Do you want another reason to add green leafy vegetables into your diet? How does, ‘having a more efficient central nervous system and better visual function’ sound?
Dr. Billy R. Hammond recently gave a seminar to the University of Georgia Foods and Nutrition department, entitled “The influence of the macular carotenoids on the central nervous system.” Dr. Hammond works with carotenoids, which are pigments (color compounds) found in colorful fruits and vegetables.
What do carotenoids do?
Carotenoids are important antioxidant compounds. They can be found in high concentrations in the retina (the part of the central nervous system directly behind the eye) and in the brain. Both the brain and retina use a lot of energy, and because of this, are vulnerable to damage by dangerously reactive forms of oxygen. These reactive forms of oxygen are products created by normal cellular processes. Our bodies handle these destructive forms of oxygen by using antioxidants (such as vitamin E, vitamin C, and carotenoids) to cancel them out. Having carotenoids to work as antioxidants in these active parts of our bodies protects us from damage.
In addition to preventing damage, carotenoids help our central nervous system by improving the communication between nervous system cells (neurons). Because carotenoids improve the communication between neurons, then they, in theory, would make our central nervous system more efficient (or faster). A faster central nervous system could result in improved reaction time. Dr. Hammond has conducted several studies evaluating if carotenoid supplements make the central nervous system faster.
Do carotenoids make our central nervous system more efficient?
Using two types of carotenoids, lutein and zeaxanthin, Dr. Hammond has studied the effects of supplemental carotenoids on vision and cognition in multiple groups of people. In a study of UGA baseball players, a population for which rapid visual processing is very important, the researchers found that lutein and zeaxanthin supplements improved visual processing and speed.
In other studies of both college-age students and adolescents, Dr. Hammond’s research team has found that lutein and zeaxanthin supplementation improved cognitive function and neural activity.
What does this information mean for you?
The standard American diet is very low in fruits and vegetables. When we don’t eat a variety of fruits and vegetables or take a supplement, we don’t get the carotenoids we need for efficient functioning of our central nervous system and vision. I think it is important for findings such as these not to be misinterpreted or blown out of proportion. The findings of Dr. Hammond’s work do not mean that Americans should eat carotenoids to become super smart humans with super hero vision. The findings do indicate that the carotenoids lutein and zeaxanthin play important roles in vision and cognition, and are worth including in your daily diet to support an efficient central nervous system.
You can increase your intake of lutein and zeaxanthin by incorporating leafy greens such as kale, spinach, swiss chard, mustard greens, turnip greens, or collards into your diet.
One of my favorite ways to eat kale is in kale apple salad. Here is a link to a recipe you can try: https://cooking.nytimes.com/recipes/1013732-kale-salad-with-apples-and-cheddar
Enjoy!
Hannah – In high school, I had a friend who hated fruits and vegetables, so he would take Juice Plus as a way to try and make up for not eating as healthy as he knew he should. Of course, a dietary supplement cannot completely replace eating real fruits and vegetables, but the companies who make these products typically market them as the end-all-be-all, magical health pill that will give you every vitamin, mineral, antioxidant, and essential nutrient that you will ever need. Now, as highly educated in food sciences and nutrition as you are, I am confident that you would agree with me when I say that Juice Plus, or any other form of dietary supplement that is meant to serve as a replacement for the real food item, is an imperfect substitute. With this thinking in mind, I was a little curious as to why you make the suggestion to eat more colorful fruits and vegetables should a person want to increase their intake of lutein and zeaxanthin when they could much more easily and conveniently take a lutein and zeaxanthin supplement instead? When I read this post, this is the question that came to mind – why eat all of these fruits and vegetables, some of which I may not enjoy, are too expensive, or am unfamiliar with preparing, when I could much more easily take a supplement instead – especially since using a dietary supplement was the method applied by Dr. Hammond in his research study. Personally, I really like fruits and vegetables and I consciously incorporate them into my diet every day, but I am playing Devil’s advocate here and reading this article from the perspective of the average American who consumes the “standard American diet.” Also, I Googled “carotenoids reaction time” and came across a news article citing Dr. Hammond’s research and providing a couple of brands of supplements which people could take to increase their carotenoid intake – even the media suggests taking a supplement rather than simply eating healthier foods which contain these carotenoids. It seems we are fighting an uphill battle to influence people towards leading lives full of HEAL.
Thank you for your thoughtful comment! I agree with you that a dietary supplement cannot replace eating whole fruits and vegetables. There are two main points I will bring up to support this:
1. An unhealthy diet + a supplement does NOT equate to a healthy diet. If you are eating foods that contain, for example, lutein and zeaxanthin, you are not only getting lutein and zeaxanthin, but you are also getting fiber, vitamins, minerals, and other phytochemicals. In addition, if you are eating foods high in lutein and zeaxanthin, then you are on some level consuming less of other foods since we can only consume so much food in a day.
However, if you are eating a standard American diet and take a lutein and zeaxanthin supplement, sure, your levels of those two antioxidants will increase, but your overall health may be declining due to the other dietary choices you are making. For example, if you are chronically consuming a surplus of calories, you could gain weight and face the health complications that overweight and obesity bring in spite of having good reaction time.
2. You can either buy food, or buy food AND supplements. We all have to eat and therefore have to purchase or grow our food. If you do not like fruits and vegetables and see supplements as an attractive and cost effective alternative, consider that in addition to purchasing the supplements (which can often be expensive) you will also be purchasing the foods that you do like. While produce can sometimes be expensive (some cases of this include specialty or exotic items and produce out of season), it is generally inexpensive compared to other foods like meat and dairy products (think black beans for protein vs. steak or cheese). It is economical to purchase produce when it is in season, because then the product will be at its highest quality and lowest price (due to supply and demand principles).
This is a very informative topic in an area that I am quite unfamiliar with. But after reading though your blog post, what was most stood out to me, is that a more efficient central nervous system can result in improved reactive time. In my brief exposure to cognitive function, reactive time is so important in so many aspects of functionality, but it also essential for athletes who have suffered concussions. I have learned through various seminars, that a change in reaction time is one of many clinical measures that are continuously monitored after an athlete suffers a concussion. I immediately thought, would introducing carotenoid supplements aid in recovery?
That is a great thought. Concussion patients would be a very interesting population in which to study lutein and zeaxanthin supplementation. You should send an email to Dr. Hammond! In order to answer that question you would most likely want a case control study. Half your participants would have suffered a concussion, and they would be matched to similar individuals who have not had a concussion.
Great job on this blog post! The information you provided is thorough and informative, and written in a clear and concise manner. As a researcher, I’m curious about the testing conducted in Dr. Hammond’s studies, as well as the length of the intervention. What tests did they conduct to measure visual processing speed, cognitive function, and neural activity? How long were the participants taking the supplement and how often were they tests?
The data presented in the seminar came from numerous studies with different designs. I looked up one to answer a few of your questions. In one of Dr. Hammond’s papers (A Double-Blind, Placebo-Controlled Study on the Effects of Lutein and Zeaxanthin on Neural Processing Speed and Efficiency) participants were supplemented for four months with either placebo (n = 10), zeaxanthin only (20 mg/day; n = 29) or a mixture of 26 mg/day zeaxanthin, 8 mg/day lutein, and 190 mg/day mixed omega-3 fatty acids (n = 25). Neural processing speed and efficiency were measured by critical flicker fusion (CFF) thresholds, and visual motor reaction time. As this is not my area of expertise I cannot thoroughly explain the experimental testing, but if you’d like more detail you can use the UGA database to read more about Dr. Hammond’s work with lutein and zeaxanthin!