If you find yourself in a conversation about “Vitamin P,” there are two likely explanations…
One: you’re among unusually candid psychiatrists (“Vitamin P” is industry slang for Paxil or Prozac). Two: you’ve stumbled into a time machine set to 1950. That decade marked the last time scientists (or really anyone) used “Vitamin P” to describe flavonoids, a chemical compound found in most fruits and veggies.
Today, whether you call it “Vitamin P” or flavonoids, it’s the latest way to explain why something we know is good (eating fruits and vegetables) actually is good.
What are flavonoids and what foods are they in?
Most likely, the “p” refers to “phytonutrients,” a fancier way to say “plant chemicals.” It rolls off the tongue far easier than any of these subtypes of Vitamin P:
- Anthocyanidins. Found in red, blue, and purple berries, grapes and… yup, red wine.
- Anthoxanthins. Found in white, colorless, creamy or yellow vegetables like onions or cauliflower.
- Flavanols. The chameleon of flavonoids, found in the cruciferous vegetables that stink up the office microwave (brussels sprouts, cabbage, broccoli), but also apples, berries, and tea.
- Flavones. Typically in herbs, light greens, and garnishes, such as parsley and celery.
- Flavonones. The citrus flavonoid, abundant in lemons, grapefruit and oranges.
- Flavans. Dwell in black tea and chocolate (sweet!) but are removed due to their bitterness (not so sweet!).
- Isoflavones. Highly concentrated in soy products and other legumes.
Pro tip: Eat a variety of produce. Flavonoids are abundant in the same foods you typically see recommended by any nutrition professional. But the amount and bioavailability (whether your body can actually use it) differs between sources, so it’s best to err on the side of variety.
You can appreciate flavonoids just by browsing the produce section. Notice how certain flavonoids tend to appear in fruits and vegetables of the same color? It’s kind of their job — they’re responsible for produce’s rich, vivid pigment — with the exception of anthoxanthins, the “neutral” flavonoid.
Flavonoids aren’t to be confused with carotenoids, the phytonutrients that provide the bright orange, red, and yellow hues of, say, carrots.
Eat too many carotenoid-containing foods and your skin might actually turn orange. Really. But if you go on a blueberry binge, the resulting dose of anthocyanidin won’t make you look like Violet Beauregarde.
Oh, but the wonderful things Vitamin P can do — supposedly. Numerous studies have shown flavonoids to have antioxidant and anti-inflammatory properties.
Despite their bad rap, oxidation and inflammation are natural processes, and sometimes even helpful. Inflammation can be a byproduct of normal activities ranging from breathing to weightlifting. (Muscles that are ready to rebuild are inflamed.)
But oxidation and inflammation are things you want to prevent if you can. And that’s one reason to reap the curative properties and cardiovascular health benefits of flavonoids.
In fact, tally up all of the studies done on flavonoids and you might believe they can prevent cancer, improve diabetes control, and increase erectile function. (Heck, they even make plants attractive to pollinators!)
What works for plants works for us, right? So why aren’t we eating handfuls of blueberry-infused cauliflower right this moment? Well, we don’t eat just the flavonoids. Every nutrient, vitamin, mineral, and spice interacts with each other inside the food we eat and within our bodies.
The milk in your cocoa might interfere with flavonoid absorption; carb-rich foods might increase absorption of flavonoids, but some flavonoids might interfere with carbohydrate absorption. Since our bodies use carbs as a primary source of energy, that’s usually bad.
But reduced carbohydrate (i.e. sugar) uptake is good for people with type II diabetes. In fact, the flavonoids found in cocoa have the most promise for those with diabetes. Confused yet?
Cardiovascular health and vitamin P
Fact is, like so many other “Next Big Things,” flavonoid studies exhibit the fatal flaw in many studies: correlation doesn’t equal causation. This is most true of the cardiovascular disease studies that have thrust vitamin P into the spotlight.
Yes, participants who had higher flavonoid intake showed fewer biomarkers of inflammation in the short-term. But people who consume high amounts of flavonoids are likely to already have a high-quality diet.
So how can we assume it’s just the flavonoids reducing inflammation? And are people with a high-quality diet more likely to be nonsmokers and exercisers? We know those are also contributors to cardiovascular health.
Also, most of these studies are prospective, meaning that they’re done before anyone develops cardiovascular issues.
Even the strong association of flavanol-rich cocoa and reduced hypertension didn’t account for the similarity of participants in the study group. These are what are known as “confounding factors,” or “alternate explanations for the thing that happened.”
Cancer and vitamin P
Flavonoids probably aren’t the elusive Cure for Cancer. They’ve been found to successfully fight various forms of chemically-induced cancers in animal studies. But there’s no compelling evidence that this applies to human organs.
Other studies suggest that flavonoids could be used to lower risk of breast and prostate cancer, due to their interactions with sex hormones.
Then there are the studies that warn of potential drug contraindication with flavonoid-containing produce, particularly the notorious grapefruit. Even the risk of flavonoid-on-flavonoid interaction has yet to be determined.
Even if you do have a diet rich in fruits and vegetables, that doesn’t guarantee a wealth of flavonoids in your system. Storing your onions outside of the refrigerator? That’ll lose you some flavonoids.
Think of the fruits and vegetables that you need to peel or cook to enjoy. This will also result in flavonoid loss. Also take environmental factors like soil and ripening into account.
For those who don’t have much fruit and veggie intake, there are numerous flavonoid supplements on the market.
The good news: there have been no adverse effects associated with high intake of flavonoids. The bad news: Taking flavonoid supplements aren’t the same as obtaining flavoniods naturally from fruits and veggies, since foods have other vitamins and nutrients that help with the absorption of flavonoids.
The lowdown on supplements
When shopping for flavonoids, it’s important to choose high-quality supplements that are third-party tested for purity.
Although supplements are monitored by the FDA, they aren’t as strictly regulated as pharmaceuticals, meaning that supplements aren’t always safe and effective. This is why it’s essential to consult your doctor before starting a new supplement and always to choose trusted brands.
Contrast this to the well-established incidence of complications of other vitamin overdosing: kidney stones (vitamin C), nerve damage (vitamin B), and dizziness, nausea, or even death (vitamin A).
The bad news: the relative lack of risk is due to their low bioavailability (maybe we’re just peeing them out after they get quickly metabolized).
This might explain why flavonoids are incredible antioxidants in a test tube while much less so in our bodies, since they’re found in much lesser quantities than other antioxidants (such as vitamin C). And studies cast doubt on whether flavonoids found in supplements can truly be harmless.
It’s hard to go wrong eating foods rich in vitamin P — you likely haven’t met a dietary professional who’d recommend avoiding the kinds of fruits and vegetables that contain flavonoids. If you do, well… maybe you’ve stumbled back into that 1950’s time machine.
There’s little doubt that the benefits of consuming flavonoids outweigh the risks. The only question is the extent of those benefits.
Yes, flavonoids are correlated with lowered risk of cancer, cardiovascular disease, and even ringing ears. But a $45 bottle of cocoa flavonols might have nothing on the proverbial apple a day.