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Tag: flavonoids

  • Boosting BDNF Levels in Our Brain to Treat Depression  | NutritionFacts.org

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    We can raise BDNF levels in our brain by fasting and exercising, as well as by eating and avoiding certain foods.

    There is accumulating evidence that brain-derived neurotrophic factor (BDNF) may be playing a role in human depression. BDNF controls the growth of new nerve cells. “So, low levels of this peptide could lead to an atrophy of specific brain areas such as the amygdala and the hippocampus, as it has been observed among depressed patients.” That may be one of the reasons that exercise is so good for our brains. Start an hour-a-day exercise regimen, and, within three months, there can be a quadrupling of BDNF release from our brain, as seen below and at 0:35 in my video How to Boost Brain BDNF Levels for Depression Treatment.

    This makes sense. Any time we were desperate to catch prey (or desperate not to become prey ourselves), we needed to be cognitively sharp. So, when we’re fasting, exercising, or in a negative calorie balance, our brain starts churning out BDNF to make sure we’re firing on all cylinders. Of course, Big Pharma is eager to create drugs to mimic this effect, but is there any way to boost BDNF naturally? Yes, I just said it: fasting and exercising. Is there anything we can add to our diet to boost BDNF?

    Higher intakes of dietary flavonoids appear to be protectively associated with symptoms of depression. The Harvard Nurses’ Health Study followed tens of thousands of women for years and found that those who were consuming the most flavonoids appeared to reduce their risk of becoming depressed. Flavonoids occur naturally in plants, so there’s a substantial amount in a variety of healthy foods. But how do we know the benefits are from the flavonoids and not just from eating more healthfully in general? We put it to the test.

    Some fruits and vegetables have more flavonoids than others. As shown below and at 1:51 in my video, apples have more than apricots, plums more than peaches, red cabbage more than white, and kale more than cucumbers. Researchers randomized people into one of three groups: more high-flavonoid fruits and vegetables, more low-flavonoid fruits and vegetables, or no extra fruits and vegetables at all. After 18 weeks, only the high-flavonoid group got a significant boost in BDNF levels, which corresponded with an improvement in cognitive performance. The BDNF boost may help explain why each additional daily serving of fruits or vegetables is associated with a 3 percent decrease in the risk of depression. 

    What’s more, as seen here and at 2:27 in my video, a teaspoon a day of the spice turmeric may boost BNDF levels by more than 50 percent within a month. This is consistent with the other randomized controlled trials that have so far been done. 

    Nuts may help, too. In the PREDIMED study, where people were randomized to receive weekly batches of nuts or extra-virgin olive oil, the nut group lowered their risk of having low BDNF levels by 78 percent, as shown below and at 2:46.

    And BDNF is not implicated only in depression, but schizophrenia. When individuals with schizophrenia underwent a 12-week exercise program, they got a significant boost in their BDNF levels, which led the researchers to “suggest that exercise-induced modulation of BDNF may play an important role in developing non-pharmacological treatment for chronic schizophrenic patients.”

    What about schizophrenia symptoms? Thirty individuals with schizophrenia were randomized to ramp up to 40 minutes of aerobic exercise three times a week or not, and there did appear to be an improvement in psychiatric symptoms, such as hallucinations, as well as an increase in their quality of life, with exercise. In fact, researchers could actually visualize what happened in their brains. Loss of brain volume in a certain region appears to be a feature of schizophrenia, but 30 minutes of exercise, three times a week, resulted in an increase of up to 20 percent in the size of that region within three months, as seen here and at 3:46 in my video. 

    Caloric restriction may also increase BDNF levels in people with schizophrenia. So, researchers didn’t just have study participants eat less, but more healthfully, too—less saturated fat and sugar, and more fruits and veggies. The study was like the Soviet fasting trials for schizophrenia that reported truly unbelievable results, supposedly restoring people to function, and described fasting as “an unparalleled achievement in the treatment of schizophrenia”—but part of the problem is that the diagnostic system the Soviets used is completely different than ours, making any results hard to interpret. There was a subgroup that seemed to correspond to the Western definition, but they still reported 40 to 60 percent improvement rates from fasting, but fasting wasn’t all they did. After the participants fasted for up to a month, they were put on a meat- and egg-free diet. So, when the researchers reported these remarkable effects even years later, they were for those individuals who stuck with the meat- and egg-free diet. Evidently, the closer the diet was followed, the better the effect, and those who broke the diet relapsed. The researchers noted: “Not all patients can remain vegetarian, but they must not take meat for at least six months, and then in very small portions.” We know from randomized controlled trials that simply eschewing meat and eggs can improve mental states within just two weeks, so it’s hard to know what role fasting itself played in the reported improvements.

    A single high-fat meal can drop BDNF levels within hours of consumption, and we can prove it’s the fat itself by seeing the same result after injecting fat straight into our veins. Perhaps that helps explain why increased consumption of saturated fats in a high-fat diet may contribute to brain dysfunction—that is, neurodegenerative diseases, long-term memory loss, and cognitive impairment. It may also help explain why the standard American diet has been linked to a higher risk of depression, as dietary factors modulate the levels of brain-derived neurotrophic factor.

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    Michael Greger M.D. FACLM

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  • Eating with Hypothyroidism and Hyperthyroidism  | NutritionFacts.org

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    Is the apparent protection of plant-based diets for thyroid health due to the exclusion of animal foods, the benefits of plant foods, or both?

    Several autoimmune diseases affect the thyroid gland, and Graves’ disease and Hashimoto’s thyroiditis are the most common. Graves’ disease results in hyperthyroidism, an overactive thyroid gland. Though slaughter plants are supposed to remove animals’ thyroid glands as they “shall not be used for human food,” should some neck meat slip in, you can suffer a similar syndrome called Hamburger thyrotoxicosis. That isn’t from your body making too much thyroid hormone, though. Rather, it’s from your body eating too much thyroid hormone. Graves’ disease is much more common, and meat-free diets may be able to help with both diseases, as plant-based diets may be associated with a low prevalence of autoimmune disease in general, as observed, for example, in rural sub-Saharan Africa. Maybe it’s because plants are packed with “high amounts of antioxidants, possible protective factors against autoimmune disease,” or because they’re packed with anti-inflammatory compounds. After all, “consuming whole, plant-based foods is synonymous with an anti-inflammatory diet.” But you don’t know until you put it to the test.

    It turns out that the “exclusion of all animal foods was associated with half the prevalence of hyperthyroidism compared with omnivorous diets. Lacto-ovo [dairy-and-egg] and pesco [fish] vegetarian diets were associated with intermediate protection.” But, for those eating strictly plant-based, there is a 52 percent lower odds of hyperthyroidism.

    As I discuss in my video The Best Diet for Hypothyroidism and Hyperthyroidism, this apparent protection “may be due to the exclusion of animal foods, the [beneficial] effects of plant foods, or both. Animal foods like meat, eggs, and dairy products may contain high oestrogen concentrations, which have been linked to autoimmunity in cell and animal studies.” Or it could be because the decrease in animal protein by excluding animal foods may downregulate IGF-1, which is not just a cancer-promoting growth hormone, but may play a role in autoimmune diseases. The protection could also come from the goodness in plants that may “protect cells against autoimmune processes,” like the polyphenol phytochemicals, such as flavonoids found in plant foods. Maybe it’s because environmental toxins build up in the food chain. For example, fish contaminated with industrial pollutants, like PCBs, are associated with an increased frequency of thyroid disorders.

    But what about the other autoimmune thyroid disease, Hashimoto’s thyroiditis, which, assuming you’re getting enough iodine, is the primary cause of hypothyroidism, an underactive thyroid gland? Graves’ disease wasn’t the only autoimmune disorder that was rare or virtually unknown among those living in rural sub-Saharan Africa, eating near-vegan diets. They also appeared to have less Hashimoto’s.

    There is evidence that those with Hashimoto’s have compromised antioxidant status, but we don’t know if it’s cause or effect. But if you look at the dietary factors associated with blood levels of autoimmune anti-thyroid antibodies, animal fats seem to be associated with higher levels, whereas vegetables and other plant foods are associated with lower levels. So, again, anti-inflammatory diets may be useful. It’s no surprise, as Hashimoto’s is an inflammatory disease—that’s what thyroiditis means: inflammation of the thyroid gland.

    Another possibility is the reduction in intake of methionine, an amino acid concentrated in animal protein, thought to be one reason why “regular consumption of whole-food vegan diets is likely to have a favourable influence on longevity through decreasing the risk of cancer, coronary [heart] disease, and diabetes.” Methionine restriction improves thyroid function in mice, but it has yet to be put to the test for Hashimoto’s in humans.

    If you compare the poop of patients with Hashimoto’s to controls, the condition appears to be related to a clear reduction in the concentration of Prevotella species. Prevotella are good fiber-eating bugs known to enhance anti-inflammatory activities. Decreased Prevotella levels are also something you see in other autoimmune conditions, such as multiple sclerosis and type 1 diabetes. How do you get more Prevotella? Eat more plants. If a vegetarian goes on a diet of meat, eggs, and dairy, within as few as four days, their levels can drop. So, one would expect those eating plant-based diets to have less Hashimoto’s, but in a previous video, I expressed concern about insufficient iodine intake, which could also lead to hypothyroidism. So, which is it? Let’s find out.

    “In conclusion, a vegan diet tended to be associated with lower, not higher, risk of hypothyroid disease.” Why “tended”? The associated protection against hypothyroidism incidence and prevalence studies did not reach statistical significance. It wasn’t just because they were slimmer either. The lower risk existed even after controlling for body weight. So, researchers think it might be because animal products may induce inflammation. The question I have is: If someone who already has Hashimoto’s, what happens if they change their diet? That’s exactly what I’ll explore next.

    This is the third in a four-video series on thyroid function. The first two were Are Vegans at Risk for Iodine Deficiency? and Friday Favorites: The Healthiest Natural Source of Iodine.

    Stay tuned for the final video: Diet for Hypothyroidism: A Natural Treatment for Hashimoto’s Disease. 

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    Michael Greger M.D. FACLM

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  • Flavonoid Benefits from Apple Peels  | NutritionFacts.org

    Flavonoid Benefits from Apple Peels  | NutritionFacts.org

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    Peeled apples are pitted head-to-head against unpeeled apples (and spinach) in a test of artery function. 

    Regularly eating apples may contribute to a lower risk of dying prematurely. “Moderate apple consumption,” meaning one or two apples a week, “was associated with a 20% lower risk of all-cause mortality”—that is, dying from all causes put together—“whereas those who ate an apple a day had a 35% lower risk of all-cause mortality compared with women with low apple consumption.” 
     
    You’ll often hear me talking about a lower or higher risk of mortality, but what does that mean? Isn’t the risk of dying 100 percent for everyone, eventually? As you can see in my graph below and at 0:40 in my video Friday Favorites: For Flavonoid Benefits, Don’t Peel Apples, I present some survival curves to help you visualize these concepts. For example, if you follow thousands of older women over time, nearly half succumb over a period of 15 years, but that half includes those who rarely, if ever, ate apples—less than 20 apples a year. Instead, those averaging more like half a small apple a day lived longer; over the same time period, closer to 40 percent or so of them died. And, those who ate one small apple or about a quarter of a large apple a day survived even longer. 

    Why is that the case? It seems to be less the apple of one’s eye than the apple of one’s arteries. Even a fraction of an apple a day is associated with 24 percent lower odds of having severe major artery calcifications, a marker of vascular disease. You may think that’s an obvious benefit since apples are fruits and fruits are healthy, but the effect was not found for pears, oranges, or bananas. 
     
    Both of these studies were done on women, but a similar effect (with apples and onions) was found for men. We think it’s because of the flavonoids, naturally occurring phytonutrients concentrated in apples. As you can see below and at 2:02 in my video, they’re thought to improve artery function and lower blood pressure, leading to improvements in blood flow throughout the body and brain, thereby decreasing the risk of heart disease and strokes. You don’t know, though, until you put it to the test.


    When I first saw a paper on testing flavonoid-rich apples, I assumed they had selectively bred or genetically engineered a special apple. But, no. The high-flavonoid apple was just an apple with its peel, compared to the low-flavonoid apple, which was the exact same apple with its peel removed. After eating the apples, flavonoid levels in the bloodstream shot up over the next three hours in the unpeeled apple group, compared to the peeled group, as you can see below, and at 2:36 in my video. This coincided with significantly improved artery function in the unpeeled apple group compared to the peeled one. The researchers concluded that “the lower risk of CVD [cardiovascular disease] with higher apple consumption is most likely due to the high concentration of flavonoids in the skin which improve endothelial [arterial] function”—though, it could be anything in the peel. All we know is that apple peels are particularly good for us, improving artery function and lowering blood pressure. 
    Even compared to spinach? As you can see in the graph below and at 3:14 in my video, if you give someone about three-quarters of a cup of cooked spinach, their blood pressure drops within two to three hours. If you instead eat an apple with some extra peel thrown in, you get a similar effect. The researchers concluded that apples and spinach almost immediately improve artery function and lower blood pressure. 
    What’s nice about these results is that we’re talking about whole foods, not some supplement or extract. So, easily, “this could be translated into a natural and low-cost method of reducing the cardiovascular risk profile of the general population.” 

    For more about apples, see the topic page and check out the related videos below. 

    What about dried apples? See Dried Apples vs. Cholesterol. What about apple cider vinegar? Check out Flashback Friday: Does Apple Cider Vinegar Help with Weight Loss?. And what about apples going head-to-head with açai berries? See The Antioxidant Effects of Açai vs. Apples.

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    Michael Greger M.D. FACLM

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  • Do Multiple Sclerosis and Alcohol Mix?

    Do Multiple Sclerosis and Alcohol Mix?

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    When it comes to your multiple sclerosis (MS), you want to do what’s best for your body. But you wonder about alcohol. Is it OK to enjoy a drink from time to time? Or is alcohol completely off the table? The answer is a little more complicated than a simple yes or no.

    Don’t Overdo It

    “For most people with MS, the answer is to use alcohol in moderation,” says Jennifer Graves, MD, PhD, associate professor of neurosciences and director of the Neuroimmunology Research Program at the University of California, San Diego.

    According to the U.S. Dietary Guidelines for Americans, that means no more than one drink a day if you’re a woman or two if you’re a man.

    “Regularly having several drinks could worsen neurological damage and function for patients living with MS, but a glass of wine or single beer at dinner is unlikely to cause significant issues,” says Graves.

    Alcohol is neither all good nor all bad. For example, the antioxidants and flavonoids in red wine may actually lower your risk of heart disease, which is a concern when you have MS. But this isn’t a reason to start drinking if you don’t already. These compounds are in other food and drink, says Graves.

    And in case you’re wondering if past alcohol use may have caused your MS, set your worries aside.

    “Based on data available, that’s unlikely,” says Graves.

    Alcohol’s Effect on MS Symptoms

    If you do decide to enjoy an occasional glass of wine or beer, know that it could ramp up certain symptoms of MS. Even one drink can make issues like unsteadiness worse.

    “If you have a lot of trouble with balance, thinking, or memory symptoms from MS, it may be better to avoid alcohol altogether,” says Graves.

    Alcohol can also lead to sleep problems and worsen bladder symptoms. You also raise your risk of other conditions when you drink alcohol, especially if you drink too much. Your chances of certain cancers, high cholesterol, and stroke go up. Some of these conditions can make your MS worse overall, says Graves, so doing what you can to keep them from happening is important.

    Several medications used to treat MS symptoms like pain, headache, insomnia, and depression don’t mix well with alcohol. “Combining these medications with drinks could lead to excessive sedation and health risks,” says Graves.

    Be sure to ask your doctor how your specific treatments might act with alcohol so you know what to look for.

    Short and Sweet

    Remember that everyone with MS is different. Have an honest conversation with your doctor about your habits so you can make smart decisions for yourself.

    It’s likely fine for you to celebrate with a glass of bubbly, add a nice red to your meal, or enjoy a beer while you watch the game. Just know your limits and try your best to stay within them.

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