Phytoestrogens: to eat soy or to not eat soy?


Yes, this meal is safe to eat. Photo courtesy of United Soybean Board.

Are phytoestrogens like soy safe to eat?

This is a common question in my office. People tell me they have heard soy has strong estrogen-like effects that will worsen PMS or PCOS. They have heard that soy is bad for the thyroid. Soy might even disrupt men’s hormones and cause them to grow breasts. These stories are circulated in the media, particularly online and social media, often enough that I appreciate why people ask the question: are phytoestrogens like soy safe?

The TLDR answer is: yes, soy and other phytoestrogens are safe for women and men to eat.  In many cases, they may even be protective for women experiencing problems related to high or low estrogen levels.

What are phytoestrogens?

Phytoestrogens are plant compounds that have estrogen-like properties. This is because their shapes loosely resemble the shape of a naturally occurring estrogen molecule, estradiol. But whereas estradiol fits in an estrogen receptor perfectly, like a key in a lock, phytoestrogens do not. Phytoestrogens are more like a toy key that you give a toddler to play with. Phytoestrogens gently nudge estrogen receptors, simultaneously creating a small amount of estrogenic activity and blocking the receptor from receiving stronger stimulation from other sources.

And this is where the therapeutic effect of phytoestrogens comes from: in situations where estrogen levels are already too high, phytoestrogens protect estrogen receptors from overstimulation. And in situations where estrogen levels are uncomfortably low, like menopause, the gentle nudge against an estrogen receptor may provide just enough activity to relieve discomfort.

In other words, phytoestrogens modulate estrogen levels. When natural estrogen levels are high phytoestrogens have a net anti-estrogen effect, and when natural estrogen levels are low their effect becomes more estrogenic.

Where do phytoestrogens come from?

There are 2 main types of phytoestrogen: isoflavones and lignans.

  • Isoflavones: a plant molecule found in the plant family Fabacea (bean family), especially soybeans.
    • Highest concentrations in: edamame or whole soy beans, tempeh, tofu, miso, soy butter
    • Other sources: chickpeas, peanuts
  • Lignans: a component of insoluble fiber, found in many plants.
    • High concentrations in: flax seeds, sesame seeds, cereal brans (e.g. oat bran, rice bran)
    • Other sources: whole grains (wheat, millet, rye, barley), legumes, nuts, asparagus, grapes, kiwi, lemons, oranges & pineapple

Dietary lignans depend on healthy gut flora to metabolize or change them into a form where they are biologically active. And it is not just the estrogen receptor activity that makes lignans healthy, they also have beneficial effects on the cardiovascular system.

Phytoestrogens and Digestive Health:

If phytoestrogens were a cure-all for estrogen related problems, it wouldn’t be a secret. But they do have a measurable and meaningful impact on many hormonal imbalances. For example:

A 2015 meta-analysis of 15 studies done on phytoestrogens and menopausal symptoms shows that they are able to reduce frequency of hot flashes compared to placebo.

A 2012 quasi-randomized study of 146 women with PCOS in Italy showed that use of a phytoestrogen lignan isolate for 3 months reduced levels of DHEA-S and testosterone and improved lipid profiles by reducing triglycerides and LDL (aka “bad cholesterol”) levels.

Clinically, I suspect that one of the keys to how people respond to phytoestrogens is contingent on the state of their digestive health. It is known that lignans, for example, need to undergo transformation by healthy gut bacteria to become fully active as phytoestrogens in the body. And the balance between healthy and unhealthy gut bacteria is also likely the lynch pin for whether people find foods containing phytoestrogens beneficial for their hormonal and metabolic balance, or a cause of gas, bloating and fatigue.

Not everyone responds well to soy and other foods rich in phytoestrogens. Digestive problems are common among people who do not tolerate soy and other legumes well.  One reason for this is the fructo-oligo-saccharide content of legumes, recall that the legume family is the plant family most well known for producing phytoestrogens, are fodder for the fermenting bacteria responsible that cause the digestive condition SIBO (small intestine bowel overgrowth).

This underscores why digestive health is such a critical piece of the puzzle in finding hormonal balance for many women. Fortunately, there are tests available to evaluate digestive health, including tests for SIBO to see if there is a bacterial overgrowth that requires treatment before phytoestrogens can be successfully tolerated and metabolized, as well as tests to determine the presence, abundance and diversity of healthy gut bacteria.

About the author:

Miranda Marti, ND, LAc is a body positive naturopathic physician and acupuncturist specializing in the holistic treatment of PCOS and other chronic conditions affecting hormonal, digestive and mental health.

Why Am I So Tired: Nutrition

From simple lifestyle habits to complex medical problems, why we feel tired can have many causes. In this series, I’m tackling some of the lifestyle factors associated with fatigue that lend themselves to home troubleshooting. This week’s topic is:


What we eat is important. But even a diet made up of the best quality foods can leave us feeling tired if the timing and quantities of those foods is off.  This is because with rare exception, every cell in our body relies on glucose as it’s fuel to create energy. If our fuel supply is inadequate or disrupted throughout the day, that can leave use feeling tired.

Physical fatigue can feel like lethargy, muscle weakness, loss of stamina, the need to lay down and rest, or feeling drained by the day’s activities. Mental fatigue can be experienced as brain fog, irritability or mood swings, confusion, and feeling scattered, unmotivated or unfocused.

How much do I need to eat to avoid fatigue?

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Banana Berry Protein Smoothie by Amazing Almonds

There are a few nutritional guidelines that are worth trouble-shooting for anyone who feels tired.

  1. Am I eating an appropriate amount of protein throughout the day?
  2. Am I eating at least 150 grams of carbohydrate throughout the day?
  3. Do I eat frequently enough throughout the day?

It may require a little legwork to answer these questions, particularly reading the nutrition labels of prepared foods and looking up nutritional information for whole or fresh foods. But the answers are a worthwhile and necessary for ruling out simple nutritional oversights as a cause for fatigue.

Visit my Pinterest boards for snack and meal recipes that provide an energizing balance of protein and carbohydrates.

Protein Needs:

Generally speaking a healthy person’s protein need is based on their age, sex, body size and activity level.  Use this protein calculator to determine your protein needs per the American Dietetic Association (ADA) and Centers for Disease Control and Prevention (CDC) recommendations.  Once you have the appropriate protein range that you should be consuming, keep a diet diary for a few days to tally up how much protein you are eating throughout the day to find out if you are achieving your goal.

A person with health problems may require more or less protein than the  average healthy person, so consult your doctor or a nutritionist about individual health-related protein needs.

Carbohydrate Needs:

Unless you are specifically following a ketogenic diet, which forces the body’s cellular metabolism to use ketones rather than glucose as fuel by following an extremely low carb diet, your body may feel tired or overwhelmed when your carbohydrate intake drops below 150 grams per day.  

Even though we are constantly told Americans eat too many carbohydrates, it can be surprisingly easy to eat too few. It has been my experience that in an effort to be healthy,  many health-conscious people actually overshoot the low-carb mark.  I see this particularly often when patients are reporting overwhelmed by brain fog, irritability and mood swings.

Flckr Creative Commons licensed for commercial use

Photo courtesy of I_Nneska

Here is an example of a diet diary of someone who is unintentionally eating less that 150 gm carbohydrate per day:

  • 8 AM breakfast: an apple (25-30 gms), scrambled eggs, coffee with half & half
  • 10 AM snack: a handful of almonds (6 gms) and a tall soy latte (18 gms)
  • noon lunch: Trader Joe’s Harvest with Grilled Chicken (20 gms) and sparkling water
  • 4 PM snack: LemonZest Luna Bar (26 gms)
  • 7 PM dinner: chicken breast, 1/2 cup quinoa (20 gms), 1 cup steamed broccoli (6 gms)

While this example diet supplies an adequate amount of protein, it only delivers 126 grams of carbohydrate which is low enough to leave someone feeling tired, irritable or overwhelmed.

How often do I have to eat to avoid fatigue?

Even the best quality foods in the world have a limited time to provide us with energy. This is because our digestive system is in constant motion. For most people, food is on its way to becoming a bowel movement about 4 hours after it is eaten.

While some people thrive going longer times between meals, it is not a strategy that works for everyone. If you are routinely going more than 4 hours between snacks or meals, try experimenting over several days with increasing your snack and meal frequency to see how your energy improves.

Diet diaries help

To fully trouble-shoot these dietary causes of mental and physical fatigue, I recommend keeping a food diary. This involves taking a day or two to record the amount of proteins and carbohydrates you are eating throughout the day, as well as when you are eating them, to see if you are meeting your goals to keep your body fueled.

For prepared foods, you can simply look at the nutrition label for their protein and carbohydrate content.

For fresh or whole foods, like fruits and vegetables, grains or meats that you cook for yourself, you can look up the nutritional content using the USDA nutrient database. Some people also prefer to use food-tracking apps on their smartphone, such as LoseIt.

Want to know more?

This is the second of a series of blog posts providing the Whole Life Medicine community with reliable information about important health topics. Check back with use for future posts or follow our Facebook page.

About the author: Evaluating causes of fatigue affecting physical and mental health is a specialty of Miranda Marti, ND. For information about scheduling a free 15 minute consult or making an appointment, please contact us or call our front desk at 425-398-9355.

Why Am I So Tired: Hydration

From simple lifestyle habits to complex medical problems, why we feel tired can have many causes. In this series I’m tackling some of the lifestyle factors associated with fatigue that lend themselves to home-trouble shooting. This week’s topic is:


We know water is vital to life.

A small decrease in our hydration can lead to an outsized drop in our energy levels, including physical energy that leaves us feeling lethargic and tired, and mental energy that leaves us feeling scattered, unmotivated and unfocused.

But how much water do I need to drink?

And what if I don’t like to drink it?

How much water do I need to avoid feeling tired?

The short answer is: it’s hard to say. Seriously, there isn’t a precise scientific consensus on how much water a person needs to drink, as is discussed in an informative 2010 article in the journal of Nutrition Reviews: Water, Hydration and Health.

Generally speaking, though, here are hydration guidelines for adolescent and adult men and women:

  • Women: 80 – 90 ounces of water per day from fluid and food sources
  • Men: 110 – 120 ounces of water per day from fluid and food sources

You might noticed that drinking water isn’t the only source of hydration. If you are not a fan of plain water, please see the section below for alternative means of keeping yourself well hydrated!

Some practical recommendations of when to increase your hydration from water, caffeine-free and unsweetened beverages and fresh fruits and vegetables:

  • Hydrate when you are thirsty.
  • Hydrate when you are feeling mentally tired.  Signs of mental fatigue: brain fog, indecisiveness and low motivation
  • Hydrate if your urine is darker than pale yellow. If your pee is darker than the color of straw, that’s a sign of dehydration.
  • Hydrate when you’ve been sweating, particularly if it has been for 45 minutes or longer.

And remember: too much of anything, even plain water, can cause serious health problems. The risks for overhydration are greatest when people consume more than 30 ounces of water per hour, exceeding the rate that the kidneys can adequately filter excess water into urine. If you want to read more, here is an interesting and well-researched article on the dangers of overhydration.

What if I don’t like drinking plain water?

Hydration doesn’t come from drinking plain water alone. Plenty of foods, especially fresh fruits and vegetables, contain enough water to be great sources of hydration. Hydrating through food is bladder-healthy because it slows the rate of water absorption, minimizing the chance you’ll experience the urge to pee shortly after drinking. And hydrating through food is muscle-healthy because it combines the water with electrolytes, natural sugars and vitamins that help muscles recover after activity and workouts.

  • Foods that are 90-99% water
    • strawberries, watermelon, cantaloupe, lettuce, spinach, cucumber, zucchini, tomato, celery, cauliflower, radish, cabbage, pickles, peppers, squash (cooked)
  • Foods that are 80-89% water
    • apples, pears, apricots, blueberries, plums, grapes, oranges, pineapple, carrots, peas, broccoli, yogurt
  • Foods that are 70-79% water
    • bananas, avocados, baked potatoes & sweet potatoes, cooked corn, cottage cheese, ricotta cheese

Other hydrating alternatives to plain water:

use via Flickr Creative Commons commercial license

Pitcher by Simon Pearce

  • caffeine-free herbal teas
  • decaffeinated black and green teas
  • infused water with mint, cucumber, lemons, limes, berries or other cut fruit
  • mineral waters and seltzers such as Talking Rain, La Croix and Spindrift

Want to know more?

This is the first in a series of blog posts proving the Whole Life Medicine community with reliable information about important health topics. Check back with us for future posts or follow our Facebook page.

About the author: Evaluating causes of fatigue affecting physical and mental health is a specialty of Miranda Marti, ND. For information about scheduling a free 15 minute consult or making an appointment, please contact us or call our front desk at 425-398-9355.