Assessing Myths of Animal-Based Foods: Effects on Inflammation and Disease

Image of a chalkboard with wording Inflammation and a red stethoscope to the right of it by Katie Petit for the Inflammation and Animal Fats post for The Healthy RD
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Written by Katie Petit, RDN

Inflammation

Inflammation is the body’s innate immune response to injury, illness, or infection and is an essential step in the healing process.1 In acute inflammation, there is warm, red and swollen skin surrounding inflamed, injured tissue, and in response, the body deploys cytokines, which include various types of proteins that act as messengers to alert and direct immune cells to fight the foreign invaders causing the illness or infection.2 Although inflammation is an integral part of the healing process, prolonged inflammation, or chronic inflammation, poses a threat to our health. Inflammation can turn from acute to chronic when the infected site does not heal efficiently. This chronic inflammation can persist for months or even years, affecting nearly every system in the body and causing harm to previously healthy cells and organ systems.1-3 Chronic inflammation is an underlying factor of many diseases including autoimmune conditions, neurological conditions, cardiovascular disease, type 2 diabetes, cancer, liver diseases and kidney diseases.4 Nutrition interventions present as an essential solution for reducing chronic inflammation, and today, we will look specifically at links between diet and inflammation and cardiovascular health.

Plant-Based: Hot Topic

Image of plant-based meats of various kinds including fake chicken, fake meats, also known as plant-based meats by Katie Petit for The Healthy RD

In recent years, plant-based or plant-forward diets have dominated the media and wellness world, growing in popularity as a proposed solution for living a more environmentally conscious and healthful life. People embrace this eating pattern for a variety of reasons – perhaps they’ve learned it can reduce their environmental footprint and promote animal welfare, or more closely emulate the Mediterranean diet, which has been touted for its numerous health benefits including its promotion of longevity, and reduction of non-communicable diseases and inflammation.5-10 Defining characteristics of the Mediterranean diet include prioritization of consuming whole foods such as whole grains, fruits and vegetables, heart-healthy fats such as omega-3 fatty acids from fish, extra virgin olive oil and avocadoes, and consuming meat and dairy in moderation. While whole grains get the green light for health, for a lot of people, sensitivities to antinutrients and gluten can cause inflammation instead of prevent it too.

It’s true that incorporating more plants such as fruits, vegetables, and whole grains provides fiber and health-boosting and protective nutrients such as vitamins, minerals, and phytochemicals. However, with the push towards adopting a plant-dominated diet and limiting animal products to reduce inflammation and promote overall health, what are the facts about animal-based whole foods, such as beef and dairy?

Animal Products and Saturated Fats

With the push for more plant-based eating and the Mediterranean diet to combat inflammation, as polyunsaturated fats from sources such as fish, avocadoes and olive oil reduce inflammation and promote heart health, highly nutritious animal-based foods containing saturated fats have been cast aside. Saturated fats are an essential source of dietary fat and energy found mainly in animal-based foods such as meat and dairy and plant-based foods like coconut and tropical oils.

Intake of saturated fats has been cautioned for decades, notably since Ancel Keys’ lipid hypothesis of the 1950s.11,12 Ancel Keys theorized that a direct relationship exists between the amount of dietary saturated fat and cholesterol and incidence of coronary heart disease.11 This theory was based on observational study findings and coined as the “diet-heart hypothesis,” and has played an influential role in shaping guidelines from prominent health organizations such as the American Heart Association and the U.S. Departments of Agriculture and Health and their Dietary Guidelines for Americans.13

Since the theory’s inception decades ago, dietary intake of saturated fat has been a point of contention and questioning in the world of nutrition.11-14 In recent decades, researchers have brought to light newfound evidence that challenges Keys’ theory.

Red Meat and Inflammation

Image of fresh red meats for the post about animal-based diet and inflammation by Katie Petit RD for The Healthy RD

Inflammation is one perpetrator of cardiovascular disease, and red meat has been reportedly linked to inflammation and cardiovascular disease development, due to its saturated fat content and subsequent potential to raise low-density lipoprotein (LDL) cholesterol, or “bad” cholesterol.15,16 A study published in The American Journal of Clinical Nutrition investigated the connection between intake of red meat and inflammation. Data was gathered from older US adults who participated in the MultiEthnic Study of Atherosclerosis. Researchers analyzed self-reported dietary intake among participants as well as metabolomic data, meaning that they analyzed metabolites, which are substances resulting secondary to the digestion of food.17 Plasma metabolites from the collected data were assessed to identify links between metabolites from red meat and inflammation. When researchers adjusted for BMI in their resulting data, assessing the data independent of weight, neither unprocessed nor processed red meat consumption was associated with inflammatory markers, including C-reactive protein. The study’s findings revealed that body weight, rather than dietary intake of red meat, is a factor related to inflammation.18,19 Independent from weight, consumption of red meat does not affect inflammation, contrary to what we often read in circulating headlines in the media!

Red Meat and Cardiovascular Disease

The advice on red meat intake has long been to minimize intake to as little as possible (or better yet, none!) There is research out there that both supports and disputes a link between red meat and adverse cardiac outcomes. Researchers from The Cochrane Heart Group conducted a systematic review and meta-analysis of 15 randomized controlled trials to assess the effects of reducing saturated fat intake on health outcomes including cardiovascular morbidity and all-cause mortality. With this, researchers considered the effects on health outcomes when energy from saturated fats was replaced with carbohydrates, unsaturated fats, and/or protein. Findings revealed that reduction of total saturated fat intake may reduce risk for cardiovascular disease, including strokes and heart disease, by roughly 17%. As for the replacement groups, replacing dietary saturated fat with polyunsaturated fat resulted in a 21% reduction in risk for cardiovascular events, and replacing saturated fats with carbohydrates yielded a 16% reduction in risk for cardiovascular events, and other replacements yielded little to no effect. Although researchers identified health benefits from incorporating polyunsaturated fats and complex carbohydrates into the diet, the risk for suffering from cardiovascular events was not vastly different among the groups.20

Dairy and Inflammation

Image of colby jack cheese heart cutouts on a wooden cutting board for the Inflammation and Animal Fats by Katie Petit RD for The Healthy RD

Dairy garners mixed reviews – some believe it to be an inflammatory food, while others have no issue with dairy products. Nonetheless, opting for plant-based milk rather than cow milk has become quite the trend. For those with an allergy to casein, a protein found in milk, consumption of dairy yields an inflammatory response which may range from mild to life-threatening, so plant-based options are suitable.21 A good portion of the world’s population, an estimated 68%, experiences lactose intolerance, commonly developed after infancy. However, goat milk is thought suitable for those with a cow milk allergy or who are lactose-intolerance, due to its differing protein profile and reduced lactose content.22,23

Aside from those with allergies and intolerances, cow milk is appropriate for most people and is beneficial for human health.21 Dairy products are a rich source of saturated fat, which explains its assumed association with inflammation and why the current guidelines recommend the consumption of low-fat or fat-free dairy. Recent evidence challenges current dietary guidelines for saturated fat intake, which is advised to comprise less than 10% of total daily calories. A review published in the journal of Critical Reviews in Food Science and Nutrition in 2017 revealed some weak but significant evidence according to researchers, illuminating anti-inflammatory properties of dairy. These findings challenge prior beliefs about the relationship between saturated fat and inflammation.25 Consuming fermented dairy products with live active cultures such as kefir or yogurt promote a flourishing gut microbiome which may reduce inflammation.21

Dairy and Cardiovascular Disease

Image of various dairy products including blue cheese, cotija cheese, brie, cheddar, mozzerella, swiss cheese, milk, and yogurt on a cutting board for the animal fats and inflammation post by Katie Petit RD for The Healthy RD

For the same reason that red meat intake is cautioned, especially in those at greater risk for developing heart disease, low-fat dairy products are recommended over any others, as they contain a reduced amount of saturated fat when compared to full-fat options, with the intention being that saturated fat increases LDL cholesterol and subsequent risk for cardiovascular conditions such as atherosclerosis.26

A recent randomized controlled trial published in the American Journal of Clinical Nutrition explored the impacts of dairy foods with complex food matrices on the serum lipid profiles and other cardiovascular disease risk factors in 66 weight-stable patients with metabolic syndrome. Initially, participants completed a 4-week trial in which they followed a limited-dairy diet, consuming a maximum of 3 servings of nonfat milk/week. Then, participants were randomly assigned to continue the limited-dairy diet or follow either a low-fat (consuming 3.3 servings of dairy daily through nonfat milk, yogurt or nonfat cheese) or full-fat dairy (consuming 3.3 servings of dairy daily through 3.25% whole milk, 3.1% yogurt and full-fat cheese) diet for 12 weeks. The researchers administered 3.3 servings to ensure that participants who consumed 90% of those daily servings met the recommendations from the 2015 Dietary Guidelines for Americans, which was to consume at least 3 servings of dairy daily.26

Researchers found that there was no impact on fasting serum lipids including total, LDL, and HDL cholesterol, triglycerides and free fatty acids across all interventions. They also observed no effects of interventions on diastolic blood pressure, but they did observe a significant difference among interventions for systolic blood pressure, with a trend of decreasing systolic values in the low-fat dairy group compared with the limited dairy group. Based on their findings, researchers suggest that increased amounts of dairy fat consumed daily through whole foods with complex matrices do not have adverse effects on fasting serum lipid levels, and are not associated with cardiovascular risk, as is commonly believed!26

Conclusions

As noncommunicable diseases, such as cardiovascular disease, cancer, diabetes and respiratory disease, are leading causes of death worldwide, it is essential to consider and evaluate nutrition’s role in disease prevention and health promotion. Research of the recent decade challenges long-held beliefs surrounding saturated fat, inflammation and disease risk. Findings point to the importance of considering whole foods with complex matrices, comprised of micronutrients, macronutrients and other bioactive compounds essential for human health, rather than targeting single foods and nutrients.27

References

  1. Cleveland Clinic. Inflammation. March 22, 2024. https://my.clevelandclinic.org/health/symptoms/21660-inflammation
  2. Cleveland Clinic. Cytokines. January 3, 2023. https://my.clevelandclinic.org/health/body/24585-cytokines
  3. Yale Medicine. How Inflammation Affects Your Health. April 8, 2022. https://www.yalemedicine.org/news/how-inflammation-affects-your-health
  4. Furman D, Campisi J, Verdin E, et al. Chronic inflammation in the etiology of disease across the life span. Nat Med. 2019;25(12):1822-1832. doi:10.1038/s41591-019-0675-0
  5. United Nations. Your guide to climate action: Food. https://www.un.org/en/actnow/food#:~:text=Switching%20to%20a%20plant-based,for%20a%20particular%20meal(ex
  6. Animal Aid. Going vegan for the animals. https://www.animalaid.org.uk/veganism/why-veganism/going-vegan-animals/#:~:text=Going%20vegan%20is%20one%20of,on%20farms%20and%20in%20slaughterhouses
  7. Mayer, BA. 8 Ways the Mediterranean Diet Can Help You Live a Longer and Healthier Life. Healthline. April 25, 2023. https://www.healthline.com/health-news/8-ways-the-mediterranean-diet-can-help-you-live-a-longer-and-healthier-life
  8. Tepper S, Kissinger M, Avital K, Shahar DR. The Environmental Footprint Associated With the Mediterranean Diet, EAT-Lancet Diet, and the Sustainable Healthy Diet Index: A Population-Based Study. Front Nutr. 2022;9:870883. May 19, 2022. doi:10.3389/fnut.2022.870883
  9. McManus KD. What is a plant-based diet and why should you try it? Harvard Health Blog. March 28, 2024. https://www.health.harvard.edu/blog/what-is-a-plant-based-diet-and-why-should-you-try-it-2018092614760
  10. Alcorta A, Porta A, Tárrega A, Alvarez MD, Vaquero MP. Foods for Plant-Based Diets: Challenges and Innovations. Foods. 2021;10(2):293. February 1, 2021. doi:10.3390/foods10020293
  11. Fallon S, Enig MG. Nourishing Traditions. 2nd ed. NewTrends Publishing, Inc; 2001.
  12. Bjarnadottir A. 5 Studies on Saturated Fat – Time to Retire the Myth? Healthline. June 23, 2023. https://www.healthline.com/nutrition/5-studies-on-saturated-fat
  13. Astrup A, Teicholz N, Magkos F, et al. Dietary Saturated Fats and Health: Are the U.S. Guidelines Evidence-Based? Nutrients. 2021;13(10):3305. September 22, 2021. doi:10.3390/nu13103305
  14. Forouhi NG, Krauss RM, Taubes G, Willett W. Dietary fat and cardiometabolic health: evidence, controversies, and consensus for guidance. BMJ. 2018;361:k2139. June 13, 2018. doi:10.1136/bmj.k2139
  15. Cleveland Clinic. 5 Types of Foods That Cause Inflammation. https://health.clevelandclinic.org/foods-that-can-cause-inflammation
  16. Bandeira Silva de Medeiros GC, Morais de Azevedo KP, Mesquita Barbalho Xavier G, et al. Red meat consumption, risk of incidence of cardiovascular disease and cardiovascular mortality, and the dose-response effect. Medicine (Baltimore). 2019;98(38):e17271. doi:10.1097/MD.0000000000017271
  17. National Institute of Health. Dictionary of Cancer Terms. National Institute of Health: National Cancer Institute. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/metabolite
  18. Wood AC, Graca G, Gadgil M, Senn MK, et al. Untargeted metabolic analysis investigating links between unprocessed red meat intake and markers of inflammation. The American Journal of Clinical Nutrition. 2023;118(5):989-999. https://doi.org/10.1016/j.ajcnut.2023.08.018
  19. Baylor College of Medicine. Is red meat intake linked to inflammation? EurekAlert! October 26, 2023. https://www.eurekalert.org/news-releases/1006096
  20. Hooper L, Martin N, Jimoh OF, Kirk C, Foster E, Abdelhamid A. Reduction in saturated fat intake for cardiovascular disease risk. Cochrane Database Syst Rev. 2020;8(8):CD011737. August 21, 2020. doi:10.1002/14651858.CD011737.pub3
  21. Williams C. Does Dairy Cause Inflammation? Here’s What a Dietitian Says. EatingWell. November 30, 2022. https://www.eatingwell.com/article/2056066/heres-what-a-dietitian-says-about-dairy-causing-inflammation/#:~:text=Even%20when%20the%20reaction%20is,little%20in%20regard%20to%20inflammation.
  22. National Institute of Diabetes and Digestive and Kidney Diseases. Definitions & Facts for Lactose Intolerance. February 2018. https://www.niddk.nih.gov/health-information/digestive-diseases/lactose-intolerance/definition-facts#:~:text=While%20most%20infants%20can%20digest,world’s%20population%20has%20lactose%20malabsorption.&text=Lactose%20malabsorption%20is%20more%20common,the%20world%20than%20in%20others.
  23. Malik TF, Panuganti KK. Lactose Intolerance. National Library of Medicine: National Center for Biotechnology Information. April 17, 2023. https://www.ncbi.nlm.nih.gov/books/NBK532285/
  24. Metzger M. Goat milk versus cow milk: a comparison. Michigan State University Extension. July 22, 2022. https://www.canr.msu.edu/news/goat-milk-versus-cow-milk-a-comparison#:~:text=Additionally%2C%20many%20people%20that%20have,and%20different%20forms%20of%20proteins.
  25. Bordoni A, Danesi F, Dardevet D, et al. Dairy products and inflammation: a review of the clinical evidence. Critical Reviews in Food Science and Nutrition. 2017;57(12):2497-2525. https://doi.org/10.1080/10408398.2014.967385
  26. Schmidt KA, Cromer G, Burhans MS, et al. Impact of low-fat and full-fat dairy foods on fasting lipid profile and blood pressure: exploratory endpoints of a randomized controlled trial. The American Journal of Clinical Nutrition. 2021;114(3):882-892. https://doi.org/10.1093/ajcn/nqab131
  27. Miller GD, Ragalie-Carr J, Torres-Gonzalez M. Perspective: Seeing the Forest Through the Trees: The Importance of Food Matrix in Diet Quality and Human Health. Adv Nutr. 2023;14(3):363-365. 10.1016/j.advnut.2023.03.005

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