Do you peel lemons before tossing them into your morning smoothie? How about beets, cucumbers, or kiwis?
The peelings provide added nutrition; no reason to toss them out. I’m also a big fan of fiber, so I don’t peel most fruits or veggies. Plus, my personal entourage of microbial critters, the hundreds of thousands of bacterial species (gut flora, AKA microbiome) that call me home, thrive on this diet as well. Yes, my body is a temple, complete with a bazillion little symbiotic worshipers.
At least that’s the idea. We need a healthy, diverse, and thriving microbiome as part of our internal ecology. That helps keep the immune system strong, autoimmunity in check, and may reduce the risk of some forms of cancer, especially those associated with the GI tract. We’re bombarded today with chemicals our grandparents weren’t exposed to. Many of these toxic substances (pro-carcinogens) become genotoxic (mess up our DNA) upon metabolic activation by our gut bacteria.
Our world is toxic. We eat, drink, breath, and expose ourselves to harmful substances on a daily basis, many of which are in our food supply. Research indicates that a large percentage of known carcinogens require enzymatic activity to trigger malignancy. The bacterial composition of the gut microbiome (good bugs vs bad bugs) and the metabolic byproducts from all those critters can either protect us or do us in.
The idea is to encourage the good bugs to flourish. It’s also important to keep things moving along, if you know what I mean. A plant-based, high-fiber diet not only provides nourishment for our friendly bacteria, it also helps fight disease and prevents us from being full of poo.
The role of the gut microbiome is a hot research topic these days, and although the findings are intriguing, they can also be confusing. Or weird, especially when you throw cootie genomics into the mix. It’s not just our DNA floating around in the gene pool, it’s also the genetic elements of our personal collection of microbes. We’re one big complex ecosystem. Hopefully our microbiome is living in harmony with the rest of us. Food choices, pre- and pro-biotics, and how much fiber we consume can shift the bacterial composition to either enhance our well-being or encourage disease. Here are a few details.
Microbiome: the interaction of all the microscopic organisms, including their genomes, in one specific environment.
* In this post, I’m focused on the human gut microbiome. If you’re interested in the skin microbiome and you’re not germaphobic, check out this article on women’s flat track roller derby in which the skin microbiome of individual contestants was analyzed and matched to team membership. Each team had its own specific microbe community. Not only did they have team colors and team mascots, they had team cooties. Very cool. And weird.
Prebiotics: Nondigestible food ingredients (fiber) that encourage the growth of beneficial bacteria. Prebiotics are food for microbes. Feed your microbes well.
* Gluten-free sources of foods containing prebiotic fiber include Jerusalem artichoke, jicama, asparagus, banana, dandelion greens, onions, leeks, garlic, raw oats (make sure they’re certified gluten-free), chicory root, and yacon. Unrefined wheat and barley are also good sources, but those foods are off limits for those of us with gluten intolerance.
Probiotics: live microbes that provide health benefits to the host (you) by augmenting beneficial intestinal bacteria.
* Probiotics can be found in supplement form. I don’t take supplements, so I try to get my dose of probiotics from fermented foods like miso, sauerkraut, yogurt, and kefir.
Fiber: The nonstarch polysaccharides found in plant foods that are not broken down by human digestive enzymes, although some (prebiotics) are digested by GI tract bacteria. Fiber is often categorized as soluble or insoluble.
Insoluble fibers are called “bulking agents.” They help keep us regular (poo-wise). This is the fiber most people refer to when they talk about constipation. It literally sweeps out the GI tract, which is a good thing. Remember the Elvis story?
Soluble fiber helps that process, but it also has therapeutic effects. Soluble fiber delays the absorption of glucose (insulin response), helps us feel full, and decreases cholesterol levels. There’s even research suggesting soluble fiber may help reduce blood pressure and improve the absorption of minerals.
That last part is especially interesting. Some people avoid grains and legumes because of the phytic acid (phytate) content. Phytic acid isn’t classified as fiber, but is common in fiber-rich foods. It’s a non-nutrient, found in the husk of grains, legumes, and seeds. It can bind with certain minerals (zinc, iron, calcium, magnesium) and decrease their absorption.
But — researchers have also demonstrated that rats absorb more calcium, iron, and magnesium when fed a diet rich in soluble fiber, which is found in those same plants. We’re not rats, but these are interesting findings. Another article suggested that when soluble fiber ferments in the colon, it enhances the absorption of minerals. We eat the plants that contain both phytic acid and soluble fiber and what happens? Beats me, I’m not a biochemist, but the type of fiber appears to be important when it comes to mineral absorption. Soluble fiber that promotes intestinal fermentation and an increase in beneficial bacteria has a positive effect on mineral bioavailability. It’s a convoluted puzzle with lots of variables and depending on what you want to prove, you could cherry-pick data from either side to make your case. Having said that, I’m not convinced phytic acid is anything to worry about, especially if your diet is based on whole foods (lots of plants) rich in micronutrients and fiber.
Soluble fiber in the form of prebiotics is the stuff our gut microbes call dinner. The names don’t really matter, but if you’re interested — inulin, fructooligosaccharides (FOS), arabinooligosaccharides (AOS), and to some degree, pectin, are soluble fibers with prebiotic properties. As mentioned above, they help increase good bacteria at the expense of bad bacteria.
Here’s where it gets even more interesting. You’re fascinated by all this, right?
You’ve probably heard of leaky gut (intestinal permeability), especially if you have celiac disease, gluten sensitivity, Crohn’s disease, IBS, or any other autoimmune or GI related condition. We don’t know all the causes of leaky gut, but one thing is clear. The “Standard American Diet” (processed food, low fiber, high animal product diet) compromises food transit and waste elimination.
In other words, if stuff doesn’t move along at the right speed, you end with a bumper-to-bumper traffic jam.
When that happens, it alters nutrient availability to good gut bacteria and stimulates an overgrowth of bad gut bacteria. The bad bugs start partying, produce icky byproducts, and our intestinal cells take a beating. That abnormal balance alters gut permeability and allows funky stuff to slip through the cracks and be absorbed into the bloodstream. Security is breached, alarms go off, and every system in the body becomes a potential target for invaders (antigens). Antigens are substances that invoke an antibody response, but sometimes our antibodies, which are produced to protect us, get confused and target our own tissues (autoimmunity).
Does that sound familiar? Who’s had antibody testing for this or that?
Is this making sense?
Here’s how it all ties together.
See the smoothie ingredients pictured above? They include a mixture of fiber types, along with a rich assortment of nutrients, including vitamins, minerals, antioxidants, and phytochemicals. The American Dietetic Association’s daily recommendation for fiber is 25 grams for women and 38 grams for men. After age 50, the ADA recommendations drop to 21 grams for women and 30 grams for men.
YIKES, in my opinion, that’s way short of what we should be consuming. I’m over 50 and that smoothie of mine alone contains close to 17 grams of fiber. I’m almost at my daily recommendation before 6 AM. Twenty-one grams is not enough to encourage and support a healthy gut microbiome. Not even close.
Recent archeological findings suggest that at least a few of our hunter-forager ancestors consumed up to 135 grams of prebiotic fiber per day. Whoa, I’d call that high-carb, optimal foraging. Not exactly most modern day versions of the Paleo diet. Although 135 grams of fiber per day is a bit much (don’t try that at home, you’ll explode), American’s are definitely short-changing themselves when it comes to fiber — and overall health.
In a nutshell. Eat more plants.
Prebiotic, plant powered smoothie
* Use organic vegetables and fruit, especially if you’re eating the peels. Scrub the peels well before using (see my little veggie scrubber shown above).
2 cups raw greens (add some dandelion greens)
1 medium pear, seeded and chopped
1 medium celery stalk, chopped
1/2 cup chopped cucumber
2 dates, pitted and chopped
1 lemon (with peel), cut into wedges (pick out the obvious seeds) *
2 tablespoons raw oats, finely ground in a coffee grinder *
4 walnut halves, chopped
2 to 4 cups filtered water
Options: I also use raw beets, jicama, burdock root, broccoli stalks, asparagus, bananas, berries, and whatever else I can think of in my smoothies.
Place all ingredients in a high-powered blender (VitaMix, Blendtec, etc.) and blend until smooth.
Nutrition and health bonus
* Retaining the lemon peel doubles the fiber and significantly increases the vitamin C. The peel also contains a phytochemical called d-limonene, a component of the essential oil in citrus. Studies show this substance is chemopreventive and chemotherapeutic, meaning it helps fight against cancer.
* I always add a source of protein to smoothies. Hemp, chia, various nuts and seeds, or raw oats are favorites of mine. Raw oats provide carbohydrate, but the kind I use are also high in protein, iron, and soluble fiber, which in turn provides prebiotic fuel for beneficial microorganisms like bifidobacteria. If you’re worried about phytic acid, some oats have no hull, lessening the content. At least that’s my assumption, although I couldn’t find any research to back this up. My Understanding Normal and Clinical Nutrition book defines phytic acid as: a non-nutrient component of plant seeds; also called phytate. Phytic acid occurs in the husks of grains, legumes, and seeds and is capable of binding minerals such as zinc, iron, calcium, magnesium, and cooper in insoluble complexes in the intestine, which the body excretes. If phytic acid is found in the husk and there is no husk, it makes sense that there’s less (none?) phytic acid in hull-less oats.
Some people with celiac disease don’t do well with oats, even gluten-free oats, so ask your healthcare provider if oats are a good choice for you.
For a little background and a list of what good bacteria do for human health, check out this past post of mine (How much of you is really you?). Check this post for some plant magic, (Talking bacteria and disease-fighting veggies).
I signed up for the American Gut Project to determine my gut microbial makeup. It will be interesting to see how those of us with celiac disease compare to the rest of the participants. I’ll keep you posted. If you want to know what you’re made of, check out the open source, community driven effort to characterize the microbial diversity of the American (and global) gut. Let’s compare bugs!
Peace, love and gut checks!
Chadwich RW, George SE, Claxton ID (1992) “Role of the gastrointestinal mucosa and microflora in the bioactivation of dietary and environmental mutagens or carinogens.” Drug Metabolism Reviews. Vol 24, Issue 4, 425-492.
Crowell P. (1999) “Prevention and Therapy of Cancer by Dietary Monoterpenes.” Journal of Nutrition. Vol 129, No 3, 775-778.
Jenkins et al. (1999) “Nutritional and Health Benefits of Inulin and Oligofructose: Inulin, Oligofructose and Intestinal Function.” Journal of Nutrition. Vol 129, No 7, 1431-1433. http://jn.nutrition.org/content/129/7/1431S.full.pdf+html
Kolida S, Gibson G (2007) “Prebiotic Capacity of Inulin-Type Fructans.” Journal of Nutrition. Vol 137, No 11, 250-256. http://jn.nutrition.org/content/137/11/2503S.full
Leach JD, Sobolik KD. (2010) “High dietary intake of prebiotic-type fructans in the prehistoric Chihuahuan Desert.” British Journal of Nutrition. 103(11):1558-61. http://www.ncbi.nlm.nih.gov/pubmed/20416127
Lopez HW, et al. (1998) “Intestinal Fermentation Lessens the Inhibitory Effects of Phytic Acid on Mineral Absorption in Rats.” Journal of Nutrition. Vol 128, No 7, 1192-1198. http://jn.nutrition.org/content/128/7/1192.full
Meadow JF, et al. (2013) “Significant changes in the skin microbiome mediated by the sport of roller derby.” Peer J 1:e53. http://dx.doi.org/10.7717/peerj.53
Vigsnaes LK, et al. (2011) “In Vitro Fermentation of Sugar Beet Arabinooligosaccharides by Fecal Microbiota Obtained from Patients with Ulcerative Colitis to Selectively Stimulate the Growth of Bifidobacterium spp. and Lactobacillus spp. Applied and Environmental Microbiology. Vol 77, No 23, 8336-8344. http://aem.asm.org/content/77/23/8336.full
Whitney EN, Cataldo CB, Rolfes SR. Understanding Normal and Clinical Nutrition. Wadsworth/Thomson Learning. Belmont, CA. 2002.
Wong et al. (2007) “Carbohydrate digestibility and metabolic effects.” Journal of Nutrition. Vol. 137, no. 11, 2539-2546. http://jn.nutrition.org/content/137/11/2539S.full