Have you ever noticed that every month seems to bring a trendy new diet? And yet obesity rates continue to rise and with it a growing number of health problems. That’s why I wrote my new book How Not to Diet. Check it out at your local public library. Welcome to the Nutrition Facts Podcast. I’m your host Dr. Michael Greger.
It’s time for the nutrition facts grab bag, where we look at the latest science on a whole variety of topics. First up we look at the exotic star fruit. Did you know it contains a neurotoxin called caramboxin that can cause irreversible brain damage at high enough doses?
Someone walks into the ER with intractable hiccups. One of the questions the emergency room physician should ask is, “Have you been eating star fruit?”
“Excessive consumption of star fruit has been associated with the development of oxalate kidney damage.” Less than a cup of star fruit juice or three whole fruits, they’re not that big, can result in “acute star fruit nephrotoxicity.” “Ingestion of even modest quantities of star fruits can produce” kidney problems; so, it is essential to educate the public to avoid consuming star fruit, “especially on an empty stomach or in a dehydrated state” to prevent star fruit nephrotoxicity.
But, what about the neurotoxicity? We’ve known for more than a quarter century now about the neurotoxic effects, but few seem to be familiar with the syndrome. It starts, most commonly, with hiccups, but then can rapidly worsen, especially in those with compromised kidney function to start out with. Why? Because the “fruit contains a powerful neurotoxin that can accumulate in blood, cross the blood–brain barrier and eventually cause irreversible brain damage.” The toxin itself, named caramboxin, is normally excreted by the kidneys; and so, is especially toxic to those with renal insufficiency, compromised kidney function, so much so that for those with severe chronic kidney disease, a single star fruit can put someone in seizures within three hours, a coma, and then death within three days.
In a series of about a hundred cases of toxicity, consumption ranged between just a half of a star fruit up to 50, with an average of about four, but most of those had some sort of pre-existing kidney disease. The average number of star fruits eaten by the normal kidney function group before their toxic dose was more like 15. So, people with normal kidney function may be more likely to suffer from kidney damage than brain damage, which starts at down around four star fruit.
The bottom line is that those with chronic kidney disease should avoid star fruit to avoid severe intoxication. In Brazil, where the fruit is popular, there are actually laws to alert people about the risks. Because of the neurotoxins, star fruit should be prohibited for patients with chronic kidney disease, and even those with normal kidney function may want to avoid the fruit. Just something to think about, before you reach for the stars.
In our next story, we look at the industry’s response to the charge that breakfast cereals are too sugary.
In 1941, the American Medical Association’s Council on Foods and Nutrition was presented with a new product, Vi-Chocolin, a vitamin-fortified chocolate bar, “offered ostensibly as a product of high nutritive value, but in reality, intended for promotion to the public as a kind of vitaminized candy.” Surely something like that couldn’t happen today! But that’s the entire sugary cereal industry’s business model. Twelve vitamins and minerals. Way better than those marshmallow Froot Loops with just a measly 11.
Nutrients are added to breakfast cereals “as a marketing gimmick to create an aura of healthfulness.” If those same nutrients were added to soda, would we feed our kids Coke for breakfast? We might as well spray cotton candy with vitamins too. As one medical journal editorial read, “Adding vitamins and minerals to sugary cereals is worse than useless. The subtle message is that it is somehow safe to eat more.”
General Mills’ “Grow up strong with Big G kids’ cereals” ad campaign featured products like Lucky Charms, Trix, and Cocoa Puffs. That’s like the dairy industry promoting ice cream to get your calcium. Kids who eat pre-sweetened breakfast cereals may get more than 20 percent of their daily calories from added sugar. Most sugar in the American diet comes from beverages like soda, but breakfast cereals represent the third-largest food source of added sugars in the diets of children and adolescents, wedged between candy and ice cream. On a per-serving basis, there is more added sugar in a cereal like Frosted Flakes than there is in frosted chocolate cake, brownies, or a frosted doughnut.
Kellogg and General Mills argue that breakfast cereals only contribute a “relatively small amount of sugar” to the diets of children; less than soda, for example. This is a perfect example of a psychological phenomenon known as “diffusion of responsibility.” That’s like every restaurant in the country arguing that their individual contribution to the problem of secondhand smoke is relatively tiny, and therefore they should be exempted from a smoking ban. Each and every source of added sugar should be reduced.
The industry argues that most of their cereals have less than 10 grams of sugar per serving, but when Consumer Reports measured how much youngsters actually poured, they were found to serve themselves about 50 percent more than the suggested serving size for most of the tested cereals. The average portion of Frosted Flakes they poured for themselves contained 18 grams of sugar (4.5 teaspoons, or 6 sugar packets worth). It’s been estimated that “a child eating just one serving per day of the average children’s cereal would consume close to 10 pounds of sugar in a year, nearly 1,000 spoonfuls of sugar.”
General Mills offers the “Mary Poppins defense,” arguing that it’s those spoonfuls of sugar that can help the medicine go down, explaining that “if sugar is removed from bran cereal, it would have the consistency of sawdust.” If we couldn’t add sugar, our cereals would be unpalatable. If one has to add sugar to a product to make it edible, that should be a sign. That’s a characteristic of so-called “ultra-processed” foods, where you have to pack them full of things like sugar, salt, and flavorings since they have had “their natural intrinsic flavors processed out and you have to mask any unpleasantries in the final product.”
The president of the Cereal Institute has argued that without sugary cereals, kids might not eat breakfast at all, similar to dairy industry arguments that “removing chocolate milk from school cafeterias” would risk kids skipping lunch. He also stressed we must consider the alternatives. As Kellogg’s director of nutrition once put it: “I would suggest that Fruit Loops as a snack are much better than potato chips or a sweet roll.” You know there’s a problem when the only way to make your product look good is to compare it to Pringles and Cinnabon.
Finally today, we examine how elevated levels of pro-inflammatory, aging-associated oxylipins can be normalized by eating ground flax seed.
Previously, I’ve explored the potent antihypertensive effect of dietary flaxseed in hypertensive patients. This was a double-blind, randomized, placebo-controlled trial where they disguised ground flax seed in baked goods, versus like flax-free placebo muffins, and got an extraordinary drop in high blood pressures. As you can imagine, the flax seed industry was overjoyed, praising the impressive findings, as was I. After all, high blood pressure is the single largest risk factor for death on the planet earth. Yes, we give people medications, lots and lots of medications, but most people don’t take them, as in 9 out of 10 people take less than 80 percent of their prescribed blood pressure pills. Just 8 percent.
It’s not difficult to understand why. “Patients are asked to follow an inconvenient and potentially costly regimen, which will likely have a detrimental effect on their health-related quality of life to treat a mostly asymptomatic condition.” So, they may feel worse instead of better, due to the side effects. The answer, then, is to give them more drugs to counteract the effects of the first drugs like giving men Viagra to counteract the erectile dysfunction caused by their blood pressure pills.
How about using a dietary strategy instead, especially if it can be just as effective? And indeed, the drop in blood pressures they got in the flax seed study “was greater than the average decrease observed with the standard dose of anti-hypertensive drugs.” And, flaxseeds are cheaper too, compared to even single medications, and most patients are on multiple drugs. And it has good side effects beyond their anti-hypertensive actions but not all good. Taking tablespoons of flax seed a day is a lot of fiber for people who have been living off of cheeseburgers and milkshakes their whole lives, and it can take a little while for your gut bacteria to adjust to the new bounty. So, people who start out with low-fiber diets may want to take it slow at first.
Not all studies have shown significant blood pressure-lowering effects. There have been over a dozen trials by now, involving more than a thousand subjects. And yes, put them all together, and overall, there were significant reductions in both systolic and diastolic blood pressures, the upper and lower numbers, following supplementation with various flax seed products. None were as dramatic as that six-month trial. The longer trials tended to show better results, and some of the trials just used flax seed oil or some kind of flax seed extract. The thought is that the whole is greater than the sum of its parts. “Each of the components of interest within flaxseed, the omega-3’s, the cancer-fighting lignans, all the soluble fiber and plant proteins, all contribute towards the blood pressure reduction.” Okay, but how? Why? What’s the mechanism?
Some common blood-pressure medications, like Norvasc or Procardia, work by reducing the ability of the heart to contract, or slowing the heart down. And so, it’s possible that’s how flaxseed works too. But no. “Dietary flaxseed reduces blood pressure without cardiac involvement but rather, through changes in plasma oxylipins.” What are oxylipins?
“Oxylipins are a group of fatty acid metabolites” involved in inflammation, and as a result, have been implicated in many pro-inflammatory conditions including cardiovascular disease and aging. “The best characterized oxylipins in relation to cardiovascular disease are derived from the long chain omega-6 fatty acid known as arachidonic acid, found preformed in animal products, particularly chicken and eggs,” and can be made inside the body from junky omega-6 rich oils, such as cottonseed oil. But, elevated levels of pro-inflammatory oxylipins in older subjects are normalized by flax seed consumption.
That’s how we think flax seed consumption reduces blood pressure in patients with hypertension: by inhibiting the enzyme that makes these pro-inflammatory oxylipins. I’ll spare you from the acronym overload, but basically, eating flax seeds inhibits the activity of the enzyme that makes these pro-inflammatory oxylipins, called leukotoxin diols, which in turn may lower blood pressure. “Identifying the molecular mechanisms adds confidence to the antihypertensive actions of dietary flaxseed.”
But that’s not all oxylipins do. Oxylipins may play a role in the aging process. But we may be able to beneficially disrupt these biological changes associated with inflammation and aging with a nutritional intervention like flax seed. Older adults (around age 50) have higher levels of this arachidonic acid-derived oxylipins, compared to younger adults (around age 20). “These elevated concentrations of pro-inflammatory oxylipins in the older age group may help explain the higher levels of inflammation in older versus younger individuals.” As we get older, we’re more likely to be stricken with inflammatory conditions like arthritis; and so, this elevation of pro-inflammatory oxylipins may predispose individuals to chronic disease conditions. But what if you took those older adults and gave them muffins, ground flax seed-containing muffins?
Four weeks later, their levels dropped down to like 20-year-old levels, demonstrating “that a potential therapeutic strategy to correct the deleterious pro-inflammatory oxylipin profile is via a dietary supplementation with flax.”
We would love it if you could share with us your stories about reinventing your health through evidence-based nutrition. Go to NutritionFacts.org/testimonials. We may share it on our social media to help inspire others.
To see any graphs charts, graphics, images or studies mentioned here, please go to the Nutrition Facts Podcast landing page. There you’ll find all the detailed information you need plus links to all of the sources we cite for each of these topics.
For recipes, check out my How Not to Diet Cookbook. It’s beautifully designed, with more than 100 recipes for delicious and nutritious meals. And all proceeds I receive from the sales of my books goes to charity.
NutritionFacts.org is a nonprofit, science-based public service, where you can sign up for free daily updates on the latest in nutrition research via bite-sized videos and articles.
Everything on the website is free. There’s no ads, no corporate sponsorship. It’s strictly non-commercial. I’m not selling anything. I just put it up as a public service, as a labor of love, as a tribute to my grandmother whose own life was saved with evidence-based nutrition. Thanks for listening to Nutrition Facts. I’m your host, Dr. Michael Greger.