Written by Melissa Duce MS, RDN, LD
There is no shortage of pills, powders, fortified foods, and beverages that claim to improve your gut health and solve your digestive issues. You may find yourself wondering which products, if any, will help you and your own unique needs. The answer may be more simple than you think and doesn't require expensive specialty products. The best way to improve gut health is to eat a greater variety of plants: fruits, vegetables, nuts, seeds, and grains.
You see, our digestive tract—specifically, the large intestine—is home to different types, or strains, of bacteria, which work behind the scenes to keep us healthy. As a whole, these bacteria are called the gut microbiome. A robust microbiome not only supports digestion and strengthens the walls of the large intestine, but also has a positive impact on many other systems and functions in your body, including the immune system, metabolism, insulin sensitivity, cardiovascular health, inflammation, and brain function. In other words, your microbiome is important for gut health and is vital in supporting your overall health.
Gut health is improved not only by increasing the number of good bacteria in the microbiome, but even more so by increasing the diversity of bacteria. There is not an exact number of bacteria that equates to optimal health, but we do know that the greater the bacterial diversity of the gut microbiome, the greater the overall health and benefit. Although many aspects of diet quality have an impact on our gut microbiome, our intake of plants—vegetables, fruits, grains, nuts, and seeds—has the greatest positive impact.
So, how does eating plants improve your microbiome? Plant foods are the best source of dietary fiber. Outside of taking fiber supplements, plants are the only source of fiber. I know, I know. Fiber doesn’t sound exciting. You may be ready to click away to find something more deserving of a headline. But please, stay for a minute and read on!
Our bodies are unable to fully digest fiber in the foods that we eat. The undigested fiber eventually enters the large intestine, where the resident healthy bacteria can feed on it, grow, multiply, and diversify. As the healthy bacteria grow and diversify, you reap the health benefits. So, let’s dive into the specific foods that give your microbiome a boost. But first, a note about special diets. If you are in the elimination phase of a low FODMAP diet, have allergies, or otherwise don’t tolerate some of these foods, you’re probably seeing red flags here. Not to worry! Although these foods have great health benefits, they are not great for your health if you can’t tolerate them. Increasing the variety of plant foods that you do tolerate will still support your gut microbiome.
Vegetables
You’ve heard it your whole life—”Eat your vegetables!” As annoying as it may be, your parents were right. Read any article or book about improving your health and reducing your risk of cancer or chronic disease, and you’re likely to hear this same advice. Vegetables are not only low calorie, high in vitamins and minerals, and contain disease-fighting phytonutrients, but they are also high in fiber. If I had to prioritize which vegetables to include, pulses would top my list. Pulses include beans, lentils, chickpeas, and peas...and the bacteria in your gut love feeding on them. Some of my favorite ways to increase the variety of vegetables at home include adding split red lentils to soups and other saucy foods, serving beans on taco night, and including both a cooked vegetable and a fresh, raw vegetable (like salad or carrots) at mealtime.
Fruits
I’m surprised by the number of people I’ve talked to over the years who avoid fruit because it has “too much sugar” or because they think fruit will sabotage their weight loss attempts. In reality, whole, fresh fruit (not fruit juice) is an important source of vitamins and minerals, fiber, and disease-fighting phytonutrients such as polyphenols. It is also low-calorie and filling. I can say with confidence that in my 15 years as a dietitian, I’ve never met someone whose health suffered due to eating too much fresh fruit. Fresh fruit will give your microbiome the fuel it needs to grow and diversify the good bacteria and reduce the levels of disease-causing bacteria. A bonus is that fruit is great at helping to regulate your bowel habits. Constipation? Try eating two kiwifruit per day. Diarrhea? Try adding a serving of applesauce or banana. Ultimately, the type of fruit you choose is less important than eating a variety and making sure to include fruit in your diet each day.
Grains
The type of fiber found in different grains varies, so once again, diversity is key! Examples of grains include well-known varieties such as wheat, barley, oats, and rice, as well as lesser-known grains like amaranth and millet. An easy way to increase grain diversity in your diet is to select multigrain bread, cereal, and crackers instead of their single-grain counterparts. Now, there is a caveat here. If you have Celiac disease, IBS, or other gut issues, you may need to exclude or limit certain grains from your diet. This does not, however, mean that you must miss out on the benefits of a grain-rich diet. For those with Celiac disease, try including different gluten-free grains, such as brown rice, millet, quinoa, buckwheat, and certified gluten-free oats. If you are in the elimination phase of a low FODMAP diet, you can include low FODMAP servings of spelt, buckwheat, rice, millet, and oats.
Nuts and Seeds
Nuts and seeds top the list of heart-healthy foods (for good reason!), but they are often overlooked when it comes to gut health. Nuts and seeds are rich sources of vitamins, minerals, fiber, protein, fat, and phytonutrients, and you can benefit from these nutrients without needing to consume large quantities. For comparison purposes, one ounce of almonds (20-24 almonds), contains about the same amount of fiber as a medium sweet potato. One ounce of chia seeds contains as much fiber as 5 medium carrots. Wow! Work toward including one ounce of nuts and seeds each day. Try topping salads or yogurt with nuts, mixing chia or flaxseeds into your overnight oats, or tossing some cashews or sesame seeds into a stir fry.
Probiotic and Fermented Foods
Though probiotics are not exclusive to plant foods, they are worth mentioning here. Probiotics are specific strains of bacteria and yeast that offer a proven (i.e. well-researched) health benefit when we eat them. When you eat a food that contains probiotics, these health-promoting bacteria can set up shop in your gut, and become a part of your gut microbiome. Probiotic foods, such as kefir and probiotic yogurts (i.e. Activia), have specific probiotics added in quantities that provide a health benefit. Fermented foods, such as regular yogurt, kombucha, kimchi, and sourdough bread, are fermented using different bacteria or yeast. Some fermented foods also contain live bacteria or yeast that can offer a health benefit, even though they are not considered probiotics. The fermentation process has the added benefit of making foods more easily digestible, and it improves their vitamin and antioxidant activity. If you are not already including probiotic and fermented foods in your diet, try adding some delicious kefir at breakfast, or top your dinner with kimchi.
Let’s set some goals!
If your baseline intake of plant foods is minimal, it’s ok (and recommended) to slowly work up to the goals listed below. A sudden significant increase in fiber can have some…uncomfortable effects. Try focusing on just one group at a time. If you are already meeting the recommended servings of each group, well done! It’s time to focus on diversifying the types of plant foods that you eat. The daily goal for each group is:
5 servings of vegetables. A sub-goal here is to include at least one serving of pulses (beans, lentils, chickpeas, peas) daily.
3 servings of fruit
5 servings of whole grains
1 oz of nuts/seeds
Include a serving of a probiotic or fermented food each day
Where do I start?
To start, think about a typical day of meals and snacks. Where are some opportunities to add fruits, vegetables, nuts/seeds, and grains? Can you include foods from each of these groups in each meal? If you tend to eat the same plant foods each day, how can you change it up? Remember that any change you make in your diet needs to be sustainable for you. If life is too busy to spend your evenings peeling and chopping fresh produce, don’t stress! Stock up on frozen steamable bags of veggies, salad kits, and canned beans or lentils. Making healthy choices should never feel like a burden!
When will I see results?
With any diet or lifestyle change, the best results come with consistency over time. In this case, though, there is good news. Improving the plant diversity of your diet can influence your gut microbiome in as little as 24 hours. In other words, eat more plant foods today, change your gut health tomorrow. Of course, this does not mean that all of your digestive woes can be solved overnight, especially when you have conditions that require continuous symptom management. The changes that happen are at a microscopic level, but even small improvements can move your health in the right direction. Remember that improving your gut microbiome doesn’t just influence your digestive health—improving your gut microbiome has a positive impact on your health in general. Your immune system, heart, and brain will thank you, as well!
Looking for more support?
The journey to better health can be overwhelming, especially when coupled with a new diagnosis, a new diet, or just the everyday stressors that life brings. Working with a Registered Dietitian (like me!) can help ease the stress of planning your meals and managing symptoms, and help you enjoy food again. To learn more, book a free discovery call and let's talk!