Is a diverse diet really better for your health?

There has been the long-standing public health recommendation to consume a variety of foods. This stems from the 20th century where, it was recognised that foods we ate (or didn’t) directly correlated to the prevalence of nutritional inadequacies (de Oliveira Otto et al 2018).

This recommendation was made on the premise that more variety in one’s diet, will ultimately lead to optimal health outcomes. What’s important to note with this recommendation is that it never defined what is meant by ‘food diversity’, leading to impressionistic views on what a ‘varied diet' looks like (de Oliveira Otto et al 2018).

In the last five years, research has looked at what ‘food diversity’ means comprehensively. Literature searches of observational studies revealed that those that believed they consumed a ‘diverse diet’ meant that their intakes of processed foods, sweetened beverages, refined grains were in fact higher, and their intake of fruit, vegetables, water and fish were suboptimal. Higher rates of poor food relationships, obesity and subsequent comorbidities were also observed (de Oliveira Otto et al 2018).

Moreover, newer research from the American Gut Project from the University of California analised the diversity of human microbiomes as well as collecting data on their heredity, dietary and lifestyle factors from participants in the United States, Australia, United Kingdom and 42 other countries.

The number of plant varieties in a person’s diet (regardless of the diet they prescribe to eg. vegan, vegetarian etc) is the largest determinant of the number of strains of beneficial bacteria in the gut microbiome, and, have identified that consuming thirty or more different types of plant foods per week increases the biodiversity of their microbiome.

What does our microbiome do?

The resident bacteria, fungi and yeast, feed on non-digestible fibres (naturally found in plant foods) to produce short chain fatty acids (SCFAs) butyrate, proprionate and acetate each offering a different beneficial service to our gastrointestinal system; butyrate provides the energy for our colonocytes, inhibits cancer cell production, maintains intestinal integrity (therefore reducing permeability) and is anti-inflammatory (Valdes et al., 2018). Propionate is mainly involved with glucose production in the liver and small intestine. Acetate is essential for the growth of other beneficial bacteria as well as cholesterol regulation and fatty acid synthesis. Both butyrate and propionate are involved with gut hormone signalling (satiety) and help to lower diet related obesity and insulin resistance (valdes et al., 2018). Whilst each SCFA plays a different role, each are just as important as one other, therefore consuming a wide variety of plant foods, ensures a balanced production of SCFAs (University of California, 2018).

What does this mean for our health?

Lower microbiome diversity has been observed in patients with inflammatory bowel disease, immune dysregulation & frequent infections, atopic eczema, food allergies, psoriatic arthritis, obesity, coeliac disease, type 1 & 2 diabetes, arterial stiffness and in smokers than in healthy controls (Nance et al., 2020).

Observations have also been made with the microbiome and mental health. Participants with a reported mental health disorder such as depression, bipolar disorder, post-traumatic stress disorder and schizophrenia all had similar bacterial make up in their gut when compared with their mentally healthy pairs who had very diverse microbiomes (University of California, 2018).

Another study explored cognitive function and gut microbiomes. They too, identified that greater microbial diversity reflected higher cognitive functions in middle aged women and men (Meyer et al, 2021).

The American gut project reported that participants who consumed thirty or more plant foods per week, also had fewer antibiotic resistant genes in their gut which also meant that their resident bacteria ward off the bacterial strains usually requiring antibiotics thus, fewer antibiotics were taken by this participant group.

How can you include more plant diversity in your diet?

Let’s break down thirty plant foods in a week which is just over four plant foods per day. Completely doable right? You might like to try a new vegetable or fruit each time you shop, you could sprinkle some seeds on top of your meals, add in some extra herbs to your cooking, aim to eat a rainbow of plant foods each day, reach for whole grains instead of processed, replace one meat meal per week for a legume based meal. These are just a few suggestions and of course may not work for everyone. If you have any specific health concerns and would like an in depth holistic assessment with a tailored treatment plan, please feel free to book an intial consult or book a free discovery zoom call to chat, I would love to help you!

References

Deleu, S., Machiels, K., Raes, J., Verbenke, K. and Vermeire, S. Short chain fatty acids and its producing organisms: An overlooked therapy for IBD? eBioMedicine, Volume 66, 103293. https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(21)00086-4/fulltext

Marcia C. de Oliveira Otto., Anderson, A., Dearborn, J.,Ferranti, E., Mozaffarian, D., Rao,G., Wylie-Rosett, J., Alice H (2019). LichtensteinDietary Diversity: Implications for Obesity Prevention in Adult Populations: A Science Advisory From the American Heart Association. PMC. doi: 10.1161/CIR.0000000000000595

Meyer K, Lulla A, Debroy K, et al. Association of the Gut Microbiota With Cognitive Function in Midlife. JAMA Netw Open. 2022;5(2):e2143941. doi:10.1001/jamanetworkopen.2021.43941

Nance, C. L., Deniskin, R., Diaz, V. C., Paul, M., Anvari, S., & Anagnostou, A. (2020). The Role of the Microbiome in Food Allergy: A Review. Children (Basel, Switzerland), 7(6), 50. https://doi.org/10.3390/children7060050

University of California - San Diego. (2018, May 15). Big data from world's largest citizen science microbiome project serves food for thought: How factors such as diet, antibiotics and mental health status can influence the microbial and molecular makeup of your gut. ScienceDaily. www.sciencedaily.com/releases/2018/05/180515092931.htm