The Antioxidant Power of Açaí vs. Apples

There are so many açaí products on the market now, from frozen pulp in smoothie packs to freeze-dried powder and supplements. How is it eaten traditionally? “In the Brazilian Amazon, the Indian tribes of the forest cut down the tree and eat the palm heart…then urinate on the rest of the tree to attract a species of palm beetle to lay its eggs inside the tree. Several weeks later, they return to harvest 3–4 pounds of beetle grub larvae….” I think I’ll just stick to my smoothie pack.

“Despite being used for a long time as food and beverage” in the Amazon, açaí berries have only been researched scientifically since the beginning of this century. A number of years ago, I reviewed that research in my video Clinical Studies on Açaí Berries, starting with in vitro studies showing that açaí could kill leukemia cells in a petri dish at levels you might expect to find in the bloodstream after eating one or two cups of açaí pulp and could also cut the growth of colon cancer cells in half.

Unfortunately, as I discuss in my video The Antioxidant Effects of Açaí vs. Apples, subsequent published studies have failed to find such benefits for that particular type of colon cancer, a different type of colon cancer, or an estrogen-receptor negative form of breast cancer. An açaí extract did appear to kill off a line of estrogen-receptor positive breast cancer cells, but to achieve that level of açaí nutrients in your breast, you’d have to eat about 400 cups of açaí pulp.

The problem with many of these petri dish studies is that they use concentrations that you could never realistically achieve in your bloodstream. For example, as you can see at 1:48 in my video, açaí berries may exert a neuroprotective effect, blocking the buildup of amyloid fibers implicated in Alzheimer’s—but only at a dose reached by drinking about 2,000 cups at one time. They may also have an anti-allergy effect or decrease bone loss—at a mere 1,000 cups a day.

In my previous video Clinical Studies on Açaí Berries, I also talked about a clinical study in which subjects were asked to drink less than a cup a day of açaí in a smoothie. They appeared to get significant improvements in blood sugar, insulin levels, and cholesterol. Now, there was no control group and it was a small study, but there’d never been a bigger study trying to replicate it until a study published in 2016.

As you can see at 2:37 in my video, researchers gave subjects the same amount of açaí for the same duration as the previous study, but they found no significant improvements in blood sugars, insulin, or cholesterol. Why did this study fail to show the benefits seen in the first study? Well, this study was publicly funded with “no conflicts of interest,” while the first study was funded by an açaí company, which always makes you suspect that perhaps it was somehow designed to get the desired result. And, indeed, the participants in that first study were not just given açaí smoothies, but they were explicitly told to avoid processed meat, “for example bacon and hot dogs.” No wonder their numbers looked better at the end of the month. Now, the new study did find a decrease in markers of oxidative stress in the participants’ bloodstreams, a sign of how rich in antioxidants açaí berries can be.

Those who hock supplements love to talk about how açaí consumption can “triple antioxidant capacity” of your blood. And, if you look at the study they cite, you’ll find that the antioxidant capacity of participants’ blood did actually triple after eating açaí—but the same or even better tripling was achieved after consuming just plain applesauce, which the researchers used as a control that happens to be significantly cheaper than açaí berries or supplements. You can see the graph at 3:42 in my video.

A new study has shown significant improvements in artery function after eating açaí berries, but are they any more effective than other common fruits and vegetables? You can learn more about that in my video The Benefits of Açaí vs. Blueberries for Artery Function.


What’s so great about antioxidants? Check out:

Where else can you get them? See Flashback Friday: Antioxidants in a Pinch and Antioxidant Power of Plants vs. Animal Foods.

What are the nutritional aspects of those grub-kabobs? See Bug Appétit: Barriers to Entomophagy and Good Grub: The Healthiest Meat.

In health,

Michael Greger, M.D.

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

Topical Green Tea for Acne and Fungal Infections

Which plant should we use for which skin disease? That’s the topic of my video Natural Treatment for Acne and Fungal Infections. Thousands of studies have been published to date about the health effects of green tea, but it wasn’t until fairly recently that researchers began to look at the possibility of using green tea for the prevention and treatment of infections. Patents have been taken out on the antibacterial, antifungal, and antiviral properties of tea. Let’s review some of the evidence.

In terms of fungal infections, green tea compounds have demonstrated “potent antifungal activity” against the primary cause of athlete’s foot, fungal nail infections, jock itch, and ringworm—comparable, in some cases, to powerful antifungal drugs like fluconazole. This was shown in a petri dish, though. How about a green tea footbath for athlete’s foot fungus between the toes? Evidently, tea leaves were once used as a folk remedy for the fungus, so why not put it to the test? Indeed, a once-a-day, 15-minute dilute green tea footbath led to a significant improvement in symptoms compared to controls.

Green tea baths also appeared to help with fungus-associated atopic dermatitis, though there was no control group in that study, and a full-strength green tea may help clear candida yeast from poorly cleaned dentures. What about the bacteria that cause plaque and gingivitis? Even a 2% green tea mouthwash was found to be effective. Yes, you should be able to control plaque just with proper brushing and flossing—with an emphasis on “proper.” Most people don’t brush for the recommended four minutes a day, so a dilute green tea mouthwash may help.

In terms of plaque bacteria-killing ability, green tea was beaten out by a “garlic with lime mouth rinse,” but I think I’ll just stick to green tea, especially when green tea appears to not only kill plaque bugs directly but also boost the antibacterial capacity of saliva after you drink it.

What about green tea for acne? Six weeks of a 2% green tea lotion cut the number of pimples by more than half and significantly reduced the severity, as you can see at 2:48 in my video, making it a cheap, effective treatment for acne.

Impetigo is another bacterial skin infection that can affect the face, but a tea ointment can affect an 80 percent cure rate, on par with antibiotics given topically or orally.

What about bladder infections? We know a certain concentration of green tea compounds can kill the type of E. coli that causes urinary tract infections. The question then becomes how much tea do you have to drink to achieve those concentrations in your bladder? Not much, it turns out. Just one cup of tea might have an effect, but you may need to space out multiple cups over the day because it gets cleared out of your system within about eight hours, as you can see at 3:45 in my video.

So, where do we stand now? The test tube data look promising, but there has yet to be a single study to put it to the test. At this point, green tea should just be used as an adjunct therapy for bladder infections. But, with emerging multidrug-resistant organisms, green tea certainly holds potential.

Wait a moment. If green tea is so good at killing bacteria, might we be killing the good bacteria in our gut when we drink it? No. That’s what’s so amazing. “It has also been shown that green tea has no effect over intestinal flora, which is a great advantage against other bactericidal [bacteria-killing] agents.” But that may not actually be true. Drinking green tea may actually boost the levels of our good bacteria by acting as a prebiotic, thereby improving the colon environment, so it may actually have some effect on our gut flora after all, but it appears to be all good.


Drinking tea with meals may impair iron absorption, so it’s better to drink it between meals. For more on green tea, one of my favorite beverages, along with water and hibiscus tea, see:

For more on acne, check out:

In health,

Michael Greger, M.D.

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

The Flint Lead Crisis May Be the Tip of the Iceberg

Back in the 1960s, a Pulitzer prize-winning scientist described the problem of childhood lead poisoning as “so well defined, so neatly packaged with both causes and cures known, that if we don’t eliminate this social crime, our society deserves all the disasters that have been forecast for it.”

As I discuss in my video Lead in Drinking Water, “We have the knowledge required to redress this social crime. We know where the lead is, how people are exposed, and how it damages health. What we lack is the political will to do what should be done.” Unfortunately, “many policy makers consider the costs of action primarily in economic and financial terms and ignore the costs of inaction on human health and communities’ livelihoods.”

“At this point, most Americans have heard of the avoidable and abject failure of government on the local, state and federal level; environmental authorities; and water company officials”—in fact, failure across the board—“to prevent the mass poisoning of hundreds of children and adults in Flint, Michigan.”

“A government plan to save some money had led public officials to switch the city’s water source from Lake Huron to the Flint River, once the sewer for the auto industry.” Flint citizens “complained that their tap water was foul and discolored. But city, state, and federal officials took no heed.”

Why? Could it have anything to do with the fact that those who complained are “among the poorest in America, mostly African American”?

Officials failed to act for eighteen months, “until a local pediatrician revealed dramatically elevated lead levels in children’s blood.” An investigation didn’t just find fault but highlighted seeming falsification of water-quality results to keep people in the dark.

Though “the specific breed of alleged government corruption” may be unique to Flint, “the end result might not be so rare in the USA—home to an ageing water system.” As the president of the Children’s Health Fund said, “The Pandora’s box is now wide open.” Flint may be only “the tip of an enormous iceberg”—potentially “just one of a great many icebergs.”

“In addition to lead-based paint and residual lead in soil”—found everywhere from leaded gasoline—“a significant source of childhood lead exposure occurs through drinking water as a result of leaching from lead pipes, lead solder, or brass fixtures.” This has been recognized to be a health issue in the United States as early as 1845, a year our flag only had 26 stars. Yet, the use of lead in water pipes and solder was not restricted until the Safe Drinking Water Act Amendment, 141 years later. Was the city you’re living in built before 1986 when the amendment was passed? Today, the “exact number of lead water pipes currently in use is not clear” as about one in three cities surveyed shrugged their shoulders, “not being able to state how much lead piping exists.”

There are anti-corrosion chemicals you can add to tap water to try to keep the lead in the pipes. Flint could have done that, but it could have cost about $100 a day. Today, “the cost of repairing the Flint water system is estimated at $1.5 billion…”

Let me close with a quote from the heroic pediatrician who blew the whistle, Dr. Hanna-Attisha. She was asked, “What advice would you have for other physicians taking on a whistle-blower role?” She replied, “This is our job. This is why we went to medical school—to help people.”

Wasn’t there lead in paint, too, for the longest time? Yes, and that’s the subject of my video How the Lead Paint Industry Got Away with It. And what about leaded gasoline? How many of you remember going to the pumps and seeing the choice between leaded and unleaded? That’s the subject of How the Leaded Gas Industry Got Away with It.


I also get into what the effects are and what we can do about it. Check out:

In health,

Michael Greger, M.D.

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