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:

Can Soy Prevent and Treat Prostate Cancer?

As I discuss in my video The Role of Soy Foods in Prostate Cancer Prevention and Treatment, a compilation of 13 observational studies on soy food consumption and the risk of prostate cancer found that soy foods appear to be “protective.” What are observational studies? As opposed to interventional studies, in observational studies, researchers observe what people are eating but don’t intervene and try to change their diets. In these studies, they observed that men who ate more soy foods had lower rates of prostate cancer, but the problem with observational studies is that there could be confounding factors. For example, “people who choose to eat soy also make other lifestyle decisions that lower the risk of cancer (e.g., lower fat intake, higher vegetable and fruit intake, more frequent exercise),” maybe that is why they have less cancer. Most of the studies tried to control for these other lifestyle factors, but you can’t control for everything. What’s more, most of the studies were done in Asia, so maybe tofu consumption is just a sign of eating a more traditional diet. Is it possible that the reason non-tofu consumers got more cancer is that they had abandoned their traditional diet? If only we could look at a Western population that ate a lot of soy. We can: the Seventh-Day Adventists.

In the 1970s, more than 12,000 Adventist men were asked about their use of soy milk and then were followed for up to 16 years to see who got cancer and who did not. So, what did they find? Frequent consumption of soy milk was associated with a whopping 70 percent reduction of the risk of prostate cancer, as you can see at 1:33 in my video. Similarly, in a multiethnic study that involved a number of groups, soy intake appeared protective in Latinos, too.

Prostate cells carry beta type estrogen receptors, which appear to act as a tumor suppressor, a kind of “gatekeeper…inhibiting invasion, proliferation and…preventing” the prostate cells from turning cancerous. And, those are the receptors targeted by the phytoestrogens in soy, like genistein, which inhibits prostate cancer cell invasion and spread in a petri dish at the kind of levels one might get consuming soy foods. The prevention of metastases is critical, as death from prostate cancer isn’t caused by the original tumor, but its spread throughout the body, which explains why it “is recommended that men with prostate cancer consume soy foods, such as soybeans, tofu, miso and tempeh.”

Wait a moment. Dean Ornish and his colleagues got amazing results, apparently reversing the progression of prostate cancer with a plant-based diet and lifestyle program. Was it because of the soy? Their study didn’t just include a vegan diet, but a vegan diet supplemented with a daily serving of tofu and a soy protein isolate powder. There have been studies showing that men given soy protein powders develop less prostate cancer than the control group, but what was the control group getting? Milk protein powder. Those randomized to the milk group got six times more prostate cancer than the soy group, but was that due to the beneficial effects of soy or the deleterious effects of the dairy? Dairy products are not just associated with getting prostate cancer, but also with dying from prostate cancer. Men diagnosed with prostate cancer who then ate more dairy tended to die sooner, and “both low-fat and high-fat dairy consumption were positively associated with an increased risk of fatal outcome.”

The best study we have on soy protein powder supplementation for prostate cancer patients found no significant benefit, and neither did a series of soy phytoestrogen dietary supplements. But, perhaps that’s because they used isolated soy components rather than a whole soy food. “Taking the whole-food approach may be more efficacious,” but it can be hard to do controlled studies with whole foods: You can make fake pills, but how do you give people placebo tofu?

A group of Australian researchers creatively came up with a specially manufactured bread containing soy grits to compare to a placebo regular bread and gave slices to men diagnosed with prostate cancer awaiting surgery. As you can see at 4:31 in my video, they saw a remarkable difference in just about three weeks time. It was the first study to show that a diet incorporating a whole soy food could favorably affect prostate cancer markers, but you can’t just go out and buy soy grit bread. Another study was a little more practical. Twenty men with prostate cancer who had been treated with radiation or surgery but seemed to be relapsing were asked to drink three cups of regular soy milk a day. The PSA levels in each of the 20 patients were all rising before they started the soy milk, suggesting they had relapsing or metastatic cancer growing inside of them. However, during a year drinking soy milk, 6 out of the 20 subjects got better, 2 got worse, and the remaining 12 remained unchanged, as you can see from 5:02 in my video. So, they concluded that soy food may help in a subset of patients.

Based on all these studies, the results Ornish and his colleagues got were probably due to more than just the soy. Similarly, the low prostate cancer rates in Asia are probably because of more than just the soy, since the lowest rates are also found in parts of Africa, where I don’t think they’re eating a lot of tofu. Indeed, in the multiethnic study, other types of beans besides soy also appeared protective for Latinos and all the groups put together, when looking at the most aggressive forms of prostate cancer. So, the protection associated with plant-based diets may be due to eating a variety of healthy foods. 


That soy milk stat from the Adventist study is astounding. What about fermented soy foods, though? That was the subject of Fermented or Unfermented Soy Foods for Prostate Cancer Prevention?.

Reversing the progression of cancer? See How Not to Die from Cancer.

Given the power of diet, it’s amazing to me how difficult Changing a Man’s Diet After a Prostate Cancer Diagnosis can be. It’s not all or nothing, though. Check out Prostate Cancer Survival: The A/V Ratio.

For soy and breast cancer survival, see Is Soy Healthy for Breast Cancer Survivors?.

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:

No Purveyor of Unhealthy Products Wants the Public to Know the Truth

In 2011, Denmark introduced the world’s first tax on saturated fat. “After only 15 months, however, the fat tax was abolished,” due to massive pressure from farming and food company interests. “Public health advocates are weak in tackling the issues of corporate power…A well-used approach for alcohol, tobacco, and, more recently, food-related corporate interests is to shift the focus away from health. This involves reframing a fat or soft drinks tax as an issue of consumer rights and a debate over the role of the state in ‘nannying’ or restricting people’s choices.” I discuss this in my video The Food Industry Wants the Public Confused About Nutrition.

“The ‘Nanny State’ is a term that is usually used in a pejorative way to discourage governments from introducing legislation or regulation that might undermine the power or actions of industry or individuals…Public health advocacy work is regularly undermined by the ‘Nanny State’ phrase.” But those complaining about the governmental manipulation of people’s choices hypocritically tend to be fine with corporations doing the same thing. One could argue that “public health is being undermined by the ‘Nanny Industry’…[that] uses fear of government regulation to maintain its own dominance, to maintain its profits and to do so at a significant financial and social cost to the community and to public health.”

The tobacco industry offers the classic example, touting “personal responsibility,” which has a certain philosophical appeal. As long as people understand the risks, they should be free to do whatever they want with their bodies. Now, some argue that risk-taking affects others, but if you have the right to put your own life at risk, shouldn’t you have the right to aggrieve your parents, widow your spouse, and orphan your children? Then, there’s the social cost argument. People’s bad decisions can cost the society as a whole, whose tax dollars may have to care for them. “The independent, individualist motorcyclist, helmetless and free on the open road, becomes the most dependent of individuals in the spinal injury ward.”

But, for the sake of argument, let’s forget these spillover effects, the so-called externalities. If someone understands the hazards, shouldn’t they be able to do whatever they want? Well, “first, it assumes individuals can access accurate and balanced information relevant to their decisions…but deliberate industry interference has often created situations where consumers have access only to incomplete and inaccurate information…For decades, tobacco companies successfully suppressed or undermined scientific evidence of smoking’s dangers and down played the public health concerns to which this information gave rise.” Don’t worry your little head, said the nanny companies. “Analyses of documents…have revealed decades of deception and manipulation by the tobacco industry, and confirmed deliberate targeting of…children.” Indeed, it has “marketed and sold [its] lethal products with zeal…and without regard for the human tragedy….”

“The tobacco industry’s deliberate strategy of challenging scientific evidence undermines smokers’ ability to understand the harms smoking poses” and, as such, undermines the whole concept that smoking is a fully informed choice. “Tobacco companies have denied smokers truthful information…yet held smokers [accountable] for incurring diseases that will cause half of them to die prematurely. In contexts such as these, government intervention is vital to protect consumers from predatory industries….”

Is the food industry any different? “The public is bombarded with information and it is hard to tell which is true, which is false and which is merely exaggerated. Foods are sold without clarity about the nutritional content or harmful effects.” Remember how the food industry spent a billion dollars making sure the easy-to-understand traffic-light labeling system on food, which you can see at 4:26 in my video, never saw the light of day and was replaced by indecipherable labeling? That’s ten times more money than the drug industry spends on lobbying in the United States. It’s in the food industry’s interest to have the public confused about nutrition.

How confused are we about nutrition? “Head Start teachers are responsible for providing nutrition education to over 1 million low-income children annually…” When 181 Head Start teachers were put to the test, only about 4 out of the 181 answered at least four of the five nutrition knowledge questions correctly. Most, for example, could not correctly answer the question, “What has the most calories: protein, carbohydrate, or fat?” Not a single teacher could answer all five nutrition questions correctly. While they valued nutrition education, 54 percent “agreed that it was hard to know which nutrition information to believe,” and the food industry wants to keep it that way. A quarter of the teachers did not consume any fruits or vegetables the previous day, though half did have french fries and soda, and a quarter consumed fried meat the day before. Not surprisingly, 55 percent of the teachers were not just overweight but obese.

When even the teachers are confused, something must be done. No purveyor of unhealthy products wants the public to know the truth. “An interesting example comes from the US ‘Fairness Doctrine’ and the tobacco advertising experience of the 1960s. Before tobacco advertising was banned from television in the US, a court ruling in 1967 required that tobacco companies funded one health ad about smoking for every four tobacco TV advertisements they placed. Rather than face this corrective advertising, the tobacco industry took their own advertising off television.” They knew they couldn’t compete with the truth. Just “the threat of corrective advertising even on a one-to-four basis was sufficient to make the tobacco companies withdraw their own advertising.” They needed to keep the public in the dark.

The trans fat story is an excellent example of this. For more on that, see my videos Controversy Over the Trans Fat Ban and Banning Trans Fat in Processed Foods but Not Animal Fat.

Isn’t the Fairness Doctrine example amazing? Just goes to show how powerful the truth can be. If you want to support my efforts to spread evidence-based nutrition, you can donate to our 501c3 nonprofit here. You may also want to support Balanced, an ally organization NutritionFacts.org helped launch to put this evidence into practice.


More tobacco industry parallels can be found in Big Food Using the Tobacco Industry Playbook, American Medical Association Complicity with Big Tobacco, and How Smoking in 1959 Is Like Eating in 2016.

Want to know more about that saturated fat tax idea? See Would Taxing Unhealthy Foods Improve Public Health?.

Also check:

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: