Title: Importance of Food Diversity in Gut Health

Importance of Food Diversity in Gut Health

What is Food Diversity?

Food diversity can mean a few things. It can refer to cultural diversity in the foods we eat and the traditions we have around foods. Or it can refer to the number of different foods we eat. While I love to explore and eat various cultural cuisines, here we will discuss the importance of food diversity as it relates to the variety of foods in your diet. We will discuss how this translates to good gut health, and good health in general.

Food Diversity for Microbial Diversity

Microbes

Microbiota vs Microbiome

First, let’s get a few definitions out of the way. The term microbiota refers to the various microorganisms, including bacteria, viruses, and fungi, that live in a particular environment. A microbiome includes the microbiota, their genes, and the environment in which they live.1 

There are several microbiomes on and in the human body. These include the skin, mouth, nose, vagina, and even the lungs. These microbiomes and the microbiota within it are being studied for their impact on human health. Scientists are also exploring what factors help or harm the microbiome, such as genetics, environment, medications, illness, diet, and lifestyle.

In this article, we focus on the gut microbiome which is probably what most people are talking about when they throw around the general term “microbiome”.

The American Gut Project

The American Gut Project is a large ongoing population study where “citizen scientists” submit a stool sample to be analyzed for microbes. Anyone can be a “citizen scientist” by purchasing a home sample kit. In return for their investment and ahh, deposit…  they get an individual report on their microbiome.

So far in this project researchers have found that people who eat a large variety of plant foods have greater diversity of bacteria in poop.2 This is important because diversity in gut bacteria is thought to be associated with good health.

Specifically, they compared individuals who consumed more than 30 types of plant foods per week vs those who consumed 10 plant foods or less. In addition to increased microbial diversity, those who consumed more plants had higher amounts of short chain fatty acids (SCFA) and other healthful compounds in their poop.

SCFA are byproducts of bacterial fermentation and serve as a source of fuel for cells in the colon. SCFA may provide many health benefits including improvements in weight, inflammation, blood pressure, and overall heart health3. They also play a role in maintaining the gut barrier to prevent bacteria from crossing cell walls, which may reduce inflammation and infections.

The American Gut Project has some weaknesses in its study design. Randomized controlled trials are considered the highest quality studies. The American Gut Project is a lower quality type of study – a population study.

In this study, subjects were volunteers who paid a fee to participate. This likely resulted in under-representation of certain groups. However, the study still provides valuable information on what might be important for a healthy gut microbiome. And despite the study’s weaknesses, most health experts would agree that adding more plant foods to your diet is never a bad idea.

What Makes Plants So Special?

Plants contain fiber. Fiber is found in the cell walls of plants and gives them structure, allowing them to stand upright. Fiber is not found in animal foods like meat and dairy. Humans cannot digest fiber, so fiber makes its way through the digestive tract to the colon.

Bacteria in the colon ferment fiber for energy. Different types of bacteria prefer different types of fiber for fuel. Incorporating a large assortment of plant foods into your diet is a great way to make sure you get the various types of fiber that all your microbes are looking for.

But we can’t give fiber all the credit. Plants also have beneficial compounds called polyphenols, another substance found only in plants. Polyphenols serve to protect plants in several ways. Many polyphenols are antioxidants and protect human cells from damage when we consume them. There are several categories of polyphenols, each with benefits to human health.

Polyphenols have an interesting relationship with the gut microbiota. They help nourish the microbes. In turn, the microbes turn the difficult to digest polyphenols into forms that are more easily absorbed in the intestine. Many of the health benefits of polyphenols can only be gained if they are processed by gut bacteria4.

30 Plant Based Foods A Week

Thirty different plant foods per week might sound like a lot, but you might be surprised at how quickly they can add up. It might take a little more planning and perhaps more frequent trips to the grocery store but getting to 30 plants is an achievable goal for most people.

Food Diversity

Tips for Increasing Daily Plant Food Diversity

Breakfast

Add veggies to your scrambled eggs or omelet.

  • Almost any cooked vegetable will work such as bell peppers, hot peppers, tomatoes, onions, mushrooms, broccoli, and spinach.
  • Fermented vegetables such as kimchi are also great with eggs.

Buy bags of mixed frozen fruit.

  • Easily add a variety of fruits to your yogurt, smoothies, or hot cereal.

Get generous with nuts and seeds.

  • Add a combination of nuts and seeds to cold cereal, hot cereal, yogurt, or smoothies.
  • Great options include freshly ground flax seed, chia seeds, walnuts, almonds, pecans, and hazelnuts.

Top your whole grain toast with plants!

  • Mashed avocado and tomato slices are perfect companions on toast.
  • Consider other toppings like alfalfa sprouts, microgreens, or sesame seeds.

Throw some greens in your smoothies.

  • Add a handful of fresh or frozen spinach.
  • Tougher greens like kale might be less appealing for a smoothie, but if you simply put your greens through a food processor it makes for a much smoother consistency.
  • You can freeze your processed greens in a baggie and grab handfuls as needed. Or consider putting the processed greens in ice cube trays with a little water or even juice.

Make your own granola.

  • Use old fashioned oats with different combinations of unsweetened dried fruits, coconut, nuts, and seeds. You can keep the sugar content much lower than with store bought granola while increasing plant food diversity.

Check out this post for some healthy Low FODMAP Breakfast Ideas.

Lunch and Dinner

Use whole grain bread for your sandwich and pile it high with vegetables.

  • Veggies great for cold sandwiches include greens, tomatoes, cucumbers, bell peppers, hot peppers, avocado, onions, and sprouts.
  • Grilled vegetables such as eggplant, zucchini, bell peppers and mushrooms make for a great hot sandwich.

Combine cooked lentils with processed vegetables and use in place of, or mixed with, ground beef.

  • Throw carrots and celery in the food processor to get a fine shred. Sauté. Then mix with cooked lentils. Combine this mixture with ground beef to add nutrients and save money when you make dishes like spaghetti and tacos. You can freeze the meat and lentil mixture for up to three months.

Sprinkle seeds on everything.

  • Top your salad with pumpkin seeds, sunflower seeds, sesame seeds, and poppy seeds.
  • Sprinkle seeds on stir fry, casseroles, soup, and eggs.

Buy mixed vegetables for your sides.

  • Frozen mixed vegetables are an easy and inexpensive side dish.
  • Fresh mixed vegetables are also available precut and ready to sauté.
  • For the healthiest options avoid prepared vegetables with added seasonings and sauces.
  • Feel free to add your own herbs and spices to boost the polyphenol content.

Get creative with greens.

  • Add cooked greens like spinach, swiss chard, collard greens, or kale to casseroles, homemade macaroni and cheese, and other pasta dishes like spaghetti or lasagna.

Snacks

Buy or make crackers with whole grains and seeds.

Go for my personal favorite, chips and salsa.

  • Use chips with whole grains and seeds and fresh pico de gallo.
  • Whip up some fresh guacamole for another nutrient loaded dip option.

Or choose the classic healthy snack – vegetables and dip.

  • Prepare a variety of fresh vegetables ahead of time.
  • Make a yogurt-based dip with fresh herbs like dill, basil, parsley, mint, chives, or cilantro.

Snack on unsalted or lightly salted mixed nuts.

  • Raw or dry roasted are good options.
  • Pair nuts with some fresh fruit for a well-rounded snack.

Make a simple fruit salad.

  • Dice whatever fresh fruit is in season, combine in a large bowl. Add a squeeze of lemon, lime, or orange juice to prevent browning.
How to Eat 30+ Plant Foods Per Week

10 Plant Packed Recipes to Try

Here are a handful of my favorite recipes, each with five or more different plant-based foods.

  1. Sweet Potato Breakfast Hash
  2. Winter Fruit Salad
  3. Ratatouille with Spicy Italian Chicken Sausage and Creamy Polenta
  4. Mediterranean Bowl with Salmon
  5. Roasted Vegetable Grain Bowl with Tzatziki Sauce
  6. Cozy Autumn Wild Rice Soup
  7. Asian Slaw with Ginger Peanut Dressing
  8. Mexican Stuffed Sweet Potatoes
  9. Stuffed Acorn Squash
  10. Greek Salad

Should I go Vegetarian or Vegan?

Going vegetarian or vegan is a personal choice. A plant-based diet comes with many health benefits, but plant-based does not necessarily mean vegetarian or vegan. Simply adding a larger variety of plant foods to your diet can make a difference – aim for 30 a week.

In fact, in the American Gut Project, a vegetarian or vegan diet was not found to be better than one containing animal products. Instead, it was the variety of plant foods that was important. If you eat large portions of animal protein every day, cutting back on your portion sizes and filling up on more fruits, vegetables, whole grains, nuts, seeds, and legumes is a good place to start.

Importance of Food Diversity – Beyond the Gut

A plant rich diet is one that is high in fiber, vitamin and minerals, and polyphenols.  The nutrients in plant foods have been associated with many health benefits beyond the gut. And, as mentioned above, fiber and polyphenols are found only in plant sources. So read on to explore the importance of food diversity in other areas of health.

Importance of Food Diversity - Beyond the Gut

Heart Health

High fiber diets can improve heart health by lowering cholesterol. And remember those SCFA that are a byproduct of bacterial fermentation? They can help heart health by reducing inflammation and blood pressure. The polyphenols in plant foods also protect against heart disease.

Diabetes

Those with diabetes and pre-diabetes can benefit from the soluble fiber in plant foods. Soluble fiber is associated with better blood sugar control and improved insulin sensitivity5. This means your body needs less insulin to bring blood sugar back to normal after eating. Fiber is also associated with decreased risk for developing type 2 diabetes.

Cancer Prevention

A high fiber diet may be associated with a reduced risk of cancer. The evidence seems to be the most compelling in reducing the risk of colon cancer6. This may be because fiber helps rid the body of carcinogens when you poop.

The reduction in colon cancer risk is also partly the handiwork of those helpful SCFAs again. There is also some evidence for protection from breast cancer.

Although more research is needed, polyphenols also seem to have some anticancer effects7. Certain types of polyphenols may be more protective than others. So once again, including a wide variety of plant foods might be they best way to make sure you get all the protection plant foods have to offer.

Immunity

Most of our immune system lies within the gut. A healthy microbiome boosts immunity by strengthening the gut barrier, stimulating production of intestinal mucus, and affecting the production of immune cells4.

The fiber and polyphenols in plant foods helps the microbiota thrive. Polyphenols also have anti-inflammatory and antimicrobial properties. Incorporating foods high in polyphenols in your diet may help protect against infectious diseases8.

Weight Management

Weight management is a complicated subject, but many experts feel that a high fiber diet can help with weight maintenance by increasing feelings of fullness after a meal and reducing overall calorie intake.

Recent research also suggests that an individual’s microbiome may play a large role in weight maintenance, with certain groups of bugs being associated with obesity vs thinness. And as you now know, plant foods and fiber provide fuel for these bugs.

Conclusion

The importance of food diversity, especially plant diversity, is becoming clear in its impact on human health. People who consume 30 different plant foods per week tend to have greater diversity of bacteria in their guts. Most experts agree that this diversity of microbes is associated with better health.

While a vegetarian or vegan diet can be healthy, so can a diet that includes moderate portions of meat and dairy. Avoiding animal products might not be as important to gut health as including a large variety of plant foods.

Use some of the ideas presented above to get out of your daily food routine and improve the diversity in your diet. Your gut, health, and waistline will thank you!

References

1.         Marchesi JR, Ravel J. The vocabulary of microbiome research: a proposal. Microbiome. 2015;3(1):1-3. doi:10.1186/s40168-015-0094-5

2.         McDonald D, Hyde E, Debelius JW, et al. American gut: an open platform for citizen-science microbiome research. bioRxiv. 2018;3(3):1-28. doi:10.1101/277970

3.         Chambers ES, Preston T, Frost G, Morrison DJ. Role of Gut Microbiota-Generated Short-Chain Fatty Acids in Metabolic and Cardiovascular Health. Curr Nutr Rep. 2018;7(4):198-206. doi:10.1007/s13668-018-0248-8

4.         Laparra JM, Sanz Y. Interactions of gut microbiota with functional food components and nutraceuticals. Pharmacol Res. 2010;61(3):219-225. doi:10.1016/j.phrs.2009.11.001

5.         Chen C, Zeng Y, Xu J, et al. Therapeutic effects of soluble dietary fiber consumption on type 2 diabetes mellitus. Exp Ther Med. 2016;12(2):1232-1242. doi:10.3892/etm.2016.3377

6.         McRae MP. The Benefits of Dietary Fiber Intake on Reducing the Risk of Cancer: An Umbrella Review of Meta-analyses. J Chiropr Med. 2018;17(2):90-96. doi:10.1016/j.jcm.2017.12.001

7.         Zhou Y, Zheng J, Li Y, et al. Natural polyphenols for prevention and treatment of cancer. Nutrients. 2016;8(8). doi:10.3390/nu8080515

8.         Marín L, Miguélez EM, Villar CJ, Lombó F. Bioavailability of dietary polyphenols and gut microbiota metabolism: Antimicrobial properties. Biomed Res Int. 2015;2015. doi:10.1155/2015/905215

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