In Late Pregnancy Moderate the Intake of Powerful Anti-inflammatory Foods

The right side of the heart pumps deoxygenated blood from the body to the lungs, where it can fill up with oxygen, and then the left side of the heart pumps oxygen-rich blood from the lungs to the rest of the body. So, blood travels from the body to the right side of the heart to the lungs to the left side of the heart and back to the body.

But what happens in the womb? Fetuses’ lungs don’t work because they’re filled with fluid. How does the heart bypass the lungs and spread the oxygen-rich blood coming in through the umbilical cord to the rest of the body? Before we’re born, we have an extra blood vessel—the ductus arteriosus—that directly connects the right side of the heart with the left side of the heart, bypassing the fluid-filled lungs. When the baby is born and takes a first breath, this blood vessel closes. In about 1 in 10,000 births, though, the blood vessel closes prematurely before the baby is born, necessitating an emergency C-section, as I discuss in my video Caution: Anti-inflammatory Foods in the Third Trimester.

Most cases for which there’s a known cause are thought to be related to taking anti-inflammatory drugs such as aspirin or ibuprofen. This is because the way the body keeps this blood vessel open is with a class of inflammatory compounds called prostaglandins. If you take an anti-inflammatory drug, you can undermine your body’s ability to keep it open, and it could constrict closed prematurely. That’s why most authorities recommend that these nonsteroidal anti-inflammatory drugs (NSAIDs) be avoided in the third trimester. The likelihood that anything bad will happen is extremely remote, but it’s better to be safe than sorry.

Sometimes this premature constriction happens even when women are not taking drugs, so-called “idiopathic” cases, which is doctorspeak for “we have no idea what causes it.” If anti-inflammatory drugs can cause it, though, what about anti-inflammatory foods? A few years ago, in my video Chamomile Tea May Not Be Safe During Pregnancy, I profiled two incidents apparently caused by pregnant women drinking chamomile tea. One of which reversed in that the ductus opened right back up once the tea was stopped, but, in the other case, the other baby had to come right out. Since then, there have been other case reports of this occurring––for example, when a woman had been drinking a few ounces of an acai berry drink every day and when another woman had been drinking prune juice and a violet vegetable juice containing a blend of fruits and veggies. Pregnant women should, therefore, take special care when consuming lots of these powerful anti-inflammatory berry nutrients.

What about berries themselves, green tea, and all the other wonderful anti-inflammatory foods and beverages out there? A group of researchers in Brazil compared ultrasounds of the hearts of third-trimester babies whose moms ate a lot of these anti-inflammatory foods with those whose moms ate less, and they could tell a difference. The speed of blood through the ductus in the moms consuming the anti-inflammatory diet was higher, suggesting it was narrower, just like when you pinch the opening of a hose closed and can make water shoot out faster. Also, the right sides of the hearts of the babies whose moms were consuming the anti-inflammatory diet were larger than their left sides, suggesting some blood backup, again an indicator of a tighter ductus. The researchers suggested changes in late pregnancy diets may be warranted, but critics replied that the differences they noted might not have any clinical relevance, meaning it may not matter if the vessel is a little more open or closed. We don’t want to alarm women because many of these anti-inflammatory foods may be beneficial––such as cranberries, for example, which may be useful in preventing urinary tract infections, which can be a risk factor for premature birth. Consuming cranberries is attractive from a public health and cost standpoint if it can prevent some premature births.

Before cutting down on a healthy food such as cranberries, we’d want some stronger evidence that they’re potentially harmful. What about confounding factors? For example, women who ate lots of anti-inflammatory foods might have had other characteristics that could affect fetal blood flow. What we needed was an interventional trial in which pregnant women change their diets and see what happens, but we didn’t have such studies… until now.

A study has shown that cutting back on anti-inflammatory foods such as tea, coffee, dark chocolate, grapes, and citrus for a few weeks during the third trimester did indeed seem to open up the ductus during normal pregnancies. In women whose fetuses had abnormally constricted vessels, a few weeks of eliminating polyphenol-rich foods reversed the ductal constriction in 96% of cases. Importantly, researchers didn’t follow these babies after birth to see if it made any difference. That complete closure only happens in 1 in 10,000 births; we’re not sure what effects relative levels of constriction may have, so it’s too early to be instituting a ban on dark chocolate for pregnant women.

At this stage, what we’re left with is a note of caution. During the rest of your life, I recommend eating healthy foods such as berries and cocoa powder, but from about 28 weeks until birth, pregnant women may want to cut back until we know more.


In Chamomile Tea May Not Be Safe During Pregnancy, I profile those two case reports I mentioned above. As I noted in Anti-inflammatory Antioxidants, highly antioxidant foods are, in general, highly anti-inflammatory foods.

For comparisons between the strength of anti-inflammatory foods and drugs, see Watermelon for Sore Muscle Relief, Anti-inflammatory Life Is a Bowl of Cherries, and Which Spices Fight Inflammation?

The videos provide more information about healthy (and unhealthy) diets in pregnancy:

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

How Much Water Should We Drink Every Day?

More than 2000 years ago Hippocrates (460–377 BCE) said, “If we could give every individual the right amount of nourishment and exercise, not too little and not too much, we would have found the safest way to health.” What does that mean when it comes to water? Water has been described as a neglected, unappreciated, and under-researched subject, and further complicating the issue, a lot of the papers extolling the need for proper hydration are funded by the bottled water industry.

It turns out the often quoted “drink at least eight glasses of water a day” dictum has little underpinning scientific evidence . Where did that idea come from? The recommendation was traced to a 1921 paper, in which the author measured his own pee and sweat and determined we lose about 3% of our body weight in water a day, or about 8 cups (see How Many Glasses of Water Should We Drink in a Day?). Consequently, for the longest time, water requirement guidelines for humanity were based on just one person.

There is evidence that not drinking enough may be associated with falls and fractures, heat stroke, heart disease, lung disorders, kidney disease, kidney stones, bladder and colon cancer, urinary tract infections, constipation, dry mouth, cavities, decreased immune function and cataract formation. The problem with many of these studies is that low water intake is associated with several unhealthy behaviors, such as low fruit and vegetable intake, more fast-food, less shopping at farmers markets. And who drinks lots of water? People who exercise a lot. No wonder they tend to have lower disease rates!

Only large and expensive randomized trials could settle these questions definitively. Given that water cannot be patented, such trials seem unlikely; who’s going to pay for them? We’re left with studies that find an association between disease and low water intake. But are people sick because they drink less, or are they drinking less because they’re sick? There have been a few large prospective studies in which fluid intake is measured before disease develops. For example, a Harvard study of 48,000 men found that the risk of bladder cancer decreased by 7% for every extra daily cup of fluid we drink. Therefore, a high intake of water—like 8 cups a day—may reduce the risk of bladder cancer by about 50%, potentially saving thousands of lives.

The accompanying editorial commented that strategies to prevent the most prevalent cancers in the West are remarkably straightforward in principle. To prevent lung cancer, quit smoking; to prevent breast cancer, maintain your ideal body weight and exercise; and to prevent skin cancer, stay out of the sun. Now comes this seemingly simple way to reduce the risk of bladder cancer: drink more fluids.

Probably the best evidence we have for a cut off of water intake comes from the Adventist Health Study, in which 20,000 men and women were studied. About one-half were vegetarian, so they were also getting extra water by eating more fruits and vegetables. Those drinking 5 or more glasses of water a day had about half the risk of dying from heart disease compared to those who drank 2 or fewer glasses a day. Like the Harvard study, this protection was found after controlling for other factors such as diet and exercise. These data suggest that it was the water itself that was decreasing risk, perhaps by lowering blood viscosity (blood thickness).

Based on all the best evidence to date, authorities from Europe, the U.S. Institute of Medicine, and the World Health Organization recommend between 2.0 and 2.7 liters (8 to 11 cups) of water a day for women, and 2.5 to 3.7 liters (10 to 15 cups) a day for men. This includes water from all sources, not just beverages. We get about a liter from food and the water our body makes. So this translates into a recommendation for women to drink 4 to 7 cups of water a day and men 6 to 11 cups, assuming only moderate physical activity at moderate ambient temperatures.

We can also get water from all the other drinks we consume, including caffeinated drinks, with the exception of stronger alcoholic drinks like wines and spirits. Beer can leave you with more water than you started with, but wine actively dehydrates you. However, in the cancer and heart disease studies I mentioned above, the benefits were only found with increased water consumption, not other beverages.  

I’ve previously touched on the cognitive benefits of proper hydration here: Does a Drink Of Water Make Children Smarter?

Surprised tea is hydrating? See my video Is Caffeinated Tea Dehydrating?

Surprised that the 8-a-day rested on such flimsy evidence? Unfortunately, so much of what we do in medicine has shaky underpinnings. That’s the impetus behind the idea of evidence-based medicine (what a concept!). Ironically, this new movement may itself undermine some of the most effective treatments. See Evidence-Based Medicine or Evidence-Biased?

How else can we reduce our risk of bladder cancer? See Raw Broccoli and Bladder Cancer Survival.

What kind of water? I recommend tap water, which tends to be preferable from a chemical and microbial contamination standpoint. What about buying one of those fancy alkalizing machines? See Alkaline Water: a Scam?

It’s so nice to have data on such a fundamental question. We have much to thank the Adventists for. You will see their studies cropping up frequently. See, for example, Plant-Based Diets and Diabetes, The Okinawa Diet: Living to 100, and Evidence-Based Eating.

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

The Best Diet for Rheumatoid Arthritis

Rheumatoid arthritis is a chronic systemic autoimmune disease affecting millions. It is characterized by persistent pain, stiffness, and progressive joint destruction leading to crippling deformities, particularly in the hands and feet. What can we do to prevent and treat it?

In my video Why Do Plant-Based Diets Help Rheumatoid Arthritis?, I show a famous 13-month randomized controlled trial of plant-based diets for rheumatoid arthritis where patients were put on a vegan diet for three and a half months and then switched to an egg-free lactovegetarian diet for the remainder of the study. Compared to the control group (who didn’t change their diet at all), the plant-based group experienced significant improvements starting within weeks. Their morning stiffness improved within the first month, cutting the number of hours they suffered from joint stiffness in half. Their pain level dropped from 5 out of 10 down to less than 3 out of 10. Disability levels dropped, and subjects reported feeling better; they had greater grip strength, fewer tender joints, less tenderness per joint, and less swelling. They also had a drop in inflammatory markers in their blood, such as sedimentation rate, C-reactive protein, and white blood cell count. As a bonus, they lost about 13 pounds and kept most of that weight off throughout the year.

What does diet have to do with joint disease?

Rheumatoid arthritis is an autoimmune disease, in which our own body attacks the lining of our joints. There’s also a different autoimmune disease called rheumatic fever, in which our body attacks our heart. Why would it do that? It appears to be a matter of friendly fire.

Rheumatic fever is caused by strep throat, which is itself caused by a bacterium that has a protein that looks an awful lot like a protein in our heart. When our immune system attacks the strep bacteria, it also attacks our heart valves, triggering an autoimmune attack by “molecular mimicry.” The protein on the strep bacteria is mimicking a protein in our heart; so, our body gets confused and attacks both. That’s why it’s critical to treat strep throat early to prevent our heart from getting caught in the crossfire.

Researchers figured that rheumatoid arthritis might be triggered by an infection as well. A clue to where to start looking was the fact that women seem to get it three times more frequently than men. What type of infection do women get more than men? Urinary tract infections (UTIs). So, researchers started testing the urine of rheumatoid arthritis sufferers and, lo and behold, found a bacterium called Proteus mirabilis. Not enough to cause symptoms of a UTI, but enough to trigger an immune response. And indeed, there’s a molecule in the bacterium that looks an awful lot like one of the molecules in our joints.

The theory is that anti-Proteus antibodies against the bacterial molecule may inadvertently damage our own joint tissues, leading eventually to joint destruction. Therefore, interventions to remove this bacterium from the bodies of patients, with consequent reduction of antibodies against the organism, should lead to a decrease in inflammation.

As we saw in my video Avoiding Chicken to Avoid Bladder Infections, urinary tract infections originate from the fecal flora. The bacteria crawl up from the rectum into the bladder. How might we change the bugs in our colons? By changing our diet.

Some of the first studies published more than 20 years ago to fundamentally shift people’s gut flora were done using raw vegan diets, figuring that’s about as fundamental a shift from the standard Western diet as possible. Indeed, within days researchers could significantly change subjects’ gut flora. When researchers put rheumatoid arthritis sufferers on that kind of diet, they experienced relief, and the greatest improvements were linked to greatest changes in gut flora. The diet was considered so intolerable, though, that half the patients couldn’t take it and dropped out, perhaps because they were trying to feed people things like “buckwheat-beetroot cutlets” buttered with a spread made out of almonds and fermented cucumber juice.

Thankfully, regular vegetarian and vegan diets work too, changing the intestinal flora and improving rheumatoid arthritis. However, we didn’t specifically have confirmation that plant-based diets brought down anti-Proteus antibodies until 2014. Subjects that responded to the plant-based diet showed a significant drop in anti-Proteus mirabilis antibodies compared to the control group. Maybe it just dropped immune responses across the board? No, antibody levels against other bugs remained the same; so, the assumption is that the plant-based diet reduced urinary or gut levels of the bacteria.

A shift from an omnivorous to a vegetarian diet has a profound influence on the composition of urine as well. For example, those eating plant-based had higher levels of lignans in their urine. Up until now, it was thought that they only protected people from getting cancer, but we now know lignans can also have antimicrobial properties. Perhaps, they help clear Proteus mirabilis from the system. Either way, these data suggest a new type of therapy for the management of rheumatoid arthritis: anti-Proteus measures including plant-based diets.


I have to admit I had never even heard of Proteus mirabilis. That’s why I love doing work—I learn as much as you do!

I explored another unconventional theory as to why plant-based diets are so successful in treating inflammatory arthritis in Potassium and Autoimmune Disease.

There’s another foodborne bacteria implicated in human disease, the EXPEC in chicken leading to urinary tract infections—another game-changer: Avoiding Chicken To Avoid Bladder Infections.

I have a bunch of videos on gut flora—the microbiome. They include: 

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Image Credit: Sally Plank / Flickr. This image has been modified.