the liver.
See also Jim Trade article ‘Probiotics: An Emerging Alternative‘ (27) for more.
Common Probiotic Bacteria
The following list includes a few common native probiotic bacteria that are commonly used in probiotic supplements (13), but are also common in raw or fermented foods. Note that not all strains of each species are native to the human gut, and may not colonize in the gut, but will reside their for up to 2 weeks and still provide benefit.
These bacteria reside together in colonies, so that each species provides support for the other species in the colony. If one species is decimated, it is likely the entire colony will die.
- Bifidobacterium bifidum produces acetic and lactic acid, which lower the pH of the gut (a good thing). It is found in both the large intestine and the vaginal tract, where it plays a role in preventing colonization of invading microorganisms (bad bugs), and enhances assimilation of many minerals such as iron, calcium, magnesium and zinc. (13)
- Bifidobacterium longum converts sugars to lactic acid. It is found primarily in the large intestine, where it plays a role in preventing colonization of invading microorganisms (bad bugs). (13, 29)
- Enterococcus faecium has strong activity against invading pathogens (bad bugs), but only transiently colonizes the gut. However, certain strains of this bacteria could be pathogenic. (13)
- Lactobacillus acidophilus not only produces lactic acid, but also natural antibiotics, making it a very important part of the immune system. It is found primarily in the small intestine, but also in the wall of the vagina, cervix and urethera. It prevents pathogenic organisms from multiplying and colonizing. Food sources include and can be found in foods such as onions, tomatoes, bananas, garlic, and raw honey. (13, 26)
- Lactobacillus casei is closely related to L. rhamnosus and L. acidophilus. It converts sugars to lactic acid, and also produces bacteriocins (compounds that inhhibit the growth of pathogenic bacteria in the small intestine. (13)
- Lactobaccilus gasseri is another member of the acidophilus family, and is “the major homofermentative lactobacillus species that occupies the human GI tract.” (24) (Homofermentative means that they produce only lactic acid, as opposed to heterofermentative which can also produce alcohol and acetic acid from sugars). It is known to be anti-inflammatory in the gut (25). Recent research (2010) indicates that it is important in regulating adiposity (storage of fats in adipose tissue), so could be important for those who want to lose weight (22, 23). (13)
- Lactobacillus rhamnosus converts sugars to lactic acid. At one time it was considered a subspecies of L. casei, but has now been determined to be a separate species. It is found in the small intestine and the vagina, but has also been known to colonize in the large intestine. It protects the gut against the invasion of pathogens such as steptococci and clostridia. It creates anaerobic conditions in the large intestine, which favor the implantation of bifidobacteria. It has also been shown to favorably affect lactose intolerance. (13, 23)
- Lactobacillus sporogenes is unique among the Lactobacilli, in that it is in the form of spores, and thus can easily survive transit through the highly acidic stomach, and exposure to the alkaline bile salts. It has been shown to colonize in the human gut; however, the colonies may not last after supplementation with the probiotic is discontinued (this is a common problem with many probiotic supplements). (14)
Refer also to Summary of Probiotic Strains (28).
Foods to provide and feed probiotics
Our native gut microbe colonies not only support us, but also rely on us to support them; it’s a symbiotic relationship. Eating foods rich in probiotics helps to keep their environment acidic and supportive; eating foods that feed the colonies keeps them strong and growing. And in return, they fight to keep us free of parasites and pathogenic microbes by strengthening our immune system, they help us digest our food and provide additional nutrients critical to our health.
Foods rich in probiotics
Perhaps the most important foods we can consume are those rich in life-supporting microbes or ‘probiotics,’ which keep our native microbe colonies in good health so that we are in good health.
Raw milk from dairy animals is especially nutritious and rich in probiotics, as it is the first food for their babies, and is needed to build up their natural immunities to disease. These good bugs will colonize in the dairy infant, and many believe they will also colonize in human infants and adults.
Cultured milk products: Culturing milk involves the action of probiotics on the proteins and sugar in the milk:
- Yogurt is perhaps the most common cultured milk product in the US. To be yogurt, it must include S. thermophilus and L. bulgaricus. S. thermophilus is what requires culturing at 110 – 116F (above room temperature); L. bulgaricu gives yogurt its sweet-tart flavor. Additional bacteria such as L. acidophilus or Bifidus may also be added. The bacteria in yogurt produce the R-form of lactic acid.
- Kefir is a cultured or fermented beverage traditionally made from milk, and using kefir grains comprised of bacteria and yeast. These are from four genus groups: Lactibacilli, Streptococci-Lactococci, Acetobacter, and Yeasts. (Refer to Dom’s Kefir website (16) for a complete list of species). Kefir’s bacteria produce the L-form of lactic acid, which is more bio-available than the R-form found in most yogurt. The beneficial yeasts in kefir “dominate, control and eliminate destructive pathogenic yeasts [such as candida], and help the body to resist… [intestinal] parasites.” (15)
- Other cultured milk products rich in probiotics include: Cottage Cheese, Crème Fraiche, Piima, Villi & FilMjolk, and Sour Cream (Butter & Buttermilk)
Interesting idea: Dom’s Kefir website includes a recipe for ‘Kefir Ice Cream,’ which I include have copied as Chocolate-Nut Kefir Gelato.
Raw Fruits and Veggies: Fruits and vegetables grown in good healthy soil (not contaminated by chemical fertilizers, pesticides, herbicides, nor insecticides) are rich in probiotic microbes. This is because like us humans, the plants also need probiotics to maintain optimum health. However, it is important to eat them raw (if you want the good bugs), as the heat of cooking would kill them.
Lacto-Fermented Condiments and Beverages: Sauerkraut is perhaps the best known of lacto-condiments, but many commercial brands ferment the cabbage with vinegar instead of lactic acid. So look for those that indicate ‘lacto-fermented,’ or make your own (Refer to Culturing, Curing and Fermentation Menu for Lacto-condiments and beverages recipes).
Other lacto-fermented condiments & beverages include:
- Brined Greek and other Mediterranean olives (California olives are not typically lacto-fermented); brined olives are immersed in the salty brine (as opposed to canned olives sold in sealed jars or cans);
- Kimche (Korean sauerkraut)
- Pickles: most commercial varieties are pickled in vinegar, but some gourmet varieties are lacto-fermented. You can also make your own.
- Chutneys: most of these are still lacto-cured, and it is easy to make your own
- Real ginger ale, rootbeer, and orangina are traditional lacto-fermented beverages that you can make at home. Most commercial varieties are not fermented at all.
- Kefir Sodas: Lemonade, ginger ale, cream soda
- Kvass, made from grains or beets, is an ancient health-promoting lacto-fermented beverage.
Foods to feed and promote growth of probiotic colonies
In healthy individuals, the overgrowth of candida yeast and infection by pathogens is kept in check by probiotic (pro-life) bacteria. When the beneficial lacto-bacteria are decimated by broad spectrum antibiotics, or by depriving them of the lactose and fiber they need to survive, candida and pathogens are given free rein. Prior to the widespread and mandatory pasteurization of milk and other dairy products, this was rarely a problem.
Add foods naturally rich in probiotics:
- cultured dairy products: yogurt, kefir, buttermmilk, liquid whey, creme fraiche, cream cheese, cottage cheese;
- pickled vegetables (in whey): kimchi, sauerkraut, greek olives, pickled beets.
- fermented beverages (not pasteurized): kombucha, rejuvelac, kvass, beer, root beer, dahi, lassi (sweet or salty).
Feed your probiotics with prebiotics: bifido-bacteria thrive on inulin (or supplemental FOS); lacto-bacteria thrive on whey and lactose.
- Inulin is present plant sources such as roots (5) and certain fruits. Refer to Inulin (links to old site) for more. See also Breaking the Vicious Cycle article on inulin (30). Inulin-rich foods:
- Dandelion root
- Sweet Potatoes
- Wild Yam
- Jerusalem artichokes
- Agave (avoid agave nectar, as the inulin has been broken down into free fructose)
- Green bananas
- Whey is one of the protein fractions of milk. Common healthful sources of whey are cultured milk products. Commercial whey is not recommended, because the process used to dry the whey into a powder denatures the proteins in the whey fraction; additionally, the lactose in whey is usually removed.
Other ways to encourage growth of existing native colonies
- Create a friendly environment for them (proper pH);
- Eat sprouted seeds: Sprout your grains and seeds before consuming (rice & flax seeds are exceptions); this helps to increase the acidity of your gut by absorbing alkaline minerals; refer to Gut Health (links to old site) to learn more;
- Avoid sugar and sugary foods which feed the competitors (bad bacteria, yeasts and parasites).
- Cut back on highly refined grain products which are sources of simple sugars and promote candida growth;
- Avoid junk and processed food;
- Avoid antibiotics;
- Eat lots of fresh fruits & veggies, to facilitate proper balance of gut flora;
- Drink plenty of water, to flush out toxins that promote bad bugs or kill good bugs.
- garynull.com/documents/Arthritis/Friendly_Bacteria.htm (no longer valid url)
- articles.mercola.com/sites/articles/archive/2009/10/31/Friendly-Bacteria-Blunt-AntiNutrient-Action.aspx and www.ncbi.nlm.nih.gov/pubmed/19817458?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum
- newscientist.com/article/mg20527536.300-for-a-trimmer-figure-add-an-extra-helping-of-gut-bugs.html and European Journal of Clinical Nutrition June 2010; 64(6):636-43
- SF Gate: healthyeating.sfgate.com/bifidobacterium-lactis-benefits-3870.html and healthyeating.sfgate.com/sources-acidophilus-9578.html
- Jim Trade article ‘Probiotics: An Emerging Alternative’ articles.jimtrade.com/1/158.htm
- Summary of Probiotic Strains: phototour.minneapolis.mn.us/candida/summary.html
- Breaking the Vicious Cycle, on Inulin: breakingtheviciouscycle.info/knowledge_base/kb/inulin.htm