Tag Archive for: SCFA

SFCA, Sodium Intake, and High Blood Pressure

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Researchers in the United Kingdom recruited people with elevated systolic and diastolic blood pressure for a randomized, placebo-controlled, crossover study on diet and blood pressure. The scientists put all 145 subjects on a low-sodium diet for six weeks. Half the subjects was given a placebo while the other half was given a slow-release sodium supplement. After six weeks, the subjects were crossed over to the other group for another six weeks. The objective was to see if sodium intake impacted the microbiome and short-chain fatty acids (SCFA) production to reduce blood pressure.

In a perfect world, researchers would take stool samples under all conditions to test for changes in microbe content, but that approach is expensive and time-consuming. Instead they chose to monitor changes in SCFA because they’ve been associated with blood pressure.

Researchers found that while taking the placebo, subjects on the low-sodium diet saw all SCFA increase; 2-methylbutyrate, butyrate, hexanoate, isobutyrate, and valerate were significantly increased. The increases in SCFA were associated with reductions in blood pressure and arterial-wall stretchability.

What does it mean? We’ve known for decades that sodium plays a role in blood pressure. This study demonstrated that sodium reduction directly increased the production of SCFA, which then lowered blood pressure. What we don’t know is the specific beneficial microbes affected or exactly how sodium negatively impacts them. Research continues and I’m sure we’ll find that out eventually.

The Bottom Line

On the other hand, it may not be necessary to find out. Scientists like me always want to know the specific bacteria and the mechanism by how it works. We know that fluid retention is involved somewhere. But we already know that if we reduce sodium, we’ll positively impact our blood pressure. We also know that fiber is the essential food for these SCFA-producing bacteria in our microbiome. If we focus on a more fiber-rich diet as well as take a fiber supplement, we may be able to increase our odds of reducing blood pressure without medication. If we need the meds, we take them, but if we can do it by feeding our microbiome, that’s even better.

What are you prepared to do today?

        Dr. Chet

References:
1. Hypertension. 2020;76:73–79.
2. Benoit Chassaing, Andrew T. Gewirtz, in Physiology of the Gastrointestinal Tract (Sixth Edition), 2018.

Health Benefits of SCFA

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Let’s continue our look at short-chain fatty acids (SCFA) and what they do besides produce energy. Most of these are observational in nature; by that I mean when SCFA go up or down, effects are observed. What we don’t know at this point is why.

For example, when diabetic animals are given the SCFAs acetate and propionate, they maintain better glucose control. That means that adding SCFA to their diet can improve their ability to maintain blood sugar levels. Wait a second; is this the same acetate that’s found in vinegar? Yes. The problem is that the studies don’t provide consistent results.

The same is true for fat storage. When SCFA levels go up, fat storage appears to go down, but drinking vinegar doesn’t necessarily provide that benefit. Observational studies show that as SCFA levels made by the body go up, fat storage goes down. That can prevent weight gain, but we don’t know whether it causes weight loss. The same is true for cholesterol levels; SCFA are associated with lower cholesterol levels.

The problem is that we don’t know the precise mechanisms yet. In other words, what does making SCFA do to the metabolic systems in the body? To the genes? Or receptors for various functions? That’s what scientists are working on. Further, exactly what type of bacteria produce the right SCFA? There’s general agreement that Bifidobacteria produce acetate and propionate when fermenting fiber, but which Bifidobacterium? There are over 50 varieties. Maybe more than one—they may interact in sequence. We don’t know at this point.

What role do SCFA have in controlling blood pressure? Does sodium also have an impact on SCFA production? We’ll take a look at a recent study on Saturday.

What are you prepared to do today?

        Dr. Chet

References:
1. Benoit Chassaing, Andrew T. Gewirtz, in Physiology of the Gastrointestinal Tract (Sixth Edition), 2018.
2. Front Microbiol. 2016; 7: 925. doi: 10.3389/fmicb.2016.00925

Short-Chain Fatty Acids: DIY Nutrition

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Short-chain fatty acids (SCFA) are critical to your health and well-being, yet you may not really know where they come from or what they do. In my opinion, the most interesting thing about SCFA is that they’re not generally found in our diet; we make them ourselves! We do that when bacteria in the microbiome work to ferment digestible fiber.

By definition, SCFA contain less than six carbon molecules. The three you may have heard about are acetate, propionate, and butyrate. SCFA can provide us with up to 10% of our energy needs. They’re especially important to colonocytes, a type of endothelial cells of the large intestine that need energy to digest and absorb food that we use to produce the rest of the energy we need.

I’ll cover what else SCFA do on Thursday. In the meantime, one way to increase the production of SCFA is to get more fiber, whether from foods or supplements. It’s especially important after a course of antibiotics; research has shown that after the microbiome is upset by antibiotics, the production of SCFA can be impaired, which impacts many biological processes.

The monthly Insider Conference Call is tomorrow night at 9 p.m. Eastern Time. You can still participate by becoming an Insider by 8 p.m. tomorrow night. If you have questions about COVID-19 or any other health topic, this is your chance to get answers. I hope to talk with you then.

What are you prepared to do today?

        Dr. Chet

Reference: Benoit Chassaing, Andrew T. Gewirtz, in Physiology of the Gastrointestinal Tract (Sixth Edition), 2018.

Will the Diet of Your Culture Improve Your Microbiome?

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Does the diet of your ancestors impact your microbiome? A review examined whether the common foods found in specific cultures can benefit people of that culture who are following a diet high in refined carbohydrate and low in fiber, as is common in the U.S. Let’s take a look.

The Gold Standard: the Mediterranean Diet

The Mediterranean diet has been studied more than any other; it emphasizes vegetables, whole grains, fish and seafood, nuts and seeds, olive oil, fruit, and limited sweets. The benefits for reducing heart disease, hypertension, and T2D are well documented, and we’ve always assumed that the Mediterranean diet is appropriate for everyone. But is it? The point to this review is that while there are similarities, there are cultural differences that may be important.

For example, there are more tubers (root vegetables) in African diets and virtually none in most Asian cultures. The Latin diet has more dairy products while some Asian diets contain almost none. If you want to become more familiar with cultural diets, check out www.oldwayspt.org. It’s a non-profit organization that has developed cultural appropriate diets and teaches people to prepare foods using traditional cultural spices.

It makes sense; one size does not fit all. One interview in the paper was with an Eastern Indian physician who had always recommended the Mediterranean diet to her clients of Indian descent, but the whole grains of the Mediterranean diet were not the same as traditional Indian grains. Once she changed the types of grains and other high-fiber foods to more culturally appropriate choices, her patients did better in following a higher fiber diet.

The Benefits of a Culturally Appropriate Diet

Simply stated, people are more inclined to follow a healthier, high-fiber diet if it’s based on their own culture. The differences in grains and vegetables may be subtle but seem to be important. The tastes and flavors may be more familiar to first or second generation immigrants.

There is also speculation that the microbiomes of people from varying cultures may have an evolutionary aspect. In other words, whether you’re a recent immigrant or a fourth generation of immigrants as I am, your microbiomes may respond better to foods that your ancestors have eaten for generations. Remember the short-chain fatty acids (SCFA) in the Thursday Memo this week? They may be dependent, not just on fiber, but fiber from the foods of your ancestors.

The Bottom Line

This paper gives us something to think about. What if we ate a more plant-based diet that’s more culturally based? I think it’s worth a try. It doesn’t mean that you won’t benefit from eating a high-fiber food that’s not culturally based; there’s no question that you will. But if you ate culturally based foods and they were prepared based on cultural tastes, you might decide to eat more of them and you might get more benefit.

The first thing I did was to look at traditional foods from my ancestors in Poland and other eastern European cultures. I’m not done yet, but it seems cabbages and root vegetables are definitely part of my future diet; I’ll keep you posted as I research my diet further. In the meantime, check out Oldways to get some perspective on what culturally appropriate foods may benefit your diet. If you’re an African-American man married to a Chinese-Canadian woman, you’re going to have some very interesting meals.

What are you prepared to do today?

        Dr. Chet

References:
1. JAMA. 2019; doi: 10.1001/jama.2019.18431.
2. www.oldwayspt.org.

Does Fiber Improve Your Microbiome?

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Now let’s look at the results of increasing dietary fiber for people with diabetes. Researchers recruited over 50 type 2 diabetics (T2D) for a 12-week study. The control group was given standard recommendations for a healthy diabetic diet. All current medications were maintained and both groups received acarbose, a starch blocker. The experimental group was put on a diet of prepared high-fiber foods and a diet higher in vegetables and fruits. Stool samples were collected periodically to assess the impact of the diet on the microbiome.

While the variables were straightforward, the analytic techniques were extraordinarily complex. It’s easy to say you want to examine the microbiome, but that’s not simple to do with thousands of types of microbes to analyze. Several types of bacteria from different species responded to the increase in fiber: bacteria that produced short-chain fatty acids (SCFA). The SCFAs are important because they feed the cells in the gut that do all the work during digestion and absorption.

HbA1c levels decreased faster and in a higher percentage of subjects in the experimental group than the control group. The fiber group also lost more weight and their blood lipids improved more than controls.

This was a small study, limited by the complexity of analyzing the microbiome, but the improvement in T2D simply due to an increase in fiber from foods is important. One more thing: this was a Chinese study, so typical high fiber foods from China were used. Is that important? We’ll find out Saturday.

What are you prepared to do today?

        Dr. Chet

Reference: Science. 2018. 359:1151–1156.