Raw or cooked? How to eat your leafy green vegetables (Hint: It’s not necessarily raw)

After writing my column on juicing a couple of weeks ago, I received an email from a reader asking why, if raw kale is purported to be so healthy, was I against drinking it.

Another reader had a question about the word “blenderizing.”  In fact, she wrote, “do you mean making juice in a blender?”

I’ll take the second question first. By “blenderizing” I mean everything you put into the machine is what you consume.  You can use a regular blender, or a high-end machine like a Vitamix or NutriBullet.  Since your ‘smoothie’ contains all of the fiber of the fruits and vegetables, it has the advantage of providing fullness.  You may add nuts, chia or flax seeds, yogurt or milk or milk alternatives such as almond or soymilk to boost the protein and nutrition.

But since the machine is doing all the mastication (chewing), you miss out on the benefits imparted by chewing, including bypassing salivary enzymes, which are essential to good digestion and absorption of certain nutrients.  Drinking pre-chewed food increases the likelihood of consuming more calories than you would if you ate (and chewed) the bunch of ingredients.

Roasted vegetables, olive oil recipe.

Juicing is when you use a special machine that will separate the liquid part of the fruit or vegetable from the pulp (fiber), and you discard the fiber.  Eliminating the fiber produces a liquid source of concentrated calories.  Yes, it’s a concentrated source of vitamins too, but dumping fructose (the natural sugar present in fruits and vegetables) into your stomach isn’t helpful for energy and blood glucose control.  Most health experts advocate for consuming whole (unprocessed) fruits and vegetables.

Regarding drinking kale. A cup of chopped raw kale contains 9% of your daily calcium, 206% of daily vitamin A, and more than 684% of your daily vitamin K.  But how much kale are you putting into that blender? Typically, more than one cup of chopped kale.  Probably a lot more.

Vitamin K is the clotting vitamin, and one cup has more than six times the recommended amount for adults. If you’re taking a blood-thinning medication, or aspirin to reduce inflammation, an overload of kale can interfere with your medications.

Kale, spinach, chard, collards and beet greens are rich in oxalic acid, which binds with calcium and other minerals like magnesium and iron to be excreted from the body.  If you’re at risk for kidney stones, you’re advised to minimize oxalates and excessive vitamin C, so again, drinking these vegetables in concentrated forms is not advisable.

Brassica or cruciferous vegetables like kale, cabbage, broccoli, cauliflower and Swiss chard are high in isothiocynates, which eaten raw in large amounts could be linked to hypothyroidism.  But health expert emphasize that eaten in usual amounts, raw or cooked, these vegetables are healthful. What is a “usual amount”?  Read more below.

Raw and Cooked: Eat Your Fruits & Veggies

A daily dose of leafy greens and other vegetables is critical for maintaining good health, and that goes for fruit too.  Whole foods are best, cooked and raw.

Many foods are naturally more enjoyable, safer and even more nutritious when cooked

Topping the list of foods that are more enjoyable, safer and even more nutritious when cooked are the obvious — meats, fish and eggs. Humans have lengthened our lifespan partly because we’ve learned how to make foods safer with heat.

Some plant foods are healthier when eaten raw: definitely include raw produce in your diet, and some plant foods are healthier when cooked. Let’s look at some raw and some cooked nutrient profiles.

Raw beets are better. Beets lose about 25% of their folate when cooked — so try beets raw, shredded in a salad with carrots and radishes.

Raw garlic’s allicin is a more potent antioxidant when uncooked, but it’s pretty sharp tasting; I prefer it roasted.

Raw cacao’s micronutrients are excellent, but unsweetened, it is bitter! Pair with mango or other sweet fruit.

Raw chia seeds are good sources of soluble fiber, calcium, magnesium, and antioxidants, but they’re a little difficult to get out of your teeth — soak first, or grind.

Proper cooking brings out the flavor, enjoyment, and boosts nutrition in many foods.

Research shows that carrots, spinach, mushrooms, asparagus, cabbage and bell peppers pack more antioxidants when lightly cooked.

Mushrooms: Sauté, grill, or roast mushrooms to release the muscle-building potassium.

Spinach: Lightly steamed or quickly sauté with some olive oil to promote absorption of fat-soluble vitamins A, E, and K. Add some vitamin C by adding lemon juice or vinegar to help you absorb the iron in spinach too.

Broccoli: Heating broccoli deactivates myrosinase, an enzyme in broccoli that helps cleanse the liver of carcinogens, however, the fiber-related components in broccoli do a better job of binding together with bile acids in your digestive tract when they’ve been steamed. When this binding process takes place, it’s easier for bile acids to be excreted, and the result is a lowering of your cholesterol levels. Raw broccoli still has cholesterol-lowering ability — just not as much. I enjoy broccoli both raw and cooked. Read more here.

Tomatoes: Lycopene is the red pigment in tomatoes and other rosy fruits, including guava, papaya and watermelon. It’s a powerful antioxidant that’s linked to a lower risk for cancer and heart attacks. Research shows that turning up the heat on tomatoes enhances lycopene’s potency, transforming it into a more easily absorbable form. The best source of lycopene in the entire store is canned tomato paste.

More is not always better when it comes to vitamins and minerals. Although a blended smoothie can pack a punch of vitamins, minerals, and fiber, it’s best to not overdo on certain leafy greens.  If you enjoy a fresh vegetable/fruit smoothie, combine a variety of ingredients in single-serving amounts to avoid overloading on any nutrients.  Be careful about throwing in the whole fruit, for example, some peels and seeds are absolutely indigestible and are known to be toxic (cherimoya for one). Read more about food safety here.

Serving size

Vegetables: 1 cup of raw leafy vegetables (about the size of a small fist), ½ cup of other vegetables or  ½ cup of vegetable juice.

Fruits: 1 medium fruit (medium is defined as the size of a baseball); ½ cup chopped, cooked or canned fruit; or ½ cup juice.

Your daily needs are dependent on your age, sex, and level of physical activity.  To find your recommended daily and weekly amount from each Vegetable and Fruit subgroup click here and here.

Sources

CNN.com. Health. The healthiest ways to cook veggies and boost nutrition. http://www.cnn.com/2016/05/05/health/healthy-vegetable-cooking/

NutritionData.com. Kale, raw: Nutrition facts & calories.  http://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2461/2

Ohio State University: Research. Turning up the heat on tomatoes boosts absorption of lycopene. http://researchnews.osu.edu/archive/lycoproc.htm

Scientific American. Fact or fiction: raw veggies are healthier than cooked ones. https://www.scientificamerican.com/article/raw-veggies-are-healthier/

The World’s Healthiest Foods. Broccoli: What’s new and beneficial about broccoli. http://www.whfoods.com/genpage.php?tname=foodspice&dbid=9

USDA ChooseMyPlate.gov. https://www.choosemyplate.gov/MyPlate

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