Heart Health and the Gut Microbiome
Is Heart Health as Simple as What We Eat?
The current mortality statistics for cardiovascular disease (CVD) in the United States (US) and on a global scale are staggering. CVD is responsible for approximately 31% of global deaths,1 and approximately 25% of adults in the United States (US) have CVD.2 The American Heart Association has identified eight primary measures for improving and maintaining cardiovascular health: Life’s Essential 8.3 However, a lesser recognized measure that has a profound effect on cardiovascular health has recently emerged,4-5 that of the gut microbiome. The link between cardiovascular health and diet is not merely due to essential nutrients found in food but is highly related to the complex community of gut microbes.
It is well established that the gut microbiome is important for immune system function as well as food digestion and absorption, and yields thousands of enzymes, hormones, vitamins, and metabolites necessary for overall health.4 But what is the connection between heart health and the gut microbiome? It turns out that gut microbes are also associated with circulating vascular chemicals that influence the atherosclerotic6 process, appetite hormones, glucose regulation, and inflammation—thereby impacting the risk for obesity and type 2 diabetes and, ultimately, CVD. Although many of the mechanisms involved in the specific relationships between the gut microbiome and cardiovascular health5 are relatively recent findings, during the last two decades a progressively greater emphasis has been placed on understanding the complexity of gut microbes and the internal and external effects in the intestine and overall system.4-7
The Scientific Relationship Between Heart Health and Gut Microbiome
The gut microbiome may be much more complex than initially theorized. A recent study by Asnicar et al. demonstrated the importance of the beneficial gut microbes to harmful microbes in 1,100 individuals in Britain and the US.7 The ’good’ gut microbes protect against CVD, obesity, and diabetes, counteracting the ‘bad’ microbes that promote inflammation, heart disease, and poor metabolic health.
In addition, in animals and humans alike, the gut microbiome may change, depending on certain conditions like age, physical activity engagement, and overall health status.8 Changes in health behavior influence gut health and have implications for cardiovascular health; they are interrelated.
No two microbiomes are the same. On average, individuals share about 30 percent of gut bacterial species; therefore, what is healthy for one person may not be healthy for another.8
Aging, Indoles, and Cardiovascular Disease
In more closely examining the microbiome of over 9,000 individuals aged 18 to 101 years, Wilmanski and colleagues8 observed changes in the microbiome beginning at about age 40 such that the dominant strains declined, and less dominant strains increased. Those with the greatest change in their microbiome were healthier, lived longer, had higher Vitamin D levels, took fewer medications, had lower cholesterol and triglyceride levels, and had faster walking speeds with greater mobility.
Other researchers identified higher levels of a metabolite known as an indole or Indole-3-Propionic Acid. This is a type of phytochemical found in plants and in certain vegetables such as broccoli, cabbage, and cauliflower.9 Xue et al. recently demonstrated the link among disorders in the gut microbiota, indoles, and CVD.10 Indoles are associated with youthfulness, increased mobility, and physical activity engagement; decreased inflammation; staving off sickness, injuries, and the stress that occurs with aging, as well as inhibiting atherosclerosis.8
A Diet to Improve the Microbiome
When considering how to improve microbiome health through diet, research demonstrates,11 that ample quantities of fiber and plant foods (beans, nuts, seeds, and vegetables) improve the microbiome, but a diet largely comprised of highly processed foods, empty carbohydrates, and glucose, and lacking in fiber, vitamins, and minerals, is not beneficial for microbiome health.
Four Strategies for Improving the Microbiome
1. Embracing a diet with diverse food sources
The diversity of the gut microbiome is linked to the foods we eat—and consumption of a diet with a variety of whole foods, rather than processed or non-whole foods, which can positively impact health. It is estimated that 75% of the world’s food is produced from only 12 species of plants and 5 animal species.12 Eating new and different foods can be an important source of supporting our gut and overall health.
2. Eating a ‘colorful’ diet
Fruits and vegetables are the best sources of nutrients for a healthy microbiome. They provide a rich source of fiber, which cannot be digested by the human body but provide a food source for our gut bacteria. Examples include raspberries, artichokes, green peas, broccoli, chickpeas, lentils, beans, whole grains, bananas, and apples.
3. Ingesting Probiotics
Most may be familiar with the role of a probiotic, those living microorganisms that promote the growth of beneficial bacteria in the gut. Examples of good bacteria include Lactobacillus, Lactococcus, Streptococcus, Bifidobacterium, and also mold and yeast.13 Present in fermented foods which are a rich source of probiotics, or cultured milk, they reside in the gut yet improve immune system function and benefit heart health. Research indicates that probiotics prevent hypertension and high cholesterol in addition to certain GI diseases to name a few. With their vast immune system benefits, many implications exist for the use of probiotics as a substitute for antibiotics or even anti-inflammatory drugs.
4. Reduce or eliminate sugar and processed foods
Monosaccharides such as glucose and fructose are digested so quickly that the gut bacteria don’t get any nutrition from them.14 Focusing on more complex sugars from sources such as sweet potatoes, bananas, berries, and apples provides diversity in your diet and healthy food sources for your microbiome.
Exercise and the Microbiome
In addition to diet, improved life expectancy is associated with a strong connection to friends and family, a sense of purpose, a positive outlook on life, and engaging in adequate quantities of physical activity.14 Consider, for example, the centenarians who spend ample time outdoors, gardening, farming, and even socializing with their community.14
However, researchers have also identified a strong association between gut health and longevity,15 as well as gut health and implications for cardiovascular benefits, in marathon runners.16 In a study by Scheiman and colleagues,16 marathon runners had a greater number of the bacteria Veillonella. Before a marathon, their Veillonella count was higher than sedentary individuals, but after completing it, the Veillonella count in runners soared.
It turns out that Veillonella metabolizes lactate, a byproduct of anaerobic metabolism.16 Lactate levels increase after exercise due to muscle metabolism. The lactate then travels to the blood, is sent to the gut, and is then metabolized by microbes. Lactate is broken down into several substances, one of which is propionate: propionate influences glucose metabolism, oxygen consumption, and inflammation in muscles. The combination of Veillonella, along with the increased production of gut propionate, has important implications for cardiovascular health by decreasing inflammation, preventing atherosclerotic risk, and improving insulin resistance.
Clinical Takeaways for Heart Health and the Gut Microbiome
The vast amount of evidence emerging in recent decades to further understand the complexity of the gut microbiome not only demonstrates its significance to cardiovascular health5 but offers insight into prevention and treatment strategies for the ongoing global health problem of CVD. It is important for cardiovascular nurses to understand the relationship between heart health and gut microbiome, for both informing patient education strategies that are incorporated into clinical care and for future research endeavors. Additional research is warranted due to the heterogeneity of findings associated with the gut microbiome;10 however, it is certain that what happens in the gut does not just stay in the gut.
- World Health Organization. WHO, 2023. Cardiovascular diseases: Symptoms & treatment. https://www.who.int/health-topics/cardiovascular-diseases#tab=tab_1
- Centers for Disease Control and Prevention. National center for chronic disease prevention and health promotion, division for heart disease and stroke prevention. Last Reviewed: October 14, 2022 https://www.cdc.gov/heartdisease/facts.htm
- Lloyd-Jones DM, Allen NB, Anderson CAM, et al. Life’s Essential 8: Updating and enhancing the American Heart Association’s construct of cardiovascular health: A presidential advisory from the American Heart Association. Circulation. 2022;146(5):e18-e43. doi:10.1161/CIR.0000000000001078
- Valdes AM, Walter J, Segal E, Spector TD. Role of the gut microbiota in nutrition and health. BMJ. 2018;361:k2179. Published 2018 Jun 13. doi:10.1136/bmj.k2179
- Rahman MM, Islam F, -Or-Rashid MH, et al. The gut microbiota (microbiome) in cardiovascular disease and its therapeutic regulation. Front Cell Infect Microbiol. 2022;12:903570. Published 2022 Jun 20. doi:10.3389/fcimb.2022.903570
- Zhu Y, Li Q, Jiang H. Gut microbiota in atherosclerosis: focus on trimethylamine N-oxide. APMIS. 2020;128(5):353-366. doi:10.1111/apm.13038
- Asnicar F, Berry SE, Valdes AM, et al. Microbiome connections with host metabolism and habitual diet from 1,098 deeply phenotyped individuals. Nat Med. 2021;27(2):321-332. doi:10.1038/s41591-020-01183-8
- Wilmanski T, Diener C, Rappaport N, et al. Gut microbiome pattern reflects healthy ageing and predicts survival in humans [published correction appears in Nat Metab. 2021 Apr;3(4):586]. Nat Metab. 2021;3(2):274-286. doi:10.1038/s42255-021-00348-0
- Li X, Zhang B, Hu Y, Zhao Y. New insights into gut-bacteria-derived indole and its derivatives in intestinal and liver diseases. Front Pharmacol. 2021;12:769501. doi:10.3389/fphar.2021.769501
- Xue H, Chen X, Yu C, et al. Gut microbially produced indole-3-propionic acid inhibits atherosclerosis by promoting reverse cholesterol transport and its deficiency is causally related to atherosclerotic cardiovascular disease. Circ Res. 2022;131(5):404-420. doi:10.1161/CIRCRESAHA.122.321253
- Gardner CD, Trepanowski JF, Del Gobbo LC, et al. Effect of low-fat vs low-carbohydrate diet on 12-month weight loss in overweight adults and the association with genotype pattern or insulin secretion: The DIETFITS randomized clinical trial [published correction appears in JAMA. 2018 Apr 3;319(13):1386] [published correction appears in JAMA. 2018 Apr 24;319(16):1728]. JAMA. 2018;319(7):667-679. doi:10.1001/jama.2018.0245
- Heiman ML, Greenway FL. A healthy gastrointestinal microbiome is dependent on dietary diversity. Mol Metab. 2016;5(5):317-320. Doi: 10.1016/j.molmet.2016.02.005.
- Zaib S, Hayat A, Khan I. Probiotics and their beneficial health effects [published online ahead of print, 2023 Jun 8]. Mini Rev Med Chem. 2023;10.2174/1389557523666230608163823. doi:10.2174/1389557523666230608163823
- Hills RD Jr, Pontefract BA, Mishcon HR, Black CA, Sutton SC, Theberge CR. Gut Microbiome: Profound Implications for Diet and Disease. Nutrients. 2019;11(7):1613. Published 2019 Jul 16. doi:10.3390/nu11071613
- Gagnon E, Mitchell PL, Manikpurage HD, et al. Impact of the gut microbiota and associated metabolites on cardiometabolic traits, chronic diseases and human longevity: a Mendelian randomization study. J Transl Med. 2023;21(1):60. Published 2023 Jan 30. doi:10.1186/s12967-022-03799-5
- Scheiman J, Luber JM, Chavkin TA, et al. Meta-omics analysis of elite athletes identifies a performance-enhancing microbe that functions via lactate metabolism. Nat Med. 2019;25(7):1104-1109. doi:10.1038/s41591-019-0485-4