Whole Grains, Oats, and Gut Microbiota
First off, I have to point out that this paper was made possible with a grant from Quaker Oats. I always hate seeing things like that because I am always telling people to 'follow the money,' and in this case it leads back to this guy:
Looking over the paper, it seems to agree with things I have read about gut health and it makes me feel a bit more confident to recommend oats as part of a gut-friendly diet.
Maybe watch this first, to get you in the mood (Thanks, Newbie!).
The abstract we saw last week:
The gut microbiota plays important roles in proper gut function and can contribute to or help prevent disease. Whole grains, including oats, constitute important sources of nutrients for the gut microbiota and contribute to a healthy gut microbiome. In particular, whole grains provide NSP and resistant starch, unsaturated TAG and complex lipids, and phenolics. The composition of these constituents is unique in oats compared with other whole grains. Therefore, oats may contribute distinctive effects on gut health relative to other grains. Studies designed to determine these effects may uncover new human-health benefits of oat consumption.
First, the paper discussed whole grains. Whole grains I can deal with. Weston A. Price loved whole grains and the WAPF recommends them as well. The problem with whole grains has been a mental one for me, coming from a Paleo background...how many times have we heard that grain is not human food, only animal food, and that grains "don't want to be eaten" so they have devised strategies to prevent animals from eating them?
I have however loosened my stance on grains and have been eating oats, buckwheat, and some others the last couple of years.
On whole grains:
Although the principal non-digestible components in whole grains are cross-linked arabinoxylan and cellulose (see online supplementary Table S1) – substrates that are generally considered poor for gut microbial fermentation – whole grains have the potential to play an important role in maintaining a healthy gut microbiota. Two human trials have suggested a bifidogenic effect from the consumption of whole-grain cereals(6,7). Some strains of Bifidobacterium have been reported in the literature as markers of a healthy gut microbiota(3). Other studies have shown increases in butyrate-producing bacteria, including Roseburia, Eubacterium rectale and the Clostridium leptum group (which includes Faecalibacterium prausnitzii)(11,12).
They don't really define "whole grains" in the paper, they mention "cereal" grains which are grains like wheat, barley, corn, and oats. I don't care what it says in this paper, though, I won't be rushing out to buy any wheat soon! The paper mentions the three big health benefits of whole grains being fiber, lipids, and phenolics (antioxidants).
Then the paper goes on to discuss oats in great detail. Some of this I knew and some was quite new.
One of the most beneficial aspects of oats may be their Beta-Glucan content, but also a whopping 15% RS in thick-cut oats. If you remember from lots of the earlier talk on RS, it's made more effective when eating it alongside other fiber types, so in this respect, oatmeal should be a fantastic food for healthy guts.
I won't bore you with a lengthy discussion on the fiber found in oats, please have a read if you are curious...but I would like to bore you with this paragraph on the phenolics found in oats. Phenolics are antioxidants:
While the majority of phenolics in oats are bound ferulic acid, which is similar to other whole grains, oats also contain some unique phenolics including avenacosylates, avenacins and avenanthramides. Avenacosylates are esters of ferulic or caffeic acid with a long-chain wax alcohol (policosanol) and are present in oats at about 50–200mg ferulic acid equivalents/kg(9). The avenacins are pentacyclic triterpene alcohol glycosides containing esters of aminophenolic or benzoic acid(9). Avenanthramides are conjugates of a phenylpropanoid with anthranilic acid or 5-hydroxy anthranilic acid and are present in oats in widely varying concentrations similar to the avenocosylates(9). It is likely that these compounds are metabolised by the gut microbiota, but this has not been reported in detail(71). Some data suggest that they may function as anti-inflammatory molecules and protect the gut mucosa by modulating NF-kB activation(72).
I did a little digging into the avenacins found these plant chemicals are used to repel microbial pests from the growing oats and have an anti-fungal effect. It is very likely that avenacins result in a healthier gut. The avenanthramides are even more interesting! One study says:
Oats are known to be a healthy food for the heart due mainly to their high beta-glucan content. In addition, they contain more than 20 unique polyphenols, avenanthramides, which have shown strong antioxidant activity in vitro and in vivo. The polyphenols of oats have also recently been shown to exhibit anti-inflammatory, antiproliferative, and anti-itching activity, which may provide additional protection against coronary heart disease, colon cancer, and skin irritation
But caution needs to be taken as some people may be sensitive to these compounds:
Coeliac disease (celiac disease) is often associated with the ingestion of wheat, or more specifically, a group of proteins called prolamins, including gluten. Oats lack many of the prolamins found in wheat, but do contain avenin. Avenin is toxic to the intestinal mucosa of avenin-sensitive individuals, and can trigger a reaction in these coeliacs. (Wikipedia)
Some more on Avenacins (hattip, Gemma):
Glycosyltransferases from Oat (Avena) Implicated in the Acylation of Avenacins
Plants produce a huge array of specialized metabolites that have important functions in defense against biotic and abiotic stresses. Many of these compounds are glycosylated by family 1 glycosyltransferases (GTs). Oats (Avena spp.) make root-derived antimicrobial triterpenes (avenacins) that provide protection against soil-borne diseases. The ability to synthesize avenacins has evolved since the divergence of oats from other cereals and grasses.and
Compromised disease resistance in saponin-deficient plants
This study investigates the role of saponins, an important group of preformed plant secondary metabolites, in protecting plants against fungal attack. Saponins are glycosylated triterpenoid, steroid, or steroidal alkaloid molecules that occur constitutively in many plant species (1, 15–17). Because many saponins have potent antifungal activity and are often present at high levels in healthy plants, these molecules have been implicated as antimicrobial phytoprotectants (1, 3, 15–17). Direct genetic evidence for this is, however, lacking. This work involves a family of four structurally related triterpenoid saponins, avenacins A-1, B-1, A-2, and B-2, found in the roots of oat (Avena spp.) (18, 19) (Fig. (Fig.1).1). These saponins have been implicated as determinants of the resistance of oats to the root-infecting fungus Gaeumannomyces graminis var. tritici (20), which causes “take-all” disease of wheat and barley but is unable to infect oats.
The conclusion from this Quaker Oat funded paper does give good reasons to include oats in a healthy diet:
Oats are a unique whole grain that may contribute distinctive effects on the gut microbiota. These effects could be due to the high b-glucan content, the high lipid content or the unique antioxidant profile. b-Glucan fermentation could contribute to the hypocholesterolaemic properties of oats(25). Furthermore, b-glucan may slow the rate of starch digestion and help increase the RS content of oats relative to other grains that are low in b-glucan(65,66). Oat lipids and antioxidants have not been studied in relation to gut health, but research in other whole grains suggests that they influence the types of bacteria that make up the microbiota and impact on host health(47,55,72). The microbiota and gut health are at the intersection of emerging research, particularly when considering the demonstrated and possible health implications of whole grains and dietary fibre that are identified in oats.
The Downside of OatsAs I write this, I keep thinking there are some good reasons that the paleo community shunned the oat. I took a look at Mark's Daily Apple Oat Blog, and saw that the only reason they could come up with was phytic acid. Phytic acid has been implicated in binding with minerals like zinc, iron, calcium, and magnesuim causing deficiencies in lab studies. Phytic acid is one of the paleo/Perfect Health Diet 'antinutrients' you hear about frequently. About the only I could find that Paul Jaminet said about phytic acid is:
Phytic acid is also not all that dangerous. It is a mineral chelator, which leads to minerals being excreted rather than absorbed. The primary risk is that it will induce a mineral deficiency. Because phytic acid preferentially binds iron, which can be dangerous, some advocate its supplementation.We don’t agree with that, but we don’t consider the small amount of phytic acid in rice to be dangerous, especially given that we recommend a mineral-rich diet and supplementation with both a multivitamin and specific key minerals.
The Weston A. Price Foundation had a lengthy discussion on phytic acid, saying about oats:
.Oats contain very little phytase, especially after commercial heat treatment, and require a very long preparation period to completely reduce phytic acid levels. Soaking oats at 77 degrees F for 16 hours resulted in no reduction of phytic acid, nor did germination for up to three days at this temperature.63 However, malting (sprouting) oats for five days at 52 degrees F and then soaking for 17 hours at 120 degrees F removes 98 percent of phytates. Adding malted rye further enhances oat phytate reduction.64 Without initial germination, even a five-day soaking at a warm temperature in acidic liquid may result in an insignificant reduction in phytate due to the low phytase content of oats. On the plus side, the process of rolling oats removes a at least part of the bran, where a large portion of the phytic acid resides.How do we square what we know about oats with the fact that oats were a staple in the diet of the Scots and Gaelic islanders, a people known for their robust good health and freedom from tooth decay? For one thing, high amounts of vitamin D from cod’s liver and other sources, helps prevent calcium losses from the high oat diet. Absorbable calcium from raw dairy products, consumed in abundance on mainland Scotland, provides additional protection.In addition, it is likely that a good part of the phytase remained in the oats of yore, which partially germinated in stacks left for a period in the field, were not heat treated and were hand rolled immediately prior to preparation. And some Scottish and Gaelic recipes do call for a long fermentation of oats before and even after they are cooked.Unprocessed Irish or Scottish oats, which have not been heated to high temperatures, are availabile in some health food stores and on the internet. One study found that unheated oats had the same phytase activity as wheat.65 They should be soaked in acidulated water for as long as twenty-four hours on top of a hot plate to keep them at about 100 degrees F. This will reduce a part of the phytic acid as well as the levels of other anti-nutrients, and result in a more digestible product. Overnight fermenting of rolled oats using a rye starter—or even with the addition of a small amount of fresh rye flour—may result in a fairly decent reduction of phytate levels. It is unclear whether heat-treated oats are healthy to eat regularly
From the same WAPF link as above, here is a table showing relative amounts of phytic acid in some common foods:
FIGURE 1: FOOD SOURCES OF PHYTIC ACID7
As a percentage of dry weight
|Sesame seed flour||5.36||5.36|
|Soy protein concentrate||1.24||2.17|
|Whole wheat bread||0.43||1.05|
I'm not sure why the disparity between "oats" and "oatmeal," though.
So, in making up your mind about oats, I'll throw another wrench in the works...some say that phytic acid actually may be beneficial! Looking at Figure 1, I see lots of foods that have been consumed by many cultures known for their great health. And when I Googled, "Phytic Acid Beneficial" I came up with many papers saying that phytic acid is nothing to worry about, and in fact is beneficial!
From: The role of phytic acid in legumes: antinutrient or beneficial function?
This review describes the present state of knowledge about phytic acid (phytate), which is often present in legume seeds. The antinutritional effects of phytic acid primarily relate to the strong chelating associated with its six reactive phosphate groups. Its ability to complex with proteins and particularly with minerals has been a subject of investigation from chemical and nutritional viewpoints. The hydrolysis of phytate into inositol and phosphates or phosphoric acid occurs as a result of phytase or nonenzymatic cleavage. Enzymes capable of hydrolysing phytates are widely distributed in micro-organisms, plants and animals. Phytases act in a stepwise manner to catalyse the hydrolysis of phytic acid. To reduce or eliminate the chelating ability of phytate, dephosphorylation of hexa- and penta-phosphate forms is essential since a high degree of phosphorylation is necessary to bind minerals. There are several methods of decreasing the inhibitory effect of phytic acid on mineral absorption (cooking, germination, fermentation, soaking, autolysis). Nevertheless, inositol hexaphosphate is receiving increased attention owing to its role in cancer prevention and/or therapy and its hypocholesterolaemic effect.
Iinositol hexaphosphate is the "official" name for phytic acid. And from Cancer.org we learn:
Inositol HexaphosphateOther common name(s): IP6, IP-6, InsP-6, inositol, phytic acid, phytate, myo-inositol hexaphosphateScientific/medical name(s): inositol-1,2,3,4,5,6-hexakisphosphate
Inositol hexaphosphate (IP6) is a chemical found in beans, brown rice, corn, sesame seeds, wheat bran, and other high-fiber foods. It is converted into compounds in the body that are used by cells to relay outside messages to the cell nucleus. IP6 also aids the body in its use, or metabolism, of calcium and other minerals.
All of the evidence regarding the anti-cancer effects of IP6 has come from laboratory cell cultures and animal studies. Laboratory studies of cell cultures have shown that IP6 may help put cancer cells on a path toward normal cell death and may help keep them from spreading to other parts of the body. It may also affect the growth of blood vessels that supply the tumor and the immune system in general. These studies have shown IP6 may have activity against cancer of the pancreas, breast, prostate, colon, and other types of cancer. Results of some studies in cells have also suggested that IP6 may help certain chemotherapy or hormone therapy drugs work better.Studies in animals have found that supplementing the animals’ diets with IP6 may help prevent tumors from forming in the prostate, lung, colon, skin, and other areas. While animal and laboratory studies may show a certain compound holds promise as a helpful treatment, further studies are needed to find out if the results apply to humans. One preliminary human study suggested that IP6 may cause regression of precancerous lung changes in smokers. IP6 has not yet been studied in humans as a treatment for cancer.One small study done in Croatia found that IP6 helped ease treatment side effects for women getting chemotherapy for breast cancer. The women getting IP6 also scored higher on quality-of-life assessments than women not getting IP6. But only 14 women were included in this study (7 of whom got IP6), so more studies of this possible role for IP6 are needed.Inositol hexaphosphate and similar chemicals have also been studied for treating polycystic ovary syndrome, panic disorders, autism, obsessive-compulsive disorders, Alzheimer disease, post-traumatic stress disorders, and depression. Researchers have reached no firm conclusions about its impact on these conditions.
So, really, what's not to like about oats? Resistant Starch, Beta-Glucans, insoluble fiber, healthy fats, and phytic acid in smaller amounts than many other foods considered 'paleo' and healthy. And they look pretty good nutrition-wise, too. From Wikipedia:
|Nutritional value per 100 g (3.5 oz)|
|Energy||1,628 kJ (389 kcal)|
|Dietary fibre||10.6 g|
|β-glucan (soluble fibre)||4 g|
|Percentages are roughly approximated using US recommendations for adults.|
Source: USDA Nutrient Database
Let's look at the different types of oats available and see what there is to choose from:It appears there are two main ways that oats are processed: Flaking and Milling.
- Oat bran milling
Bob's Red Mill sells 23 different kinds of oats from 'Quick Rolled' to 'Thick cut.' I personally think that just about any kind are fine with a personal preference towards the thick cut types, just because the paper that started this blog said the thicker the oat flakes, the more RS.
Soaking your oats:I've also seen much talk about people soaking their oats. Maybe this is needed, maybe not. But if you enjoy it that way, it does seem to be a traditional way of preparing oats:
As a whole grain, oats contain a hearty dose of fiber, as well as multiple health-enhancing nutrients, including phosphorous, potassium, manganese and selenium. Whether you eat oat groat, steel-cut oats or rolled oats, soaking them ahead of time softens the oat kernels, which makes them more digestible and produces a rich, creamy blend of tender, moist oats. Mix the soaked oats with a handful of fruit and nuts and eat them cold as muesli. Or warm them on the stove over a medium-low heat for five minutes before serving them as a nutritious, filling breakfast or snack.
The article goes on to describe the soaking process which is simply to measure out the amount of oats you want to eat, mix them with water, milk, yogurt, or fruit juice, and refrigerate for 12-24 hours. This is the traditional way of preparing muesli as well.
Fermenting Oats:If you are into fermented foods, oats can be fermented, too! Lots of studies show that fermentation reduces phytates and gives us a good dose of probiotics: Here, here, and here. (hattip, Gemma)
A good description of how to prepare fermented oats can be found here and here. Basically, just soaking your oats overnight at room temperature should induce some fermentation as it does with beans. Others recommend mixing the oats with yogurt and soaking overnight at room temperature. The second link shows how to do a more long-term fermentation, a "perpetual soured porridge" as they call it:
- Crack whole oat groats into something like a steel-cut oat. It will look like a combination of flour and pieces of whole oats. You can grind it as fine as you’d like, just make sure the oat groats have been broken up and the starchy insides exposed.
- Combine a few cups of these (I just use two scoops from our grain bucket, the equivalent of about 2-3 cups) with enough water so that you can stir it easily but it is not too soupy. I use a half gallon jar for this.
- You can, optionally, add some whey at this point to kick-start the fermenting process. I did just a couple of tablespoons off of our kefir and it seems to have worked well.
- Cover with a cloth or a coffee filter and a rubber band or canning ring. Let sit in a warm place for a few days or until it starts to smell sour and have little bubbles.
2 Cup(s) granulated sugar
8 Tablespoon(s) (1 stick) margarine
1/2 Cup(s) Low-Fat Milk
1/3 Cup(s) baking cocoa
3 Cup(s) Quaker® Oats (quick or old fashioned, uncooked)
In large saucepan, combine sugar, margarine, milk and cocoa. Bring to boil over medium heat, stirring frequently. Continue boiling 3 minutes, stirring frequently. Remove from heat. Stir in oats.* Drop by tablespoonfuls onto waxed paper. Let stand until firm. Store tightly covered.
Serving Tips: *If using old fashioned oats, cool mixture in saucepan 5 minutes.
This recipe was right from the Quaker Oat website...here's how to "RS-ify" and "Paleo-ize" this recipe!
VEGETABLE PHARM RECOMMENDED INGREDIENTS:
1 cup coconut sugar, honey, maple syrup or 1/2 cup stevia, etc...
8 Tablespoons of real butter or coconut oil
1/2 cup of Full-Fat Milk
1/2 cup of baking cocoa
1 cup of potato starch
3 cups of thick cut oats
Optional: coconut flakes, peanut butter, vanilla, nuts
Make this version just like above, but let the hot mixture cool a bit before adding the oats and ensure it is very cool before adding the potato starch. Spoon onto a no-stick pan or waxed paper and put in the fridge overnight.
Bottom-line: I see no reason to exclude oats from a healthy diet. Eat them raw or cooked, soaked, feremented, or straight out of the bag. But as with everything...in moderation!
OK, any of you oat-lovers want to come out of the closet now and tell us in the comments how to eat oats?