Fiber and Fertility: What You Need to Know

An upset stomach and constipation are a common pregnancy complaint. The “fix” most doctors will recommend is to increase fiber intake. And they’re not wrong. Focusing on fiber can help ease some of the discomfort during pregnancy. What’s even more interesting, though, is that fiber can also help before and after pregnancy. Believe it or not, fiber is an influential factor in fertility. 

Does Fiber Enhance or Interfere With Fertility?

Yes, there are some mixed messages with regards to fiber and fertility. One study published in 2009 in the American Journal of Clinical Nutrition concluded that a high-fiber diet was “significantly associated with decreased hormone concentrations and a higher probability of anovulation.” In other words, more fiber meant less chance of ovulating.

However, the study was small (only 250 women) and only followed the participants for two consecutive menstrual cycles. Plus, fewer than one in 10 women in the study were getting the recommended amount of fiber per day. That means, the number of women eating at least 22 grams of fiber and not ovulating for one or both of those two cycles was extremely low. One person could drastically tip the percentages up or down. If you were to base your habits on this one small study, you’d probably stick to a low-fiber, high-fat diet.  

But a larger body of evidence points in a much different direction, proving that fiber can enhance fertility. Here’s how:

• Fiber helps maintain a healthy weight – Being overweight or obese has long been known to impact reproductive health. Obesity tends to alter hormone levels, which may make it harder to get pregnant. Obesity can also hinder ovulation. Those who eat more fiber, however, are less likely to be overweight or obese. Fiber-rich diets make you feel fuller longer, which often prevents overeating. Fiber is also helpful in stabilizing blood sugar, but more on that below.
• Fiber reduces risk of insulin resistance – Insulin resistance can trigger the ovaries to overproduce androgen hormones. In women with polycystic ovary syndrome (PCOS), this is of particular concern, as excess androgens can lead to irregular ovulation or anovulation (no egg releases). By increasing fiber intake, you can improve your body’s insulin sensitivity. This not only reduces your risk of infertility struggles, but also decreases your chances of developing metabolic disorders like type 2 diabetes. High-fiber diets, where women consume more than 25 grams per day and men consume more than 38 grams, reduce the risk of type 2 diabetes by as much as 20-30%. 
• Fiber fuels the gut microbiome – The gut microbiome is a principal regulator of circulating estrogens. More specifically, the gut microbiota convert bound estrogens into their free and active forms. This process can be impaired by a lower diversity of microbes circulating in the gut. To maintain those good microbes, you need to feed them. Fiber is their primary source of fuel, which is why it’s important to follow a high-fiber diet when trying to conceive. This is also an important component during pregnancy, as growing research suggests the mother’s microbiome is passed on to baby in utero. Develop a healthy gut early, and it will help your baby’s microbiome flourish! 

Fiber Intake: Striking the Right Balance

Now that you understand how fiber affects fertility, it’s time to chow down! Obviously, you don’t want to eat too much too soon. And you want to be sure you’re eating the right kinds of fiber.

First of all, the recommended dietary intake for fiber is 25-28 grams per day for women and 31-34 grams per day for men. The specific targets vary by age, but you can find those details in the Dietary Guidelines for Americans, 2020-2025. Unfortunately 90% of women and 97% of men don’t meet those recommended intakes. If you’re one of them, those numbers may be overwhelming. So what can you do?

Break it up. Aim for 10-15 grams of fiber per meal. The goal will feel much more manageable when you break it up into smaller increments. Plus, spreading your fiber intake throughout the day is better for digestion and nutrient absorption. You’ll reach those daily targets without upsetting your stomach. It’s a win-win!

The Best Sources of Fiber for Women

More important than the exact grams, though, is the diversity of your fiber. Women trying to conceive should focus on the diversity of plants you consume. According to the American Gut Project, the goal is to eat more than 30 different kinds of plants each week. This increases the range of bacteria in the gut, leading to a healthy microbiome.

Don’t worry; eating 30 kinds of fiber is easier than it sounds. Fiber is found in fruits, vegetables, nuts, seeds and legumes. Mix up your meals with any variety of these plant foods, and you’ll be on the right “tract.” Some easy ways to get variety include:

• Add chia seeds to your smoothies
• Make vegetable-based soups by blending sautéed veggies and adding some broth or water
• Make a mix of whole nuts and seeds to snack on between meals

For women who are already pregnant, constipation may be a real issue. Your doctor probably already told you to increase your fiber intake. But make sure it’s a mix of soluble and insoluble fibers.

Insoluble fiber does not dissolve in water. Instead, it attracts water, thereby softening stool and making it easier to have a bowel movement. Good sources of insoluble fiber include:

• Wheat bran
• Nuts
• Cauliflower
• Chia seeds
• Flax seeds

Soluble fiber, on the other hand, dissolves in water. It creates a gel-like consistency that helps block the absorption of fats and cholesterol, particularly the “bad” cholesterol (LDL). Good sources of soluble fiber include:

• Oats
• Beans
• Apples
• Carrots
• Peas

Food aversions during pregnancy may make it difficult to eat a lot of fiber-rich plant sources. In these cases, the best alternatives are fiber powders. Try one of these:

Acacia

Acacia is a soluble fiber that mixes easily with liquids. Add it to a glass of water or your morning cup of coffee. It’s usually well-tolerated and can be used on a daily basis. 

Psyllium husk

This is a thicker fiber powder, so you won’t have much success stirring it into liquids. You can, however, blend psyllium husk powder into a smoothie or use it to bulk up baked goods.  

Small Changes for Big Rewards

Fiber has long been touted for its role in regularity. Unfortunately, the link between fiber and fertility is not as commonly discussed. But that doesn’t mean the connections aren’t there. In addition to supporting healthy weight maintenance and blood sugar levels, fiber helps balance sex hormones and creates a thriving microbiome that you’d be proud to pass on to your baby. Overlooking these benefits could significantly sway your chances of getting pregnant, staying pregnant and having a healthy child. Keep in mind, these are big rewards that don’t take much effort at all. Simply adding fiber-rich foods to your diet is enough to make a difference. Of course, fiber is not the panacea to your pregnancy journey. But these small dietary changes can certainly get you one step closer to creating the family you always wanted.