Kitchen 101: Nutrition in Produce
Eat the rainbow! You’ve likely heard this tossed about by foodies, nutritionists, and diehard vegetable fans. But what does it mean? It is really just a fancy way to say you should eat a balanced diet, and that you should buy every color fruit or vegetable available at your local market. Why?
Fruits and vegetables get their colors (and other unique characteristics like smell, texture, etc) from various phytochemicals. Each phytochemical has its own set nutrients. Since the phytochemicals that make something red are different from the phytochemicals that make something green, the nutrients, and health benfits, of those two plants are going to be different. Simply said, you can’t get the same vitamins and minerals from red fruits that you can get from green vegetables. This is why you should eat the rainbow.
Unlike our vision, which we can sum up with a tidy 7 colors and the ROYGBIV (red, orange, yellow, green, blue, indigo, and violet) slogan, the amount of phytochemicals, vitamins, minerals, and nutritional elements and metals that exist is staggering. It would almost be silly to categorize produce solely on color, so, that’s what I’ve done here! There are many vitamins, nutrients and health benefits that can be found in a majority of one color of produce, so it’s worth looking at anyway.
First, before we jump into the types of nutrients we’ll find in different color produce, let’s look at the factors that affect the nutritional value of fruits and vegetables, and more importantly, what we can do to ensure we’re getting the most nutrient bang for our buck.
There are numerous factors than can affect the nutrition of a particular fruit or vegetable, the most impactful often being cooking method and time. I’ve included general guidelines for the amount of cooking a particular fruit or vegetable can sustain before it turns into an unappetizing, nutrient-void puddle in the graphic. As a general rule though, the less cooking time the better, but this isn’t always true, especially for vegetables like broccoli, or fruit like tomatoes.
Cooked versus Raw: As for the whole raw vegetable myth, raw vegans will go as far as telling you that by cooking vegetables or fruits at all, you are removing most of the nutrients and making them useless. This just isn’t true. In fact, many nutrients found in produce only become readily absorbed by the body after they’ve been broken down in the cooking process (cooking softens and breaks down cell walls making the nutrients more readily accessible).
Also, some vitamins and minerals have a natural tendency to dissipate quicker than others. Vitamin C is lost to processing, cooking, and reheating much quicker than others such as zinc.
If you don’t know the 15 basic cooking methods, visit my previous Kitchen 101 post on Cooking Methods.
Cooking time is not the only factor that can suck nutrients from produce. The cooking method used also has an effect. Some of the most common methods used for cooking vegetables (boiling, simmering, poaching, and blanching) are also the most likely to leech the most nutrients out of the fruit or vegetable. Notice a trend in these methods? They’re all wet cooking methods, meaning they use water, particularly submersion in water. Steaming however, another wet cooking method, is not as harmful to your nutrient intake. If you want the healthiest form of cooking, you should stick to steaming. I on the other hand shall stick to frying my vegetables in lots and lots of butter – because dairy is healthy, right?
The fresher the vegetable or fruit is, the more nutrients it will have. The longer produce sits out, the more likely it has lost a lot of its healthy vitamins. In fact, many nutritionists will suggest eating fruits and vegetables within a week of picking.
Fresh versus Frozen: So, fresh vegetables in the produce section are more nutritious than frozen, right? Nope, at least not always. The time between picking and freezing is likely shorter than the time between picking and getting the produce to the store, and eventually into your mouth.
Specific colors and phytochemicals aside, some nutritionists suggest opting for the most vibrant fruit or vegetables, as the more saturated or bright produce look, the more likely it is to contain more phytochemicals and thus more nutrients.
Eat it All
Eat the skin! Eat everything! People freakout when they find out I eat the skin on kiwi but just about every part of produce we can buy is edible (there are obvious exceptions so please don’t eat a rhubarb leaf or apple seeds and then come yell at me – both are poisonous if you didn’t know). So stop peeling your potatoes, stop cutting the skin off an apple, and, well, don’t eat the shell of a melon though – there’s so much fiber in the rind that I wouldn’t want to be there when it’s time to, umm, expel it.
ROYGBIV (Technically ROWGB)
While the spectrum of visible colors for humans is ROYGBIV, for the sake of nutrients found in produce, we can shorten that a bit by combining orange and yellow, and blue, indigo, and violet. We do need to add a tan and white section though too. These five groups cover just about every vitamin and nutrient out there, at least those you can get from produce.
Red fruits and vegetables typically get their color from lycopene and anythocyanins. While these flavanoids have been linked to powerful cancer-fighting properties and are lauded for their antioxidant properties, red produce is most notable for it’s typically high levels of vitamin A, vitamin C, Manganese, and Fiber.
Together you get fruits and vegetables that are good for memory, lung function, joints, and fighting various cancers including prostate cancer. Red produce is also good for lowering LDL cholesterol, lowering blood pressure, and fighting free radicals.
Notable Red Produce: Take note of pomegranates with their high levels of various B vitamins, rhubarb with its high concentrations Vitamin K and Calcium, and beets for its high folate and B9 count.
Orange and Yellow
Chances are you already know what contributes the yellow and orange pigment to these fruits and vegetables. That’s right; it’s beta-carotene (a form of vitamin A). Orange and yellow fruits and vegetables are also colored with carotenoids. Because these fruits and vegetables are just a pigment away from their red cousins, they contain a similar vitamin and mineral profile. This group is high in Vitamin A and C, just like their red buddies. They also are typically abundant in fiber. The yellow ones typically contain more vitamin C but less vitamin A than the orange ones.
So what does this mean for us? Orange and yellow produce is great for our immune system, heart health, fighting aging, vision, and skin health. Just like red produce, a well-balanced diet of orange and yellow fruits and vegetables will help lower LDL cholesterol and blood pressure, and can help fight those pesky free radicals.
You’ll also notice significant levels of manganese, potassium, and various B vitamins in this group.
Notable Orange and Yellow Produce: The star here could definitely be the banana which is high in B6, potassium and manganese plus a bunch of other vitamins and minerals. Don’t forget sweet potatoes and corn which are both high in various B vitamins. Corn is also rich in magnesium and starch.
White and Tan
So, where do white, tan, and brown produce get their color, or lack of color? The plant pigment Anthoxanthin is the workhorse here though beta-glucans, lignans and other complicated, long-named chemical compounds play their part too. Just because this group is void of color, it doesn’t mean they are lacking in vitamins and nutrients. In fact, these fruits and vegetables are stars when it comes to the immune system as they are filled with anti-bacterial, anti-fungal, and anti-viral properties. You’ll also find vitamin C, vitamin K, folate, and fiber in this group.
These seemingly colorless fruits and vegetables are great at reducing the risk of various cancers, balancing hormone levels, and most importantly improving and aiding our immune system. If you’ve got a cold, skip the chicken soup and go straight to an onion and garlic broth.
Notable White and Tan Produce: Soy beans. These miracle plants are packed with vitamin B6, choline, iron, magnesium, phosphorus, potassium and, sodium. Not only that but they’re high in protein too. It’s little surprise you can find just about anything and everything made from soy these days.
The most celebrated of the colors has to be green, after all how often have you heard your mother demand you, “eat your greens!”
And that’s for good reason. Green vegetables and fruits mostly get their color from the Biology 101 star, chlorophyll, which incidentally is powerful in fighting cell damage that can lead to cancers). This green group is filled with vitamin K, vitamin C, numerous B vitamins, just about every nutritional metal, and various minerals including, calcium, and potassium. Green produce, especially those leafy greens, are chocked full of fiber too.
The fruits and vegetables in this group are great at aiding digestion, improving the immune system, and are beneficial for our vision, bones, and teeth. You can also lower your LDL cholesterol and blood pressure with a healthy helping of daily greens. Studies also show that greens can help fight diabetes and promote heart health. Now you know why your mother has advocated a green diet all these years.
Notable Green Produce: Let’s start with the avocado which is high in vitamin B2, B3, B5, B6, and B9, vitamin E, and potassium. Edamame (soy beans) are also high in just about every B vitamin, and they also contain iron, magnesium, manganese, phosphorus, potassium, and zinc. Asparagus, Brussels Spouts, and Peas are all high in vitamin B1, Iron, and numerous other elements.
Blue and Purple
Blue and purple comes from anthocyancins (like you find in red produce), which are powerful antioxidants. They also contain other phytochemincals and flavanoids such as lutein, zeaxanthin, resveratrol, ellagic acid, and quercentin, all adding to their powerful antioxidant and cancer-fighting properties. You’ll also find fiber, vitamin C, vitamin K, and manganese in significant quantities in blue fruits and vegetables.
In addition to fighting cancer, the blue group is great for improving memory and brain functions, fighting inflammation, improving the immune system, aiding in digestion, fighting aging, and heart health. They are also reported to be anti-carcinogens, which means they can help slow, stop, or even reverse cancerous cell growth.
Notable Blue and Purple Produce: Figs with their high levels of calcium, iron, magnesium, phosphorus, and potassium, may be there stars here but you shouldn’t overlook the plethora of berry varities (both those you can find in the store and those you can only find out in the wild), which carry significant levels of vitamin K, manganese, vitamin E, folic acid and more.
Eating the Rainbow
This is why proponents of healthy eating will always tell you to buy and eat the rainbow. Each group contains vital nutrients that other groups do not. And while some colors shine with an overabundance of vitamins, minerals, and phytochemicals, you’ll be starving your body of a number of necessary nutrients if you favor one color over the others.
What about supplements: Synthesized vitamin supplements can be very different from their naturally derived counterparts.While some studies show taking daily vitamin supplements can help, just as many studies show that they do little or nothing, and can even do more harm. I am a proponent of eating naturally, so I will always advise buying produce (in addition to grains, cereals, and meats) to get your daily value of vitamins over taking supplements.
This is just half of the produce story. Knowing what produce is in season will help you buy the most nutritious fruits and vegetables available. Check out my Kitchen 101: Produce Calendars for a complete look at the seasonal availability of various vegetables, fruits and herbs.
Check out the other Kitchen 101 posts.