Aging and a high-fat diet wreak havoc on microflora and result in inflammation in heart failure.The connection between a high-fat diet, aging, and risk for diabetes and other chronic problems is well known. However, information is now coming to light that indicates that these factors may also impact the immune system. Researchers in Alabama are studying how a high-calorie diet enriched with omega-6 fatty acids affect the gut microbiome and risk for heart failure (1).Using a mouse model, Dr. Ganesh Halade, Ph.D., and his team at the University of Alabama and other research facilities studied how aging and an obesity-generating omega-6-enriched diet affect gut microflora, the structure and function of the spleen, and immune response to a heart attack.Halade’s study, featured in FASEB Journal, found that a high-calorie, obesity-generating diet in elderly mice destroyed the makeup of the gut microbiome. This was associated with the development of a non-resolving, systemic inflammation in acute heart failure with an impact on the immune cell profile including the neutrophil-leukocyte ratio. (Halade is an associate professor in the Division of Cardiovascular Disease, UAB Department of Medicine).

Scientists recognize that the foods we eat interact with gut microbes to moderate the body’s immune system. This concept was examined further with this exploration of aging and high-fat diet. The scientists discovered that the obesity-generating diet increased the production of bacteria Allobaculum phylum Firmicutes. This type of diet also raised the neutrophil content in the blood of young mice. A similar increase in proportion of neutrophils was seen for both old mice fed a standard diet and old mice fed the obesity-generating diet.

Leukocytes that get released after heart injury are housed in the spleen, a secondary immune organ. Splenic leukocytes transfer to the heart to start tissue repair and reduce inflammation.After a heart attack, Halade and researchers discovered that the obesity-generating diet and aging resulted in neutrophil collecting and a changed leukocyte profile. Splenic structural deformities were also seen in the mice with a drop in splenic CD169-positive macrophages.Young mice that consumed the obesity-generating diet were able to reverse inflammation post-heart attack, despite their gut microflora being altered by the high-fat diet. Older mice on the obesity-generating diet, by comparison, experienced non-resolving inflammation as the result of the heart attack. This inflammation is linked to heart failure.According to Halade, "The data strongly indicate that the obesity-generating diet develops an inflammatory microenvironment, even in young mice, that amplifies with aging, This study highlights that diet and age are critical factors that have a differential impact with age, and it highlights the spleen and heart as an inter-organ communication system with the immune defense system."While this study was conducted in mice, there are important points to be made in regard to our client’s diets.

• A high-calorie, obesity-generating diet is associated with an increased risk of heart disease (2).
• Advising clients to choose nutrient-dense foods that help prevent weight gain is a prudent idea.
• The consumption of high-fat foods containing omega-6 fatty acids and their impact on inflammation is not well understood, with some studies showing that omega-6 containing foods may have anti-inflammatory properties. Foods containing both omega-3 and omega-6 fatty acids (fatty fish, vegetable oil, nuts, and seeds, avocados) may both be beneficial in reducing inflammation (3).
• Keep in mind, there are multiple factors that impact our gut microbiome including fiber intake, probiotic intake, antibiotic use, and stress.
• While we cannot control aging, we can, to some extent, control what we put in our mouths.

By Lisa Andrews, MEd, RD, LDReferences:

1. Vasundhara Kain, William Van Der Pol, Nithya Mariappan, Aftab Ahmad, Peter Eipers, Deanna L. Gibson, Cecile Gladine, Claire Vigor, Thierry Durand, Casey Morrow, Ganesh V. Halade. Obesogenic diet in aging mice disrupts gut microbe composition and alters neutrophil:lymphocyte ratio, leading to inflamed milieu in acute heart failure. The FASEB Journal, 2019; fj.201802477R DOI: 10.1096/fj.201802477R
2. https://www.medicalnewstoday.com/articles/321382.php
3. Innes JK1, Calder PC2. Omega-6 fatty acids and inflammation. Prostaglandins Leukot Essent Fatty Acids. 2018 May;132:41-48.