We Have Specific Fruit and Vegetable Receptors

According to a recent survey, the number of Americans adults who say they are eating ‘pretty much whatever they want’ is at an all-time high,” which unfortunately includes “too few fruits and vegetables,” as well as “too little variety.” Half of all fruit servings are taken up by just six foods: orange juice, bananas, apple juice, apples, grapes, and watermelons. Only five foods—iceberg lettuce, frozen potatoes, fresh potatoes, potato chips, and canned tomatoes—make up half of all vegetable servings. We’re not only eating too few fruits and veggies. We’re also missing out on the healthiest fruits, which are berries, and the healthiest vegetables, which are dark green leafies. The fruit and vegetable palette for our palate is sadly lacking.

Why does dietary diversity matter? As I discuss in my video Specific Receptors for Specific Fruits and Vegetables, different foods may affect different problems. Cabbage, cauliflower, broccoli, and Brussels sprouts are associated with lower risk of colon cancer in the middle and right side of our body, whereas risk of colon cancer further down on the left side of our body appears to be better lowered by carrots, pumpkins, and apples. So, “different F/V [fruits and vegetables] may confer different risks for cancer” of different parts of even the same organ.

Variety is the spice of life—and may prolong it. “Independent from quantity of consumption, variety in fruit and vegetable consumption may decrease lung cancer risk,” meaning if two people eat the same number of fruits and vegetables, the one eating a greater variety may be at lower risk.

It’s not just cancer risk. In a study of thousands of men and women, a greater quantity of vegetables and a greater variety may independently be beneficial for reducing the risk of type 2 diabetes. Even after removing the effects of quantity, “each different additional two item per week increase in variety of F&V [fruit and vegetable] intake was associated with an 8% reduction in the incidence of T2D [type 2 diabetes].” Why? Well, it “may be attributable to individual or combined effects of the many different bioactive phytochemicals contained in F&V. Thus, consumption of a wide variety of F&V will increase the likelihood of consuming” more of them.

“All the vegetables may offer protection…against chronic diseases,” but “[e]ach vegetable group contains a unique combination and amount of these [phytonutrients], which distinguishes them from other groups and vegetables within their own group.” Indeed, because “each vegetable contains a unique combination of phytonutriceuticals (vitamins, minerals, dietary fiber and phytochemicals), a great diversity of vegetables should be eaten…to get all the health benefits.”

Does it matter, though, if we get alpha-carotene or beta-carotene? Isn’t an antioxidant an antioxidant? No. “It has been shown that phytochemicals bind to specific receptors and proteins” in our bodies. For example, our body appears to have a green tea receptor—that is, a receptor for EGCG, which is a key component of green tea. There are binding proteins for the phytonutrients in grapes, onions, and capers. In my video The Broccoli Receptor: Our First Line of Defense, I talk about the broccoli receptor, for instance. Recently, a cell surface receptor was identified for a nutrient concentrated in apple peels. Importantly, these target proteins are considered indispensable for these plants foods to do what they do, but they can only do it if we actually eat them.

Just like it’s better to eat a whole orange than simply take a vitamin C pill, because, otherwise, we’d miss out on all the other wonderful things in oranges that aren’t in the pill, by just eating an apple, we’re also missing out on all the wonderful things in oranges. When it comes to the unique phytonutrient profile of each fruit and vegetable, it truly is like comparing apples to oranges.


This is one of the reasons I developed my Daily Dozen checklist of foods to incorporate into one’s routine. Download the free iPhone and Android apps, and be sure to watch my video Dr. Greger’s Daily Dozen Checklist.

I discuss how produce variety—not just quality and quantity—may be important in Apples and Oranges: Dietary Diversity and Garden Variety Anti-Inflammation, so I hope you’ll check them out. You can also learn more about why combining certain foods together may be more beneficial than eating them separately in Food Synergy.

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:

How to Maximize Nutrient Absorption

Unhealthy lifestyle behaviors associated with an increased risk of premature death include smoking, excessive alcohol drinking, and not eating enough greens. The best way to get your greens is in whichever way you’ll eat the most of them, and one way to sneak extra greens into your daily diet is with whole-food smoothies, “a potent blend of good nutrition” in a quick, portable, delicious form.  

The Mayo Clinic offers a basic green smoothie recipe, combining the healthiest of fruits and the healthiest of vegetables, berries and dark green leafies, respectively. It calls for 2 ounces of baby spinach, which is about a cup and a half. Consider adding in some curly parsley, another mild beginner green to start with. Surprisingly, the sweetness of the fruit masks any bitterness from the greens such that the pickiest of children love these smoothies, as do adults who otherwise would not consume dark green leafy vegetables—or even fruit—for breakfast. Indeed, the average teen may only get about 1/20th of a serving of fruit otherwise—and Froot Loops don’t count. 

Offering smoothies can have a dramatic effect on fruit consumption for “students who do not want to take time peeling or chewing fruits.” (Who doesn’t have time to chew a fruit?!) The milkshake-y texture of smoothies may not only boost the quantity of fruit and vegetable consumption, but also the quality. 

Carotenoid phytonutrients, like beta-carotene and lycopene, can exist as microscopic crystals trapped inside the cell walls of fruits and vegetables. They’re only released when the cells are disrupted, which is why we have to chew really well. We either have to chew better or choose plants that are easier to chew. For example, while tomatoes have more beta-carotene than watermelon does, watermelon’s beta-carotene is more bioaccessible because its cell walls are wimpy compared with the smaller and tougher cell walls of other fruits and vegetables. To maximize nutrient release, food particle size would ideally be reduced to smaller than the width of the individual plant cells, but you can’t do that with chewing. Most vegetable particles end up greater than two millimeters when you chew them, whereas if we broke open all the cells, we could release much more nutrition, as you can see in my video, Are Green Smoothies Good for You?. The particle size distribution from chewing is about what you’d get blending in a food processor for about five seconds or one of those high-speed blenders for maybe half a second. Just 40 seconds in a blender can break down spinach to a subcellular level. 

Why does that matter? Let’s look at folate, the B vitamin in greens that is especially important for women of child-bearing age. Feed people a cup of spinach a day for three weeks and their folate goes up compared to control. What happens if you eat finely chopped spinach instead of whole leaves? You end up with more than twice as much in your bloodstream and the same absorption-boosting effect with lutein, the green nutrient so important for our eyesight.

It’s not what you eat—it’s what you absorb.  

The boost for lutein was only 14%, so a few extra bites of the whole leafy greens would have given you just as much. Some other nutrients, such as vitamin C, aren’t affected by pre-chopping at all. This is also less of an issue with cooked vegetables. If you boil carrots for three minutes, regular chewing can release about ten times more beta-carotene bioaccessibility than eating them raw, but not as much as blended. Intense cooking, like boiling for 25 minutes, so damages the cell walls so even gulping down large particles can result in significant absorption. But, blending may double carotenoid availability, explaining why we may be able to absorb three times the alpha- and beta-carotene from pureed cooked carrots compared to mashed cooked carrots. So, blending vegetables—raw or cooked—into soups, sauces, or smoothies can maximize nutrient absorption. Whether you went to the store and bought it, or toiled in your garden to grow it, you might as well take full advantage of it.  


Check out my other videos that touch on smoothies:

For other tips on getting children of all ages to eat healthier, see Tricks to Get Kids to Eat Healthier at Home and Tricks to Get Adults to Eat Healthier.

Finally, learn more about the effect of cooking on nutrient loss and absorption from these videos: Best Cooking Method, Raw Food Nutrient Absorption, and Sometimes the Enzyme Myth Is True.

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:

What to Eat to Cure High Blood Pressure

High blood pressure ranks as the number-one risk factor for death and disability in the world. In my video, How to Prevent High Blood Pressure with Diet, I showed how a plant-based diet may prevent high blood pressure. But what do we do if we already have it? That’s the topic of How to Treat High Blood Pressure with Diet

The American Heart Association (AHA), the American College of Cardiology (ACC, and the Centers for Disease Control and Prevention (CDC) recommend lifestyle modification as the first-line treatment. If that doesn’t work, patients may be prescribed a thiazide diuretic (commonly known as a water pill) before getting even more meds until their blood pressure is forced down. Commonly, people will end up on three drugs, though researchers are experimenting with four at a time. Some patients even end up on five different meds.

What’s wrong with skipping the lifestyle modification step and jumping straight to the drugs? Because drugs don’t treat the underlying cause of high blood pressure yet can cause side effects. Less than half of patients stick with even the first-line drugs, perhaps due to such adverse effects as erectile dysfunction, fatigue, and muscle cramps.

What are the recommended lifestyle changes? The AHA, ACC, and CDC recommend controlling one’s weight, salt, and alcohol intake, engaging in regular exercise, and adopting a DASH eating plan.

The DASH diet has been described as a lactovegetarian diet, but it’s not. It emphasizes fruits, vegetables, and low-fat dairy, but only a reduction in meat consumption. Why not even more plant-based? We’ve known for decades that animal products are significantly associated with blood pressure. In fact, if we take vegetarians and give them meat (and pay them enough to eat it!), we can watch their blood pressures go right up.

I’ve talked about the benefits to getting blood pressure down as low as 110 over 70. But who can get that low? Populations centering their diets around whole plant foods. Rural Chinese have been recorded with blood pressures averaging around 110 over 70 their whole lives. They eat plant-based day-to-day, with meat only eaten on special occasions.

How do we know it’s the plant-based nature of their diets that was so protective, though?

Because in the Western world, as the American Heart Association has pointed out, the only folks getting down that low on average were those eating strictly plant-based diets, coming in at about 110 over 65.

So were the creators of the DASH diet just not aware of this landmark research done by Harvard’s Frank Sacks? No, they were aware. The Chair of the Design Committee that came up with the DASH diet was Dr. Sacks himself. In fact, the DASH diet was explicitly designed with the number-one goal of capturing the blood pressure-lowering benefits of a vegetarian diet, yet including enough animal products to make it “palatable” to the general public.

You can see what they were thinking. Just like drugs never work—unless you actually take them. Diets never work—unless you actually eat them. So what’s the point of telling people to eat strictly plant-based if few people will do it? So by soft-peddling the truth and coming up with some kind of compromise diet, the on a population scale maybe you’d do more. Ok, but tell that to the thousand U.S. families a day that lose a loved one to high blood pressure. Maybe it’s time to start telling the American public the truth.

Sacks himself found that the more dairy the lactovegetarians ate, the higher their blood pressures. But they had to make the diet acceptable. Research has since shown that it’s the added plant foods—not the changes in oil, sweets, or dairy—that appears to the critical component of the DASH diet. So why not eat a diet composed entirely of plant foods?

A recent meta-analysis showed vegetarian diets are good, but strictly plant-based diets may be better. In general, vegetarian diets provide protection against cardiovascular diseases, some cancers, and even death. But completely plant-based diets seem to offer additional protection against obesity, hypertension, type-2 diabetes, and heart disease mortality. Based on a study of more than 89,000 people, those eating meat-free diets appear to cut their risk of high blood pressure in half. But those eating meat-free, egg-free, and dairy-free may have 75% lower risk.

What if we’re already eating a whole food, plant-based diet, no processed foods, no table salt, yet still not hitting 110 over 70? Here are some foods recently found to offer additional protection: Just a few tablespoons of ground flaxseeds a day was 2 to 3 times more potent than instituting an aerobic endurance exercise program and induced one of the most powerful, antihypertensive effects ever achieved by a diet-related intervention. Watermelon also appears to be extraordinary, but you’d have to eat around 2 pounds a day. Sounds like my kind of medicine, but it’s hard to get year-round (at least in my neck of the woods). Red wine may help, but only if the alcohol has been taken out. Raw vegetables or cooked? The answer is both, though raw may work better. Beans, split peas, chickpeas, and lentils may also help a bit.

Kiwifruits don’t seem to work at all, even though the study was funded by a kiwifruit company. Maybe they should have taken direction from the California Raisin Marketing Board, which came out with a study showing raisins can reduce blood pressure, but only, apparently, compared to fudge cookies, Cheez-Its, and Chips Ahoy.


The DASH diet is one of the best studied, and it consistently ranks as US News & World Report’s #1 diet. It’s one of the few diets that medical students are taught about in medical school. I was so fascinated to learn of its origins as a compromise between practicality and efficacy.

I’ve talked about the patronizing attitude many doctors have that patients can’t handle the truth in:

What would hearing the truth from your physician sound like? See Fully Consensual Heart Disease Treatment and The Actual Benefit of Diet vs. Drugs.

For more on what plants can do for high blood pressure, see:

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: