Doesn’t it seem like when it comes to nutrition there are more opinions than facts to go around? Every day we hear new theories about diets, and supplements, and the best foods to eat. My role is to take the mystery out of good nutrition, and look at the science. Welcome to the Nutrition Facts Podcast. I’m your host Dr. Michael Greger. And I’m here to bring you an evidence-based approach to the best way to live a healthier longer life.
Today, we focus on loving our liver. The liver is, among many other functions, a crucial detoxification organ. So what are the best ways to keep it healthy? Let’s start with chlorella. In our first story, chlorella is put to the test for liver disease, cholesterol, and detoxifying carcinogens.
Depression is a debilitating mental disorder with a severe impairment to quality of life.” The drugs don’t work particularly well, and have a bunch of side effects. So, “searching for alternative antidepressant agents with proper efficacy and safety is necessary.” Well, there is this green algae called chlorella that “has been used as a dietary supplement and alternative medicine” in Asia for centuries. Why not put it to the test?
In a randomized controlled trial of chlorella in patients with major depression, subjects were randomized to standard therapy or standard therapy plus 1800 mg of chlorella, which is about three-quarters of a teaspoon a day. And, significant improvements in “physical and cognitive symptoms of depression as well as anxiety.”
Wow! Okay, but what word is missing here? A “randomized controlled trial of chlorella.” What we want is a randomized placebo-controlled trial. Here, they compared chlorella to nothing. Half got some special treatment, and the other half got nothing; the perfect set-up for the placebo effect, especially when the measured outcomes are mostly just about how they’re subjectively feeling. Now, you could argue “Look, that much chlorella would only cost about 10 cents a day. It’s healthy for you anyway, and depression is such a serious disease. Why not just give it a try?” Okay, but I’d still like to know if it actually works or not.
This other study on chlorella suffered from a similar problem, but at least had an objective quantifiable outcome: a “significant decrease” in liver inflammation. But, this study had no control group at all. So, maybe they would have just gotten better on their own for some reason. There’s never been a randomized, double-blind, placebo-controlled trial of chlorella for liver disease, until now.
And, not just any liver disease: “non-alcoholic fatty liver disease,” which, thanks to the obesity pandemic, now affects one in four people on Earth. Let’s see if 1,200 mg of chlorella a day will help. That’s about a half-teaspoon, closer to just a nickel a day, and significant drops in liver inflammation, perhaps because they lost significantly more weight (about a pound a week over the eight weeks), which would explain the significant improvement in fasting blood sugars. They conclude that chlorella has “significant weight-reducing effects” with “meaningful improvements” in liver function.
How about a double-blinded, randomized, placebo-controlled study of chlorella for cholesterol? “Compared with the control group, the chlorella group exhibited remarkable changes in total cholesterol.” Wow, how much? Only 1.6%. What?! And, note they said total cholesterol. If you look at what really matters, LDL cholesterol, no effect whatsoever.
Thankfully, that’s not what other studies found. A meta-analysis of 19 randomized controlled trials of chlorella for cholesterol, involving hundreds of subjects, found that those taking chlorella did drop their LDL, eight points on average, and even dropped their blood pressure a few points. Four grams or more a day for at least eight weeks seems to be the magic formula. That would be about two teaspoons a day. That’s a lot of chlorella, but if you can find a palatable way to take it, it might help.
This is the latest: a “dietary cholesterol challenge.” They had people eat three eggs a day with or without a few spoonfuls of chlorella. “In this double blind, randomized, placebo-controlled study, 34 participants ingested 510 mg of dietary cholesterol from three eggs concomitantly with a dose of Chlorella or a matched placebo for 4 weeks.” Just eating the eggs alone, a 14% rise in LDL cholesterol. But, with the chlorella significantly less. Therefore, chlorella can be playing “a useful role in maintaining healthy blood cholesterol levels.” Another way would be to not eat three eggs a day.
That reminds me of this other study “to assess the ability of Chlorella to detoxify carcinogenic heterocyclic amines” the cancer-causing chemicals created when you fry, bake, broil, or barbecue meat. The chlorella did seem to lower the levels of one of the cooked-meat carcinogens flowing through their bodies, but didn’t quite reach statistical significance.
Or, what about “polycyclic aromatic hydrocarbons”, another class of cancer-causing compounds found particularly in smoked meats and cigarettes, that “include numerous genotoxic DNA-damaging carcinogens”? And, again, chlorella did seem to lower levels, but not significantly so. Still, if you’re going to sit down to ham and eggs for breakfast or something, make sure to add lots of chlorella and make them green eggs and ham.
Next we look at the wondrous properties of ground ginger powder for weight loss and nonalcoholic fatty liver disease.
Ginger has been used in India and China to treat illnesses for thousands of years. But, they also used mercury, so that doesn’t really tell you much. That’s what we have science for. But, when you see titles in the medical literature on the “beneficial effects of ginger on obesity,” for example, you may not be aware they’re talking about the beneficial effects of ginger on fat rats. Wait; why don’t they just do human clinical studies? The “lack of clinical studies may be attributed to for example ethical issues and limited commercial support.” Limited commercial support I can see. Ginger is dirt cheap; who’s going to pay for the study. But ethical issues? We’re just talking about feeding people some ginger!
But maybe ginger consumption is just a marker of more traditional, less Westernized, junk food diets. I mean, you don’t know until you put it to the test.
A randomized, controlled trial to assess “the effects of a hot ginger beverage.” By which they just meant two grams of ginger powder in a cup of hot water. So, about one teaspoon of ground ginger stirred into a teacup of hot water. That’s about five cents worth of ginger. And after the ginger, the participants reported feeling significantly less hungry. And, in response to the question, “How much do you think you could eat?” described “lower prospective food intake.”
Now the control was just “hot water alone,” so the participants knew when they were getting the ginger. So, there could be a placebo effect. They considered just stuffing the ginger into capsules to do a double-blinded study, but they think part of the effect of ginger may actually be through taste receptors on the tongue. So, they didn’t want to interfere with that.
Not all the effects were just subjective, though. Four hours after drinking, the metabolic rate in the ginger group was elevated compared to control though in a previous study, when fresh ginger was added to a meal, there was no bump in metabolic rate. The researchers suggest this may be “due to the different method of ginger administration” giving fresh instead of dried. And, there are dehydration products that form when you dry ginger that may have unique properties.
Now although satiety and fullness were greater with ginger compared to control, the researchers didn’t then follow the participants to see if they like actually ate less for lunch. The problem is, there’s never been a randomized, double-blind, placebo-controlled study of that much ginger and weight loss until now.
Twelve weeks of that same teaspoon of ginger powder a day, but this time hidden in capsules. And, consumption of ginger for 12 weeks significantly reduced body mass index. No change in the placebo group, but a drop in the ginger group. Though body fat estimates didn’t really change, which is kind of the whole point.
What about using ginger to pull fat out of specific organs, like the liver? Evidently, “treatment with ginger ameliorates fructose-induced fatty liver in rats.” You know what else would have worked? Not feeding them so much sugar in the first place. But there’s never been a human you know where this is going, until now. “Ginger supplementation in nonalcoholic fatty liver disease: a randomized, double-blind, placebo-controlled study”; a teaspoon of ginger a day or placebo for 12 weeks.
They were all told “to limit their dietary cholesterol intake”—I’ve got a video on why that’s important—and get more fiber and exercise. So, even the placebo group should improve. But did the ginger group do any better? Yes, “daily consumption” of just that teaspoon of ground ginger a day “resulted in a significant decrease in inflammatory marker levels,” and improvements in liver function tests, and a drop in liver fat. All for five cents worth of ginger powder a day.
And, what are the side effects? A few gingery burps? I searched for downsides, and didn’t find any other than, of course, “ginger paralysis.” What?! “In 1930, thousands of Americans were poisoned” by a ginger extract. First of all, who drinks ginger extract? Oh, 1930, it was Prohibition, so they bought ginger extract as a legal way to get their hands on alcohol. “Little did he realize that the bootleggers had been taking advantage of the demand,” swapped in a cheaper ginger substitute, a varnish compound, in order to make greater profits. The moral of the story being don’t drink varnish.
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