Gut bacteria, cholesterol and plaque: A surprising discovery

When cholesterol creeps up, the conversation usually centers on what to cut from your diet—or which medication to add.

But an intriguing discovery raises another question: What should you be feeding the bacteria already living inside you?

Scientists have identified a common gut bacterium that produces a compound capable of interfering with cholesterol production. In mice, that compound reduced artery plaque by around 50%.

That gets my attention. And while researchers explore its treatment potential, there’s a practical part of this story we can put to use: learning which foods help nourish this little-known gut resident.

Quick Answer: Can gut bacteria help lower cholesterol?

A study published in Nature found that Bacteroides uniformis produces pentadecanoic acid, also called C15:0, which inhibits the same cholesterol-making enzyme targeted by statins. Giving the compound to mice reduced artery plaque by around 50%. Researchers haven’t established this treatment’s effectiveness in people, but separate studies suggest certain prebiotic fibers can support the bacterium.

A cholesterol-fighting compound made inside the gut

In the new study published in Nature, researchers found that giving B. uniformis to mice prone to atherosclerosis—the buildup of plaque inside arteries—reduced that buildup.

They then identified a key compound the bacterium makes: pentadecanoic acid.

It acted on an enzyme called HMG-CoA reductase, which helps the liver manufacture cholesterol. Blocking this enzyme suppressed cholesterol production and encouraged the liver to remove more LDL cholesterol from the bloodstream.

That’s the same enzyme statin drugs target, although this discovery doesn’t establish the bacterial compound as equivalent to a statin.

When researchers administered the compound, plaque burden fell by about 50%. They also found lower levels of the compound in people with abnormal blood fats. That human finding was an association, rather than proof of a treatment benefit.

The finding opens a fascinating possibility: Some of our cardiovascular defenses may depend partly on what our gut microbes manufacture.

Feed the bacteria you want to support

You can’t currently pick up B. uniformis as an over-the-counter probiotic supplement. But these bacteria are fairly common and likely already in your microbiome. That makes it especially important to feed the ones already living in your gut.

This is where prebiotics come in. A probiotic supplies microorganisms; a prebiotic provides food that helps support them.

But “eat more fiber” leaves out something useful: Different microbes respond to different fibers.

Research on B. uniformis gives us several specific places to start.

1. Give inulin-rich foods a regular place on your plate

Inulin is a fermentable fiber found in chicory root, Jerusalem artichokes, garlic, onions and leeks.

Direct human evidence supports this connection. In a controlled dietary study published in Scientific Reports, researchers observed an increase in B. uniformis in response to inulin supplementation. That doesn’t mean every serving of onions produces the same response, but it provides a reason to pay attention to this particular fiber.

You can work these foods into meals you already enjoy:

• Add onions and garlic to soups, eggs or roasted vegetables.
• Use leeks in a vegetable soup.
• Try a small serving of roasted Jerusalem artichokes.

These are familiar ingredients with a potentially useful second job: supplying food for your gut microbes.

2. Include pectin from apples and citrus

Pectin is another fermentable fiber, found in foods such as apples and citrus fruit.

Laboratory research shows that B. uniformis can use pectin, along with inulin and other complex carbohydrates. The researchers also found that the fiber available to the bacterium changed its activity and the compounds it produced.

That makes an apple or an orange more than a convenient snack. It supplies material microbes can use

Choose whole fruit regularly. You don’t need to start eating citrus peels to include pectin in your diet.

3. Make room for resistant starch

Resistant starch gets its name because it resists digestion in the small intestine, reaching the colon where gut bacteria can feed on it.

Sources include green bananas and potatoes or rice that have been cooked and cooled. Laboratory research shows that B. uniformis can efficiently break down resistant starch, giving us another way to help nourish this gut resident.

Try a chilled potato salad, add cooked-and-cooled rice to a lunch bowl, or blend some green banana into a smoothie. Cool cooked potatoes and rice promptly and keep them refrigerated.

4. Feed your gut with polyphenol-rich foods

Polyphenols—the plant compounds abundant in berries, green tea and red wine—also deserve a place in this picture.

In a small human study, drinking red wine significantly increased B. uniformis. Researchers compared regular wine, dealcoholized wine and gin to explore the contributions of polyphenols and alcohol. Both wines increased several bacterial groups, supporting the ability of polyphenols to influence gut bacteria without alcohol.

For everyday meals, berries and green tea offer practical, nonalcoholic ways to get more polyphenols. Although the wine study didn’t test these foods, they’re sensible choices for a diet aimed at nourishing your gut.

Add blueberries or blackberries to breakfast, enjoy berries as a snack, or make unsweetened green tea part of your afternoon routine.

Start with one meal

No established food regimen has been studied to reproduce the plaque reduction seen in these mice.

But it gives the advice to nourish your gut a more concrete purpose.

Start with onions or leeks with dinner, an apple for a snack, or a refrigerated potato salad alongside lunch. Increase fermentable fiber gradually if you’re prone to gas or bloating.

The compelling possibility is that food helps determine which useful compounds our resident microbes can make. Supporting those microbes may become an increasingly important part of understanding heart health.

Sources:

• A gut microbial odd-chain fatty acid alleviates atherosclerosis in mice — Nature.
• Predictability and persistence of prebiotic dietary supplementation in a healthy human cohort — Scientific Reports.
• The Glycolytic Versatility of Bacteroides uniformis CECT 7771 and Its Genome Response to Oligo and Polysaccharides — Frontiers in Cellular and Infection Microbiology.
• Bacteroides uniformis ATCC 8492 Utilizes Lotus Seed Resistant Starch via a PUL18-Driven Exterior-to-Interior Degradation Strategy — Journal of Agricultural and Food Chemistry.
• Influence of red wine polyphenols and ethanol on the gut microbiota ecology and biochemical biomarkers — The American Journal of Clinical Nutrition.

FAQ: About B. uniformis, cholesterol and artery plaque in mice

What is Bacteroides uniformis?

Bacteroides uniformis is a bacterium commonly found in the human gut. It can break down certain dietary fibers and produce compounds that influence the body, including pentadecanoic acid, also called C15:0.

How could Bacteroides uniformis affect cholesterol?

Researchers found that a compound it produces inhibits HMG-CoA reductase, an enzyme the liver uses to make cholesterol. In mice, the compound improved blood lipid levels and reduced artery plaque by around 50%. Its effectiveness as a treatment in people has not been established.

How can you support Bacteroides uniformis naturally?

Research supports feeding it certain fermentable fibers. Inulin supplementation has increased B. uniformis in a human study, while laboratory research shows it can use pectin and resistant starch. Food sources include onions, garlic, leeks, apples, citrus fruit, green bananas and cooked-and-cooled potatoes or rice.

What is the difference between probiotics and prebiotics?

Probiotics supply live microorganisms. Prebiotics provide substances that microorganisms use as food. Supporting bacteria already living in your gut involves supplying the fibers and other compounds they can use.

Do you need to drink red wine to get polyphenols?

No. Berries and green tea provide polyphenols without alcohol. A small study found that red wine significantly increased B. uniformis, while both regular and dealcoholized wine increased several bacterial groups. The study did not test berries or green tea.