Inhibiting Platelet Activation with Tomato Seeds

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In the prevention of cardiovascular disease, the consumption of fruits and vegetables is crucial. Preventing the oxidation of cholesterol may be one of the mechanisms by which fruits and vegetables reduce the risk of heart attacks and strokes. However, hyperactivity of platelets is also critically important in the pathogenesis of cardiovascular disease, as I've covered before (See Inhibiting Platelet Aggregation with Berries).

In recent years, it has been shown that platelets are not only involved in the arterial clotting process, but also that they play an active role in the inflammatory process of atherosclerosis from childhood. By the end of our teens, atherosclerotic lesions are present in most people living in industrialized societies, and so suppressing the over-activity of platelets may be beneficial not only for heart disease, but for cancer, allergies, and diseases for which inflammation plays a major role.

The antioxidant properties of fruits and veggies are well known. However, their anti-clotting effects on platelets are less known. Preliminary studies have demonstrated the platelet activation suppressing activity of a variety of fruits and vegetables. They suppress platelet activation so well that they can actually mess up platelet function tests. And, the effects are so long-lasting that fasting the morning of your blood test may not be sufficient.

Out of 16 different fruits tested, tomatoes came out number one. The anti-platelet activation components in tomatoes are water soluble, so we don't have to eat them with fat; heat stable, meaning we can cook tomatoes without losing the benefits; and concentrated in the yellow fluid around the seeds. This is why tomato pomace beat out tomato juice, sauce, or ketchup. Pomace is basically the seeds and the peel, which the industry throws away, and it may be the healthiest part. And the more tomato seeds the better. But this study was measuring platelet activation in a petri dish. Grapefruit came in number two here, and grapefruit juice at least didn't appear to help when people actually drank it. Would drinking tomato juice actually help?

Platelets of patients with diabetes are characterized by intensified activation, so 20 diabetics were asked to drink a daily cup of tomato juice for three weeks or a tomato-flavored placebo beverage, and there was a significant drop in platelet activation.

A study done by the Rowett Research Institute, highlighted in my video, Inhibiting Platelet Activation with Tomato Seeds, found this works in healthy people as well. Within three hours of consumption, two tomatoes lowered platelet activation, and six tomatoes worked even better. Also, the effects were more wide-ranging than those of aspirin in that the tomatoes targeted multiple pathways of platelet activation.

About one in four people are aspirin resistant, meaning aspirin doesn't work to calm down their platelets, whereas only 3% of study subjects were found to be tomato resistant.

This finding indicates an advantage of the tomato extract's broad antiplatelet activity profile over single-target drugs such as aspirin. Also, when researchers stuck tubes into people while they were eating tomatoes, they found no changes in blood clotting times, implying that supplementation with tomatoes should not result in a prolonged bleeding times, so one might get the best of both worlds: less platelet activation without the bleeding risk. But if tomatoes don't thin our blood, do they work?

Researchers out of North Carolina State University report that, "consumption of tomato products has been found to be protectively correlated with a lower incidence of acute coronary events, less development of early atherosclerosis, and lower mortality from heart disease."

If you don't like tomatoes, kiwifruit recently beat them out in a test tube study of platelet activation. Strawberries may help too, but we have data showing kiwis may actually work in people, and two kiwis appeared to work just as well as three kiwis. It appears to work for green-on-the-inside kiwifruit; and for yellow-on-the-inside kiwifruit. In this case, though, one a day seemed to help whereas two-a-day did not, which seems a little strange. And there haven't been any studies to see if kiwifruit eaters actually have fewer strokes and heart attacks, so the best evidence for a dietary intervention to decrease platelet activation currently rests with tomatoes.

One of my favorite videos, The Tomato Effect, is actually not about tomatoes at all, but talks about the power of a diet composed entirely of plants to combat the heart disease epidemic. After all, Heart Disease Starts in Childhood.

I do have some others that really do touch on tomatoes, though:

More on kiwis here:

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

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What To Do if You Suspect Gluten Problems

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Symptoms of gluten sensitivity include irritable bowel type symptoms such as bloating, abdominal pain, and changes in bowel habits, as well as systemic manifestations such as brain fog, headache, fatigue, depression, joint and muscle aches, numbness in the extremities, skin rash, or anemia. I previously discussed why people who suspect they might be gluten sensitive should not go on a gluten-free diet. But if that's true, what should they do?

The first thing is a formal evaluation for celiac disease, which currently involves blood tests and a small intestinal biopsy. If the evaluation is positive, then a gluten-free diet is necessary. If it's negative, it's best to try a healthier diet with more fruits, vegetables, whole grains and beans while avoiding processed junk. In the past, a gluten-free diet had many benefits over the traditional American diet because it required increasing fruit and vegetable intake--so no wonder people felt better eating gluten-free: no more unhealthy bread products, no more fast food restaurants. Now, there is just as much gluten-free junk out there.

If a healthy diet doesn't help, then the next step is to try ruling out other causes of chronic gastrointestinal distress. In a study of 84 people who claim gluten causes them adverse reactions (they're referred to in the literature as"PWAWGs," People Who Avoid Wheat and/or Gluten), highlighted in my video, How to Diagnose Gluten Intolerance, about a third didn't appear to have gluten sensitivity at all. Instead, they either had an overgrowth of bacteria in their small intestine, were fructose or lactose intolerant, or had a neuromuscular disorder like gastroparesis or pelvic floor dysfunction. Only if those are also ruled out, would I suggest people suffering from chronic suspicious symptoms try a gluten-free diet. If symptoms improve, stick with it and maybe re-challenge with gluten periodically.

Unlike the treatment for celiac disease, a gluten-free diet for gluten sensitivity is ideal not only to prevent serious complications from an autoimmune reaction, but to resolve symptoms and try to improve a patient's quality of life. However, a gluten-free diet itself can also reduce quality of life, so it's a matter of trying to continually strike the balance. For example, gluten-free foods can be expensive, averaging about triple the cost. Most people would benefit from buying an extra bunch of kale or blueberries instead.

No current data suggests that that general population should maintain a gluten-free lifestyle, but for those with celiac disease, a wheat allergy, or a sensitivity diagnosis, gluten-free diets can be a lifesaver.

For more on gluten, check out Is Gluten Sensitivity Real? and Gluten-Free Diets: Separating the Wheat from the Chat.

Some food strategies that may help with irritable bowel symptoms are covered in a few of my previous videos, such as Kiwifruit for Irritable Bowel Syndrome and Cayenne Pepper for Irritable Bowel Syndrome and Chronic Indigestion.

In health,

Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

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How a Gluten-Free Diet Can Be Harmful

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Until only a few years ago, almost the whole of the scientific world maintained that the wheat protein gluten would provoke negative effects only in people with rare conditions such as celiac disease or wheat allergies. But by the early part of 2013, it was largely becoming accepted that some non-celiac patients could suffer from gluten or wheat sensitivity. Indeed, a consensus panel of experts now officially recognizes three gluten-related conditions, wheat allergy, celiac disease and gluten sensitivity.

What percentage of the population should avoid wheat? About 1 in a 1,000 may have a wheat allergy, and nearly 1 in a 100 may have celiac disease. Celiac disease appears to be on the rise, though there's still less than about a 1 in 10,000 chance an American will be diagnosed with celiac in a given year. Our best estimate for wheat sensitivity is in the same general range as celiac, slightly higher than 1 percent. That's still potentially millions of people who may have been suffering for years who could have been cured by simple dietary means, yet who were unrecognized and unaided by the medical profession.

Although gluten sensitivity continues to gain medical credibility, we still don't know how it works. We don't know how much gluten can be tolerated, if it's reversible or not, or what the long-term complications might be of not sticking to a gluten-free diet. Considering the lack of knowledge, people with gluten sensitivity should consider reintroducing gluten back into their diet every year to see if it's still causing problems.

The reason health professionals don't want to see people on gluten-free diets unless absolutely necessary is that, for the 98 percent of people that don't have gluten issues, whole grains--including the gluten grains wheat, barley and rye--are health promoting, linked to reduced risk of coronary heart disease, cancer, diabetes, obesity and other chronic diseases.

Because some people have a peanut allergy doesn't mean everyone should avoid peanuts. There is no evidence to suggest that following a gluten-free diet has any significant benefits in the general population. Indeed, there is some evidence to suggest that a gluten-free diet may adversely affect gut health in those without celiac disease, gluten sensitivity, or wheat allergy. A study out of Spain, highlighted in my video, Gluten-Free Diets: Separating the Wheat from the Chat, found that a month on a gluten-free diet may hurt our gut flora and immune function, potentially setting those on gluten-free diets up for an overgrowth of harmful bacteria in their intestines. Why? Because the very components wheat sensitive people have problems with, like FODMAP and fructans, may act as prebiotics and feed our good bacteria.

Gluten, itself, may also boost immune function. After less than a week on added gluten protein, subjects experienced significantly increased natural killer cell activity, which could be expected to improve our body's ability to fight cancer and viral infections. Another study found that high gluten bread improved triglyceride levels better than regular gluten bread.

Ironically, one of the greatest threats gluten-free diets pose may be the gluten itself. Self-prescription of gluten withdrawal may undermine our ability to pick up celiac disease, the much more serious form of gluten intolerance. The way we diagnose celiac is by looking for the inflammation caused by gluten in celiac sufferers, but if they haven't been eating a lot of gluten, we might miss the disease. Hence, rather than being on a gluten-free diet, we want celiac suspects to be on a gluten-loaded diet. We're talking 4-6 slices of gluten packed bread every day for at least a month so we can definitively diagnose the disease.

Why does it matter to get a formal diagnosis if you're already on a gluten-free diet? Well, it's a genetic disease, so you'll know to test the family. But most importantly, many people on gluten-free diets are not actually on gluten-free diets. Even 20 parts per million can be toxic to someone with celiac. Many on "gluten-free diets" inadvertently eat gluten. Sometimes gluten-free products are contaminated, so even foods labeled "gluten-free" may still not be safe for celiac sufferers.

As editorialized in the Lancet, the irony of many celiac patients not knowing their diagnosis, while millions of non-sufferers banish gluten from their lives, can be considered a public health farce.


Though the medical profession now recognizes wheat sensitivity as a discrete entity, it's still not clear if it's actually the gluten to which people are reacting. For a review of the controversy, see Is Gluten Sensitivity Real?

In How to Diagnose Gluten Intolerance, I go step by step how someone may want to proceed who suspects they might be sensitive to gluten-containing grains.

More on the benefits of whole grains in general in Whole Grains May Work As Well As Drugs and Alzheimer's Disease: Grain Brain or Meathead?

More on keeping our gut flora happy in videos such as Prebiotics: Tending Our Inner Garden and How to Change Your Enterotype.

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

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Gluten Sensitivity Put to the Test

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In 1980, researchers in England reported a series of women with no evidence of celiac disease (the autoimmune disorder associated with gluten intolerance), who nevertheless resolved their chronic diarrhea on a gluten-free diet. The medical profession was skeptical at the time that non-celiac gluten sensitivity existed, and even 30 years later, such patients were commonly referred to psychiatrists. Psychological testing of such patients, however, found no evidence that they were suffering from any kind of psychosomatic hysteria.

The medical profession has a history of dismissing diseases as all in people's heads--post-traumatic stress disorder, ulcerative colitis, migraines, ulcers, asthma, Parkinson's disease, and multiple sclerosis. Despite resistance from the prevailing medical community at the time, these health problems have subsequently been confirmed to be credible physiologically-based disorders rather than psychologically-based confabulations.

On the flipside, the internet is rife with unsubstantiated claims about gluten free diets, which has spilled over into the popular press to make gluten the diet villain du jour, with claims like "17 million Americans are gluten sensitive." However, it must be remembered that the gluten-free food industry is a big business. When literally billions are at stake, it's hard to trust anybody. As always, it's best to stick to the science.

What sort of evidence do we have for the existence of a condition presumed to be so widespread? Not much. The evidence base for such claims has been unfortunately very thin because we haven't had randomized controlled trials demonstrating that the entity even exists. The gold-standard for confirming non-celiac gluten sensitivity requires a gluten-free diet, followed by a double-blind, randomized, placebo-controlled food challenge. For example, give people a muffin and don't tell them if it's gluten-free or gluten-filled--to control for placebo effects--and see what happens. The reason this is necessary is because when you actually do this, a number of quote-unquote "gluten-sensitive" patients don't react at all to disguised gluten and instead react to the gluten-free placebo.

We never had that level of evidence until 2011, when a double-blind, randomized placebo-controlled trial was published, which tested to see if patients complaining of irritable bowel symptoms who claimed they felt better on a gluten free diet--despite not having celiac disease--actually could tell if they were given gluten containing bread and muffins or gluten-free bread and muffins.

Subjects started out gluten-free and symptom-free for two weeks and then were challenged with the bread and muffins. In my video, Is Gluten Sensitivity Real?, you can see what happened to the 15 patients who got the placebo, meaning they started out on a gluten-free diet and continued on a gluten-free diet. They got worse. Just the thought that they may be eating something that was bad for them made them feel crampy and bloated. This is what's called the nocebo effect. The placebo effect is when you give someone something useless and they feel better; the nocebo effect is when you give someone something harmless and they feel worse. On the other hand, the small group that got the actual gluten, felt even worse still. The researchers concluded that non-celiac gluten intolerance may therefore indeed exist.

It was a small study, though, and even though the researchers claimed the gluten-free bread and muffins were indistinguishable, maybe at some level the patients could tell which was which. So in 2012, researchers in Italy took 920 patients that had been diagnosed with non-celiac gluten sensitivity and put them to the test with a double-blinded wheat challenge by giving them capsules filled with wheat flour or filled with placebo powder. More than two-thirds failed the test, such as getting worse on the placebo or better on the wheat. But of those that passed, there was a clear benefit to staying on the wheat-free diet. The researchers concluded that their findings confirmed the existence of a non-celiac wheat sensitivity. Note I said "wheat sensitivity," not "gluten sensitivity."

Gluten itself may not be causing gut symptoms at all. Most people with wheat sensitivity have a variety of other food sensitivities. Two thirds are sensitive to cow's milk protein, and many are sensitive to eggs. If we put people on a diet low in common triggers of irritable bowel symptoms, and then challenge them with gluten, there's no effect. We find the same increase in symptoms with high gluten, low gluten, or no gluten diets, calling into question the very existence of non-celiac gluten sensitivity.

Interestingly, despite being informed that avoiding gluten didn't seem to do a thing for their gut symptoms, many participants opted to continue following a gluten-free diet as they subjectively described "feeling better." So researchers wondered if avoiding gluten might improve the mood of those with wheat sensitivity. Indeed, short-term exposure to gluten appeared to induce feelings of depression in these patients. Whether non-celiac gluten sensitivity is a disease of the mind or the gut, it is no longer a condition that can be dismissed.


More than 10,000 articles have been published on gluten in medical journals--intimidating even for me! Combined with the multi-billion dollar financial interests on both sides, it makes for a difficult task. But I think I did it! This is the first of a 3-part series summarizing the best available science on gluten. Also check out: Gluten-Free Diets: Separating the Wheat from the Chat and How to Diagnose Gluten Intolerance.

Why this apparent increase in food sensitivities in recent decades? It could be because of pollutant exposure (see Alkylphenol Endocrine Disruptors and Allergies and Dietary Sources of Alkylphenol Endocrine Disruptors).

What can we do about preventing so-called atopic diseases (like allergies, asthma, and eczema)? See my videos Preventing Allergies in Adulthood and Preventing Allergies in Childhood. The weirdest example of an emerging food sensitivity may be the tick-bite related meat allergy story I review in Alpha Gal and the Lone Star Tick and Tick Bites, Meat Allergies, and Chronic Urticaria.

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

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A Simple Yet Neglected Cure for Childhood Constipation

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Back in the 1950s, it was suggested that some cases of constipation among children might be due to the consumption of cow's milk. But it wasn't until 40 years later that it was finally put to the test. We used to think that most chronic constipation in infants and young children was all in their head--they were "anal retentive"--or had some intestinal disorder, but a group of Italian researchers studied 27 consecutive infants who showed up in their pediatric gastroenterology clinic with chronic "idiopathic constipation" (meaning they had no idea what was causing it), and tried removing cow's milk protein from their diet.

Within three days on a cow's milk protein-free diet, 21 out of the 27 children were cured. There were clinical relapsea during two subsequent cow milk challenges, meaning when they tried giving the children back some cow's milk, the constipation reappeared within 24 to 48 hours. The subjects came back after a month and stayed cured, and their eczema and wheezing went away, too! The researchers concluded that many cases of chronic constipation in young children--more than three quarters it seemed, may be due to an underlying cow's milk protein allergy.

Chronic constipation is a common problem in children, for which fiber and laxatives are prescribed. If those don't work, several laxatives at progressively higher dosages can be used, and that still may not work. Five years later, a considerable number of kids are still suffering. In fact, chronic constipation may even extend into adulthood. To cure the disease in just a few days by eliminating cow's milk was a real breakthrough.

But it was an open trial, meaning not blinded or placebo-controlled. We didn't have such a trial until a landmark study was published in the New England Journal of Medicine--a double-blind, crossover study, comparing cow's milk and soy milk. The study enrolled 65 kids suffering from chronic constipation, all previously treated unsuccessfully with laxatives; 49 had anal fissures and inflammation and swelling. The researchers gave them either cow's milk or soy milk for two weeks and then switched it around.

In two thirds of the children, constipation resolved while they were receiving soy milk, and the anal fissures and pain were cured. None of the children receiving cow's milk had a positive response. In the 44 responders, the relation with cow's milk protein hypersensitivity was confirmed in all cases by a double-blind challenge with cow's milk. All those lesions, including the most severe anal fissures, disappeared on a cow's milk-free diet, yet reappeared within days after the reintroduction of cow's milk back into their diets.

This may explain why children drinking more than a cup of milk a day may have eight times the odds of developing anal fissures. Cutting out milk may help cure anal fissures in adults, too. Cow's milk may also be a major contributor to recurrent diaper rash as well.

Why does removing cow's milk treat these conditions? Studies that have looked at biopsy tissue samples in patients with chronic constipation because of cow's milk protein hypersensitivity have found signs of rectal inflammation, suggesting that cow's milk protein was inducing an inflammatory response.

Studies from around the world have subsequently confirmed these findings, curing up to 80 percent of kids' constipation by switching to soy milk or rice milk. A common problem with the studies, though, is when they switched kids from cow's milk to non-dairy milk, the kids could still have been eating other dairy products. That is, they didn't control the background diet...until recently. A 2013 study (highlighted in my video, Childhood Constipation and Cow's Milk, got constipated kids off all dairy products and 100 percent were cured, compared with 68 percent in the New England Journal study.

Isn't this amazing? I just kept thinking, "why didn't I learn this in medical school?" Is the dairy lobby so persuasive that a cheap, simple, safe, life-changing intervention like this remains buried?

Until now!

If you appreciate learning what your child's pediatrician probably never did, please consider making a donation to the 501c3 nonprofit charity that keeps this website going. I don't make a penny off the site, but it does require substantial server and logistics costs.

Make sure to check out tomorrow's video: Treating Infant Colic by Changing Mom's Diet.

Avoiding dairy may be important for infant health too. Watch my 3-part video series:

Then the effects on adolescents and beyond:

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

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The #1 Dietary Risk Factor is Not Eating Enough Fruit

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The Global Burden of Disease Study published in 2012, is the most comprehensive and systematic analysis of causes of death undertaken to date, involving nearly 500 researchers from more than 300 institutions in 50 countries, and starting with almost 100,000 data sources. What did the researchers find? Here in the U.S., they determined that our biggest killer was our diet. Number 1 on their list of the most important dietary risks was not eating enough fruit, responsible for an estimated 4.9 million deaths a year around the world.

According to the Union of Concerned Scientists: "If Americans ate just one more serving of fruits or vegetables per day, this would save more than 30,000 lives and $5 billion in medical costs each year." One antidote for individuals is easy, painless, and even pleasurable: exploit the multiple nutritional and protective benefits of fruits and vegetables.

One way plants protect us may be their antiplatelet effects. Platelets are what trigger the blood clots that cause heart attacks and most strokes. And beyond their obvious function in blood clotting, platelets are now considered to play a pivotal inflammatory role in the hardening of the arteries in the first place, and in allergies, rheumatoid arthritis, and even cancer.

Normally, under healthy conditions, platelets circulate in a quiescent, inactive state. But once they become activated, they can emerge as culprits in inflammation. Platelets transport a vast amount of inflammatory chemicals, and upon activation they release these chemicals, which can recruit the inflammatory cells that form the pus pockets within our arterial walls that can eventually burst and kill us.

This involvement of platelet activation in atherosclerosis development is well established. We've long recognized the platelets' role in the final stages; however, a growing body of data indicates that platelets may also play an important role in the initiation and propagation of atherosclerosis in the first place. How can we prevent the excessive activation of platelets? It's generally recognized that platelet hyper-reactivity is associated with high levels of cholesterol circulating in the blood; so we can cut down on foods that have trans fats, saturated fats, and dietary cholesterol.

We can also eat more fruits and vegetables. For example, different varieties of strawberries have shown a significant antiplatelet effect in a petri dish and in people. How did researchers figure it out? In my video, Inhibiting Platelet Aggregation with Berries, you can see a platelet in a resting state, packed with little round granule grenades of inflammatory chemicals, which fuse together and are released when the platelet gets activated. Because resting and activated platelets look so different, we can just take blood from people and count how many are resting and how many are activated before and after people eat more than a pint of strawberries every day for a month. From just adding strawberries to people's diets, there's a small but significant drop in the percentage of activated platelets circulating throughout their bodies.

Other berries had a similar effect, even at a more modest two servings a day. Drinking orange or grapefruit juice doesn't seem to help, but purple grape juice successfully reduces platelet activity on the same order that aspirin does.

Studies have shown that daily aspirin can reduce heart attacks and strokes; however, aspirin can also cause severe gastrointestinal disturbances and bleeding problems, and so should not be used for the primary prevention of heart attacks and stroke as the benefits don't clearly outweigh the serious risks. It's nice to have safe, side-effect free alternatives.


One of the ways plants help keep platelets in their place may actually be their aspirin content! See Aspirin Levels in Plant Foods. Why would a plant make a human drug? It's so cool, check out Appropriating Plant Defenses.

Is the Standard American Diet really so bad that we could save 100,000 people by just getting up to minimum fruit and veggie recommendations? Even cynics might be surprised: Nation's Diet in Crisis. Even more plants may cut deaths even more, though. See One in a Thousand: Ending the Heart Disease Epidemic.

For more on lowering cholesterol see my video Trans Fat, Saturated Fat, and Cholesterol: Tolerable Upper Intake of Zero. And it's never too early to start eating healthier. Check out: Heart Disease Starts in Childhood. Heart disease may be a choice. See: Cavities and Coronaries: Our Choice.

Berries are the healthiest fruits, shown to maintain our brain power (How to Slow Brain Aging By Two Years) and improve our immune function (Boosting Natural Killer Cell Activity). That's one of the reasons we want to eat Antioxidant Rich Foods With Every Meal.

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

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Hives from Tick Bite-Induced Meat Allergies

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In a previous video Alpha Gal and the Lone Star Tick, I started talking about a tick bite-induced meat allergy, called Alpha-Gal, that is unlike any other food allergy we know. The most interesting feature of the reactions may be that first symptoms can occur hours after eating meat. Normally, an allergic reaction to a bee sting, for example, happens within minutes. With this meat allergy, we could have a piece of bacon for breakfast and our throat wouldn't start closing off until the afternoon. Because the cause and effect are temporarily separated, we often blame other factors, such as what we ate for lunch, or we just call it "spontaneous" or "idiopathic" anaphylaxis, which is just doctor-speak for "we have no idea what the cause is."

The delay likely occurs because the alpha-gal is probably absorbed along with the fat in meat, given that the allergic reaction occurring four to five hours after meat ingestion corresponds to the peak absorption time of fatty acids from the intestinal tract.

What makes the allergy even more difficult to diagnose is that the majority of victims experience only occasional overt reactions, despite regular meat consumption. Fattier meats, like pork rinds, may provoke episodes more consistently and severely, but still don't trigger a reaction every time.

Tick bite-induced meat allergy is on the rise. Ten years ago we didn't even know this thing existed, but now in tick-ridden states as many as 20% of the population have these anti-meat allergic antibodies (See Tick Bites, Meat Allergies, and Chronic Urticaria). And more and more people are coming in affected, though probably no more than 10% who test positive go on to experience hives or serious allergic reaction to meat.

We're also seeing it more and more in kids. Researchers in Virginia have found that it is not uncommon, though identification of the allergy may not be straightforward. Unlike in adults, who frequently present with systemic reactions, the majority of children with this syndrome present with just skin manifestations, such as hives. However, this doesn't mean it's not serious. In fact, nearly half the kids ended up in the ER, and about 1 in 12 needed to be hospitalized.

Up to a quarter of the population breaks out in hives at some time in their lives, but some children can be affected for weeks or months. It can be triggered by infections, foods, drugs, parasites, or be autoimmune, but in a large subset of cases we don't know what the trigger is, and so, call it chronic "idiopathic" urticaria. It's a common thing pediatricians see. The only cure is avoiding and eliminating whatever is triggering it, but in three quarters of cases we have no clue.

We now know that many children who had been diagnosed with mysterious hives or allergic reactions and may have been specifically told that the reactions were not a result of a food allergy, may have actually been suffering from anti-gal meat allergies. The serious nature of the reactions and the rising frequency of allergic swelling and hives across all age groups underscore the importance of identifying what's going on, and physicians should keep this new diagnosis in mind.

Allergies to meat might be more common than previously thought, as much as 2% of the population (which would mean millions of people). But to put this in context, Americans are much more likely to suffer an anaphylactic reaction due to seafood, tick bite or not, no matter where they live. A national survey of emergency rooms found shellfish was by far the most frequently implicated food, and unlike many other allergies, kids don't tend to outgrow fish and shellfish allergies.

Some fish allergies are actually allergies not to the fish, but to worms in the fish, like anisakis, which are found particularly in cod, anchovies, and squid. Exposure to these parasites in fish, living or dead, is a widespread problem. In fact, we can even have an allergic reaction to the parasitic fish worm when we eat chickens that were fed on fishmeal. This is one of the ways someone who's allergic to fish could get triggered by chicken.

Because of these worms, researchers recommend that people stop eating seafood and sushi altogether, because besides inducing allergenic reactions, the worms may cause a leaky gut syndrome, which often is unrecognized and can predispose someone to other, more important pathologies than just being itchy all over.

I previously covered anisakis in Allergenic Fish Worms and other allergenic parasite reactions in Chronic Headaches and Pork Tapeworms.

The worms might not the only thing increasing allergies in fish. See:

I also did a 4-part series on allergies in general if anyone's interested:

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my videos for free by clicking here and watch my full 2012 - 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.

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How a Tick Bite Can Lead to Food Allergies

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In the beginning, Aristotle defined two forms of life on planet Earth: plants and animals. Two thousand years later, the light microscope was invented and we discovered tiny, single-celled organisms like amoebas. Then, the electron microscope was invented and we discovered bacteria. Finally, in 1969, biologists recognized fungi as a separate category, and we've had at least five kingdoms of life ever since.

In my video, Higher Quality May Mean Higher Risk, I talk about the potential downsides of consuming proteins from within our own kingdom, such as the impact our fellow animal proteins can have on boosting our liver's production of a cancer-promoting hormone called IGF-1.

In Eating Outside Our Kingdom, I talked about other potential advantages of preferably dipping into the plant and mushroom kingdoms for dinner, not only from a food safety perspective (we're more likely to get infected by animal pathogens than Dutch Elm Disease), but because of the potential for cross-reactivity between animal and human proteins. Our immune system is more likely to get confused between a chicken leg and our own legs than it is with a banana, so there may be less potential to trigger an autoimmune reaction, like degenerative brain diseases or inflammatory arthritis (See Diet & Rheumatoid Arthritis). In attacking some foreign animal meat protein, some of our own similarly composed tissues may get caught in the crossfire.

It's not just proteins. If you remember the Neu5Gc story (see Inflammatory Meat Molecule Neu5GC), sialic acid in other animals may cause inflammation in our arteries (see Nonhuman Molecules Lining Our Arteries) and help breast tumors and other human cancers to grow (see How Tumors Use Meat to Grow: Xeno-Autoantibodies). Now a new twist has been added to the story.

The reason Neu5Gc triggers inflammation is because humans lost the ability to make it two million years ago, and so when our body is exposed to it through animal products, it's treated as a foreign molecule, causing inflammation. But there's also another oligosaccharide called alpha-gal that humans, chimps, and apes lost the ability to make 20 million years ago, but is still made by a variety of animals, including many animals we eat.

Anti-gal antibodies may be involved in a number of detrimental processes that may result in allergic, autoimmune, and autoimmune-like diseases, such as auto-immune thyroid disorders. We see higher levels of anti-gal antibodies in Crohn's disease victims. These antibodies even react against about half of human breast tumors, and we can find them in atherosclerotic plaques in people's necks. However, those are all mostly speculative risks. We do know that alpha-gal is a major obstacle to transplanting pig organs into people, like kidneys, because our bodies reject alpha-gal as foreign. In fact, alpha-gal is thought to be the major target for human anti-pig antibodies.

It's interesting that if we look at those that abstain from pork for whatever reason, they have fewer swine-specific immune cells in their bloodstream. Researchers speculate that oral intake of pork could ferry swine molecules into the bloodstream via gut-infiltrating lymphocytes to prime the immune response. So we can have an allergic reaction to eating pig kidneys too, but such severe meat allergies were considered rare, until an unusual report surfaced. First described in 2009, the report included details on 24 cases of meat allergies triggered by tick bites.

Within a year, it was obvious that the cases should be counted in hundreds rather than dozens. By 2012, there were thousands of cases across a large area of the southern and eastern U.S., and new cases are now popping up in several countries around the world.

The culprit, the lone star tick, so-called because females have a white spot on their back, are famous for causing Masters' disease, a disease similar to Lyme syndrome, also known as STARI (southern tick associated rash illness). But thanks to the lone star tick steadily expanding its range (even as far as Long Island, NY), it's not necessarily just so Southern any more.

What is the relevance of tick bites to the production of allergy-causing anti-meat antibodies to alpha-gal? Good question. What we know is that if you get bitten by one of these ticks, you can develop an allergy to meat (See Alpha Gal and the Lone Star Tick). This appears to be the first example of a response to an external parasite giving rise to an important form of food allergy. We don't know the exact mechanism, but it may be because there's something in the tick saliva that's cross-reacting with alpha-gal, or because the tick is injecting you with animal allergens from its last meal.

What role may these tick-bite induced allergies play in the development of chronic hives and other allergic skin reactions in children? See Tick Bites, Meat Allergies, and Chronic Urticaria.

Here's some videos unearthing the IGF-1 story:

Neu5Gc is what opened up this whole can of worms:

I wonder if alpha gal is playing a role in the improvements in arthritis and Crohn's on plant-based diets: Dietary Treatment of Crohn's Disease and Diet & Rheumatoid Arthritis.

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my videos for free by clicking here and watch my full 2012 - 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: USGS Bee Inventory and Monitoring Lab / Flickr

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Do Walnuts Really Improve Artery Function?

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Good news for nut lovers: Eating at least one serving of walnuts per week may drop our chances of a cardiovascular-related death by 50%. However, walnut consumption may only drop our cholesterol levels about 5%. How could we get a 50% drop in cardiac mortality from just a 5% drop in cholesterol? Walnuts must have some other heart-protecting benefits besides lowering cholesterol.

The ability of blood vessels to relax and open normally is considered an excellent barometer of underlying vascular health. For example, even after controlling for other risk factors, 80% of those with better than average arterial function survived cardiac event-free over the years, whereas 80% of those with below average dilation didn't. So what effect do nuts have? A 2011 review in the journal Nutrition, Metabolism, and Cardiovascular Diseases found five clinical trials analyzing the effect of nut consumption on arterial function, and all three studies on walnuts showed an improvement in endothelial function measured in the arm. The study on pistachios also found a positive effect, but the study on hazelnuts was a wash.

A subsequent study on hazelnuts, however, did find a significant improvement in arterial function, so the data for hazelnuts is mixed, whereas two subsequent walnut studies (highlighted in my video, Walnuts and Artery Function) confirmed walnuts' benefits. Therefore, eight studies to date have investigated the effect of nuts on brachial artery function; seven out of eight showed a significant improvement in arterial function, one showed a negligible effect, and none found nuts made things worse.

Half the studies, though, used the added nuts to replace foods in the diet known to have a negative effect on endothelial function. For example, in one study, walnuts replaced meat and dairy, which have been shown to be detrimental, so no wonder arterial function got better. When we do a study like that, we can't tell if the benefits are because of the addition of the good stuff or the removal of the bad. In three of the other studies, nuts replaced olive oil, which tends to lead to a worsening of endothelial function. Therefore, in these four studies, the beneficial effects of the walnuts may have been exaggerated.

However, the other four studies just added nuts as a snack or with a meal, without replacing any specific foods, and found that nuts significantly improved arterial functioning. Given their association with longevity (see Nuts May Help Prevent Death), I encourage everyone to eat an ounce of nuts a day (unless of course you're allergic). Only about 1% of people report nut allergies, but still, that eliminates nut consumption for millions of Americans.

What else can nuts do? See, for example:

Don't nuts make us fat, though? You may be surprised--see Nuts and Obesity: The Weight of Evidence.

Which type of walnut is better? Black Versus English Walnuts.

What about the phytates in nuts--do we need to soak or toast them? See:

-Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, and From Table to Able.

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Treating Asthma With Plants vs. Pills

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In my video Treating Asthma With Fruits and Vegetables, I highlighted a landmark study on manipulating antioxidant intake in asthma. The study found that just a few extra fruits and vegetables a day can powerfully reduce asthma exacerbation rates. If the antioxidants in the plants are ameliorating asthma, then why can't we take antioxidant pills instead? Because antioxidant pills don't appear to work.

Studies using antioxidant supplements on respiratory or allergic diseases have mostly shown no beneficial effects. This discrepancy between data relating to fruit and vegetable intake compared with those using antioxidant supplements may indicate the importance of the whole food, rather than individual components. For example, in the Harvard Nurse's Health Study, women who got the most vitamin E from their diet appeared to be at half the risk for asthma, (which may help explain why nut consumption is associated with significantly lower rates of wheezing), but vitamin E supplements did not appear to help.

Men who eat a lot of apples appear to have superior lung function, as do kids who eat fresh fruit every day, as measured by FEV1 (basically how much air you can forcibly blow out in one second). The more fruit, salad, and green vegetables kids ate, the greater their lung function appeared.

Researchers are "cautious about concluding which nutrient might be responsible." There's vitamin C in fruits, salads, and green vegetables, but there are lots of other antioxidants, such as "vitamin P," a term used to describe polyphenol phytonutrients found in grapes, flax seeds, beans, berries, broccoli, apples, citrus, herbs, tea, and soy. Polyphenol phytonutrients can directly bind to allergenic proteins and render them hypoallergenic, allowing them to slip under our body's radar. If this first line of defense fails, polyphenols can also inhibit the activation of the allergic response and prevent the ensuing inflammation, and so may not only work for prevention, but for treatment as well.

Most of the available evidence is weak, though, in terms of using supplements containing isolated phytonutrients to treat allergic diseases. We could just give people fruits and vegetables to eat, but then we couldn't perform a double-blind study to see if they work better than placebo. Some researchers decided to use pills containing plant food extracts. Plant extracts are kind of a middle ground. They are better than isolated plant chemicals, but are not as complete as whole foods. Still, since we can put whole foods in a capsule, we can compare the extracts to fake sugar pills that look and feel the same to see if they have an effect.

The first trial involved giving people extracts of apple skins. I've talked about the Japan's big cedar allergy problem before (See Alkylphenol Endocrine Disruptors and Allergies), so apple extract pills were given every day for a few months starting right before pollen season started. The results were pretty disappointing. They found maybe a little less sneezing, but the extract didn't seem to help their stuffy noses or itchy eyes.

What about a tomato extract? A randomized, double-blind, placebo-controlled eight-week trial was performed on perennial allergic rhinitis, this time not for seasonal pollen, but for year-round allergies to things like dust-mites. There are lots of drugs out there, but you may have to take them every day year-round, so how about some tomato pills instead? After oral administration of tomato extract for eight weeks, there was a significant improvement of total nasal symptom scores, combined sneezing, runny nose and nasal obstruction, with no apparent adverse effects.

Would whole tomatoes work even better? If only researchers would design an experiment directly comparing phytonutrient supplements to actual fruits and vegetables head-to-head against asthma, but such a study had never been done... until now. The same amazing study, highlighted in my video, Treating Asthma with Plants vs. Supplements?, that compared the seven-fruit-and-vegetables-a-day diet to the three-fruit-and-vegetables-a-day diet, after completion of its first phase, commenced a parallel, randomized, controlled supplementation trial with capsules of tomato extract, which boosted the power of five tomatoes in one little pill, and the study subjects were given three pills a day.

Who did better, the group that ate seven servings of actual fruits and vegetables a day, or the group that ate three servings a day but also took 15 supposed serving equivalents in pill form? The pills didn't help at all. Improvements in lung function and asthma control were evident only after increased fruit and vegetable intake, which suggests that whole-food interventions are most effective. Both the supplements and increased fruit and vegetable intake were effective methods for increasing carotenoid concentrations in the bloodstream, but who cares? Clinical improvements--getting better from disease--were evident only as a result of an increase in plant, not pill, consumption. The results provide further evidence that whole-food approaches should be used to achieve maximum efficacy of antioxidant interventions.

And if this is what a few more plants can do, what might a whole diet composed of plants accomplish? See Treating Asthma and Eczema with Plant-Based Diets.

I also dealt with preventing asthma in the first place: Preventing Asthma With Fruits and Vegetables.

The theme of whole foods being more efficacious than supplements seems to come up over and over again. See for example:

More on "vitamin P" in How to Slow Brain Aging by Two Years.

The anti-inflammatory effects of nuts may explain the Harvard Nurse's Health Study finding: Fighting Inflammation in a Nut Shell.

-Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, and From Table to Able.

Image Credit: Mike Mozart / Flickr

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