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:

Raisins and Dental Health

Raisins have a long-standing reputation as a food that promotes dental caries (cavities),” based on decades-old studies on rats that ranked raisins up there with cupcakes as among the most cavity-promoting foods. To this day, you’ll see dental authorities advise against eating dried fruit, like raisins. As I discuss in my video Do Raisins Cause Cavities?, more recent evidence—from studies done on actual people—“casts some doubt on the role of raisins with regards to tooth decay.”

The formation of cavities depends on three factors: acid, adherence (the stickiness of food to teeth), and the bacteria that make up the dental plaque. If you have kids swish some sugar water in their mouth, within five minutes, the pH of the plaque on their teeth plummets as the bacteria convert the sugar to acid. A commercial raisin bran cereal was practically just as bad. Bran flakes alone, without the raisins, weren’t as bad, however. Is that because the raisins in raisin bran cereal are crusted with sugar, though, or because of the raisins themselves? Well, raisins didn’t lead to much acid at all, and the big surprise was that if you combined the non-sugar-coated raisins with the bran flakes to create a kind of experimental raisin bran cereal, the raisins seemed to help prevent some of the acid the bran flakes were causing.

Although raisins are about 70 percent pure sugar, they caused less acid to be produced, and don’t actually appear to adhere to our teeth. Wait. Raisins do stick to our teeth, don’t they? Twenty-one foods were put to the test, and there was actually no relationship between food retention and how sticky the foods appeared to be. Bits of cookies, crackers, and potato chips actually stuck to the teeth the longest, whereas foods you’d think would stick, like caramels and raisins, disappeared within minutes. Fresh fruit like apples and bananas disappeared from the mouth almost immediately.

Phytonutrients in grapes appear to actually prevent the adherence of bacteria and prevent plaque formation, so much so that grape pomace, the by-product of wine making, is being investigated as a cavity-preventing food additive. Or, you could just drink the wine. Non-alcoholic wine inhibits the growth of the primary cavity-causing bacteria, though raisins would probably be a more appropriate snack for kids.

There’s a new test available to measure the cavity-causing activity of plaque bacteria. A pilot study was performed to see if the risk for cavities increases, decreases, or remains the same after eating raisins. They took 156 folks, swabbed their teeth, waited for the readings to get up over 1,500, which indicates high cavity-causing activity, and had half eat a little box of raisins and the other half eat nothing. In the eat-nothing control group, they started out at around 6,100 and, 15 minutes later, were still up at 6,100. The raisin group started around 5,950, but, after raisin consumption, their cavity risk score dropped down to 3,350. Although that’s a big reduction, note the score was still higher than the 1,500 cutoff, indicating they were still at risk—but the risk went down after eating raisins, not up. So, while raisins traditionally have been thought to promote tooth decay, current research suggests that raisins may not contribute to cavities after all—or at least not any more than other foods.


For more on raisins, see:

What about dried fruit in general? Check out:

To learn more about oral health, 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:

The Best Diet for the Inflammation of Aging

One of the most consequences of aging is a decline in immune function, illustrated by vulnerability to dying from the flu and poor response to vaccinations. But, about 20 years ago, a paper was published showing that the immune cells of 80-year-olds produced significantly more pro-inflammatory signals. As I discuss in my video, How to Counter the Inflammation of Aging, this suggests the worst of both worlds—a decline in the part of the immune system that fights specific infections and an aggravation of nonspecific overreactions that can lead to inflammation. This has since been formalized in a concept referred to as a chronic low-grade inflammation that we now know is typical of aging, which may be responsible for the decline and onset of disease in the elderly.

So, what can we do about it? Inflamm-aging appears to be a major consequence of growing old. Can it be prevented or cured? “The key to successful aging and longevity is to decrease chronic inflammation without compromising an acute response when exposed to pathogens.” How do we do that? Nutrition. What we eat is “probably the most powerful and pliable tool that we have to attain a chronic and systemic modulation of aging process…”

In the first systematic review ever published of the associations between dietary patterns and biomarkers of inflammation, the dietary patterns associated with inflammation were almost all meat-based or so-called Western diet patterns. In contrast, vegetable- and fruit-based, or “healthy,” patterns tended to be inversely associated with inflammation. In general, the more plant-based, the less inflammation.

The reason meat is associated with inflammation may be because of both the animal protein and the animal fat. In the first interventional study that separately evaluated the effects of vegetable and animal protein on inflammatory status, researchers found that “a higher intake of animal origin protein—specifically meat—is associated with higher plasma levels of inflammatory markers in obese adults…”

The reason obesity is associated with increased risk of many cancers may be because of obesity-associated inflammation. Obesity-driven inflammation may stimulate prostaglandin-mediated estrogen biosynthesis in breast tissues. What does that mean? The inflammation may activate the enzyme that allows breast tumors to make their own estrogen via an inflammatory compound called prostaglandin. If you measure the level of prostaglandins in women’s urine, it correlates with breast cancer risk. And what can cause high levels of this inflammatory compound? Smoking, a high-saturated fat diet, and obesity. Why does eating saturated fat lead to prostaglandin production? Because prostaglandins are made from arachidonic acid, and arachidonic acid is a major ingredient in animal fats. To put it another way, animal fats contain arachidonic acid, and our body produces inflammatory compounds, like prostaglandins, with arachidonic acid. Inflammatory compounds can then go on to stimulate breast cancer growth and may also play a role in colon cancer, lung cancer, and head and neck cancer.

In contrast, whole plant foods have anti-inflammatory effects, though some plants are better than others. Folks made to eat five-a-day of high-antioxidant fruits and vegetables, like berries and greens, had a significantly better impact on reducing systemic inflammation and liver dysfunction compared those eating five-a-day of the more common low-antioxidant fruits and veggies, like bananas and lettuce.


You can learn more about arachidonic acid in Chicken, Eggs, and Inflammation and Plant-Based Diets for Improved Mood and Productivity.

More on battling inflammation in:

And more on healthy aging in:

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: