With our fast-paced and busy lifestyles, a green smoothie for breakfast has become popular and commonplace. It’s quick, easy, and conveniently has several of your daily servings of green vegetables in one cup. Loading up our smoothies with superfoods makes this a no-brainer for the health-conscious, busy professional or parent. However, most folks don’t know that there is actually value in traditionally preparing many foods. Science is showing us that blending handfuls of raw spinach or kale on a regular basis may not actually be in your best health interest.
While cooking does can diminish some nutrients like water-soluble vitamin Bs and C, there are other nutrients that become more bioavailable after cooking. The beta carotenes (which the body converts into vitamin A) found in spinach and kale are only increased after cooking, such as steaming or sauteeing.
Another concern is for those with a history or tendency to form kidney stones. Kidney stones are typically made up of calcium and oxalates which bind together to form crystals or calcium oxalate stones. Many green vegetables are naturally high in oxalates. However, cooking the vegetables will lower the oxalates. Some people simply don’t excrete oxalates as well as others lending towards a higher propensity to form stones.
Certain vegetables are considered goitrogenic, or goitrogens, meaning they can disrupt the production of thyroid hormone interrupting the uptake of iodine, eventually leading to the formation of a goiter. Cruciferous vegetables, such as broccoli, kale, brussels sprouts, collard greens and cabbage tend to be goitrogenic. Yet, cooking these vegetables lowers their goitrogenic properties. While small amounts of raw goitrogenic foods are not a problem, you see more benefits from cooking these vegetables. While it’s not too common to see a goiter in today’s world, it is better to avoid raw cruciferous if there is a thyroid imbalance.
Finally, from a Chinese medicine perspective, too many raw foods can be hard on the digestive system and dampen the digestive fire. It is recommended for someone who tends to have more cold type digestive symptoms to not eat too many cold, raw foods, especially in the form of a smoothie where we tend to drink it down rather than chew. Chewing activates digestive enzymes in the mouth to begin the process of digestion.
If your goal is to get in more greens at each meal, try a more traditional breakfast of congee with cooked greens or eggs with sautéed greens. You might find you feel more satiated and satisfied.