Researchers studied over 21,000 American adults to understand how diet affects cholesterol levels and gut health. They created a scoring system to measure how “gut-friendly” people’s diets were based on 14 different food components. People who ate more gut-friendly foods had significantly lower chances of developing high cholesterol. The study suggests that eating foods that support healthy gut bacteria may help prevent high cholesterol by reducing inflammation in the body. This research opens new ways to think about managing cholesterol through diet rather than just medication.

The Quick Take

  • What they studied: Whether eating foods that are good for your gut bacteria helps prevent high cholesterol, and how inflammation might explain this connection
  • Who participated: 21,352 adults living in the United States who participated in national health surveys between 2010 and 2020, representing a diverse cross-section of the American population
  • Key finding: People with the highest gut-friendly diet scores were about 19% less likely to have high cholesterol compared to those with the lowest scores. The relationship was consistent—the better the diet, the lower the cholesterol risk
  • What it means for you: Eating more foods that support healthy gut bacteria (like fiber-rich foods, whole grains, and certain vegetables) may help keep your cholesterol levels normal. However, this study shows association, not proof of cause-and-effect, so talk to your doctor before making major diet changes

The Research Details

This was a large observational study using data from the National Health and Nutrition Examination Survey (NHANES), a program that tracks the health of Americans over many years. Researchers looked at what people ate using 24-hour food recall interviews, where participants describe everything they consumed in one day. They then scored each person’s diet based on 14 components known to support healthy gut bacteria, such as whole grains, vegetables, fruits, legumes, and other fiber-rich foods.

The researchers compared these diet scores to whether people had high cholesterol (either diagnosed by a doctor or managed with medication). They used statistical methods to account for other factors that might affect cholesterol, like age, exercise, smoking, and overall health status. They also performed special analyses to see if inflammation in the body might explain why better diets lead to better cholesterol levels.

This type of study is valuable because it includes a large, representative sample of real Americans and their actual eating patterns, making the findings more applicable to everyday life than laboratory studies.

Understanding how diet affects cholesterol through gut health is important because high cholesterol is a major risk factor for heart disease, which is the leading cause of death in the United States. Most current cholesterol management focuses on medication, but this research suggests that dietary changes supporting gut health might offer a natural, preventive approach. The study also identifies inflammation as a potential mechanism, which could lead to new treatment strategies.

This study has several strengths: it included a very large, nationally representative sample of Americans, used standardized methods to assess diet and health, and accounted for many confounding factors. However, because it’s observational rather than experimental, we can’t prove that the diet caused the lower cholesterol—only that they’re associated. The study relied on people’s memory of what they ate, which can be imperfect. Additionally, the cross-sectional design means we’re looking at a snapshot in time rather than following people over years to see if diet changes actually prevent high cholesterol.

What the Results Show

The main finding was that people with the highest scores on the gut-friendly diet index had significantly lower odds of having high cholesterol. Specifically, those in the top category had about 19% lower odds compared to those in the bottom category. This relationship held true even after accounting for age, sex, race, education, physical activity, smoking, and other health factors.

The researchers also found a dose-response relationship, meaning that as diet scores improved incrementally, cholesterol risk decreased in a predictable pattern. This suggests the benefit isn’t just from reaching a certain threshold but increases with each improvement in diet quality.

When the researchers looked at inflammation levels in the blood (measured by a marker called the systemic immune-inflammation index), they found that inflammation accounted for about 18% of the protective effect of the gut-friendly diet. This suggests that one way these diets help is by reducing body-wide inflammation, which is linked to high cholesterol.

The study confirmed that the relationship between diet quality and cholesterol was consistent across different statistical models and analytical approaches. The findings were robust, meaning they held up even when researchers adjusted for various other factors and used different analytical methods. This consistency strengthens confidence in the results.

This research builds on growing evidence that gut bacteria play an important role in cholesterol metabolism. Previous studies have shown that the composition of gut bacteria affects how the body processes dietary fats and cholesterol. This study is novel because it uses a comprehensive scoring system (the DI-GM) specifically designed to capture the microbiota-supporting aspects of diet, rather than just looking at individual nutrients. The findings align with other research showing that fiber-rich, plant-based dietary patterns support healthy cholesterol levels.

The study cannot prove cause-and-effect because it’s observational—we can only say that better diets are associated with better cholesterol levels. People’s diets were assessed based on a single 24-hour recall, which may not represent their typical eating patterns. The study included mostly U.S. adults, so results may not apply to other populations with different genetic backgrounds or food availability. Additionally, people with high cholesterol might have already changed their diets, making it unclear whether the diet caused the lower cholesterol or vice versa. The study also couldn’t account for all possible factors affecting cholesterol, such as genetic predisposition or unmeasured lifestyle factors.

The Bottom Line

Consider increasing your intake of foods known to support healthy gut bacteria, including whole grains, vegetables, fruits, legumes (beans and lentils), nuts, and seeds. These foods are high in fiber and contain compounds that feed beneficial bacteria. This dietary approach may help maintain healthy cholesterol levels as part of a comprehensive heart-health strategy. However, if you have high cholesterol or are taking cholesterol medication, continue following your doctor’s advice and don’t stop medications without medical guidance. This research suggests diet is one tool among many for cholesterol management.

This research is relevant to anyone concerned about heart health or cholesterol levels, particularly those with family histories of high cholesterol or heart disease. It’s especially valuable for people interested in preventing high cholesterol through dietary means before medication becomes necessary. However, people with existing high cholesterol should work with their healthcare provider rather than relying solely on diet changes. The findings apply most directly to U.S. adults but may have relevance to other populations.

Changes in cholesterol levels from dietary modifications typically take 4-12 weeks to become apparent, though improvements in gut bacteria composition may occur within 2-4 weeks. Sustained benefits require maintaining the dietary changes long-term. Don’t expect immediate results, but consistent adherence to a gut-friendly diet may help prevent or manage cholesterol issues over months and years.

Want to Apply This Research?

  • Track daily servings of gut-friendly foods: whole grains, vegetables, fruits, legumes, nuts, and seeds. Aim for at least 5 servings of vegetables and fruits daily, 3 servings of whole grains, and 1-2 servings of legumes or nuts. Log these in your app and monitor your weekly totals.
  • Start by adding one gut-friendly food to each meal this week. For example: add berries to breakfast, include a side salad at lunch, and add beans to dinner. Use the app to set daily reminders to include these foods and track your progress toward weekly goals.
  • Create a monthly check-in where you review your average daily gut-friendly food servings and note any changes in how you feel (energy levels, digestion). If you have access to cholesterol testing, track results every 3-6 months to see if dietary improvements correlate with better cholesterol levels. Use the app’s trending feature to visualize improvements over time.

This research shows an association between gut-friendly diets and lower cholesterol risk but does not prove that diet changes will prevent or treat high cholesterol in all individuals. If you have high cholesterol, are taking cholesterol-lowering medications, or have a history of heart disease, consult with your healthcare provider before making significant dietary changes. Do not stop taking prescribed medications without medical guidance. Individual responses to dietary changes vary based on genetics, overall health status, and other factors. This information is for educational purposes and should not replace professional medical advice.