Oh, the controversy over green smoothies and juices! Are they great for you...or not so great? Of course, if you're choosing between a green juice and a doughnut, there shouldn't even be a moment's discussion. But beyond that, the web is studded with debates and arguments for and against green juices and smoothies.
As I write this, I'm drinking a cold-pressed juice of chard, kale, celery, cucumber, lemon, and spinach, without added fruit. Am I causing harm or helping my health?
Let's dive into the science. In the last few years, a new system has been identified in our bodies that supports heart health: inorganic nitrates. Leafy greens and some other vegetables, like beets, are rich in them. When we swallow these nitrate-rich vegetables, they are rapidly absorbed in our GI tracts and appear in our bloodstream. They can be converted by the way of enzymes into nitric oxide (NO).
Let's all give a big cheer for NO. This miracle gas is made in the lining of our 50,000 miles of arteries (endothelium). When our arteries produce a lot of NO, our arteries relax, our blood pressure is normal, our blood is less likely to clot, and our arteries resist making plaque. There's another reason to be grateful for NO. When we want to have sex, it's NO that causes blood vessels to dilate and engorge the parts that need to grow. In other words: When you want to say yes to sex, say NO.
So when we eat leafy greens and drink our green juices and smoothies, the dietary nitrates power our blood vessels and improve the overall quality of our lives.
Then what's the controversy? There's an argument that to get the effects of dietary nitrates, our food needs to come in contact with bacteria on our tongue that convert the nitrates to make NO in our arteries. If you quickly gulp your green juices or smoothies past your tongue, you may not permit time for the bacteria to munch on the dietary nitrates.
But there is a secret, second pathway that you should know about. When our blood level of nitrates rise after eating or drinking plant-based nitrate-rich foods, the nitrates enter our salivary gland and are concentrated in our saliva. Our saliva may have nitrate concentrations 10 times that of our blood. How convenient! The green drink we swallowed 45 minutes ago may be secreted right on to our tongue to enjoy the bacteria-nitrate interaction. So if the bacteria don't get your dietary nitrates the first time down, this "entero-salivary" recirculation makes sure they get them the second time around. Is that not amazing?
So, fear not the green juices and smoothies. In fact, enjoy them! (But leave the fruit content low or absent.)
Here's one of my favorite detoxing green smoothies that will make your arteries say Hallelujah.
- 1 cup green tea, chilled (or 1 teaspoon matcha green tea in water)
- 1 cup loosely packed cilantro
- 1 cup loosely packed organic baby kale (or another baby green)
- 1 cup organic cucumber
- 1 cup pineapple
- juice of 1 lemon
- 1 tablespoon fresh ginger, grated
- ½ avocado
Place ingredients into a blender and puree until smooth.
Joel Kahn, MD, FAAC