The famous Skittles’ tagline – “Taste the Rainbow” can be applied to fruits and vegetables. Specifically, it can be applied to the carotenoids found in fruits and vegetables.
Carotenoids are broken down into two distinct categories – Xanthophylls, which contain oxygen, and carotenes, which do not contain oxygen. Two characteristics that unite both xanthophylls and carotenes are that they are both fat-soluble and cutting/chopping and cooking the source produce containing them increase their potency when entering the bloodstream.
Another keen factoid: Fruits and vegetables are the easiest direct food source to obtain your nutra-hues because as humans, we can’t synthesize these on our own – they need to be provided via diet.
There are more than 750 identified carotenoids that provide colors ranging from yellow to deep purple; and some carotenoids are also found in algae, shrimp, krill, and photosynthetic bacteria. (White vegetables such as cauliflower and white carrots do not contain any significant amount of carotenoids, by the way.)
Carotenoid content varies in the same type of fruit or vegetable depending on color. One comparative study looked at the carotenoid profiles of three colors of corn – white, yellow and black The researchers found that the black corn had the highest quantity of anthocyanins (a type of carotenoid subgroup) while white corn had the lowest amount and yellow corn’s carotenoid content came in between.
Greens are also a source of popular carotenoids such as lutein and carotenes (both found abundant in red-orange-yellow produce). And here’s a fun fact: a study that will be published in the September 2021 issue of Food Chemistry explores the carotenoid content of ferns. The authors examined 37 edible fern species and found that those in the Athyriaceae family are rich in lutein, while some ferns in the Dryopteridaceae family have a good amount of β-carotene.
Current Carotenoid Research
The most commonly consumed carotenoids are yellows/oranges/reds. These are also among the most researched. One currently ongoing trial is investigating the role of probiotic supplementation in carotenoid status in vivo – meaning, do probiotics enhance viability of dietary-consumed carotenoids that have been made bioavailable to blood and skin?
The hypothesis on which this study was designed is explained by the authors: “Carotenoids have demonstrated antioxidant, anti-inflammatory, and anti-obesogenic properties among others. Excess carotenoids are deposited in the skin for storage where they protect against UV skin damage and contribute to improvements in skin health (i.e., decrease the appearance of wrinkles). However, carotenoid status is linked to bioavailability and absorption, which has a high inter-individual variability. It has been hypothesized that inter-individual variations are related to the diversity of gut microbiota.”
In the study, 50 pre-menopausal women are taking either one capsule of 20 mg total carotenoids plus placebo or the carotenoid plus a proprietary probiotic strain for 10 weeks. Secondary outcomes being determined include changes in skin hydration, skin elasticity skin trans-epidermal water loss, and facial skin wrinkling.
The study, entitled, “Probiotics for Enhanced Tissue Carotenoid Status: a Double-Blind, Randomized, Controlled Trial” is set to be completed next month (May 2021).
Lycopene is known originally in the natural health product industry as a men’s health supplement, as it has been shown to support prostate health. A new study shows another side to lycopene – that of sports nutrition/strength. The authors investigated the role of lycopene in supporting muscle-fiber type in vivo and in vitro, and found that after 8 weeks of administration, lycopene promoted the expression of slow-twitch fibers, and enhanced mitochondrial respiratory capacity. The authors believe that “lycopene affects the muscle-fiber type through aerobic oxidation, suggesting that lycopene exerts potential beneficial effects on skeletal muscle metabolism.”
A recently published systematic review focused on the viability of lycopene supplementation in various lung disorders with the authors concluding that research in this area “provides convincing evidence” for future human clinicals in the area of pulmonary health.
Astaxanthin, a pinkish-red pigment commonly obtained from shellfish and red algae, has several benefits, one being the so-called “beauty from within.” It has been widely researched as a compound that supports DNA repair in skin tissue, acts as a photoprotective agent and manages inflammation in skin from UV exposure.
One systematic review analyzed clinical evidence of astaxanthin supplementation on skin health. In many of the randomized, controlled trials reviewed by the authors, astaxanthin supplementation was found to improve skin texture, appearance (wrinkles), and moisture content at the end of the study periods. Astaxanthin also appeared to protect against UV-induced skin damage. Overall, there is some clinical data to support the benefits of astaxanthin supplementation (in the range of 3 to 6 mg/d) on skin health, especially for photoaged skin.
Astaxanthin may also be more prominent in women’s health formulas in the near future. The aim of a randomized placebo-controlled clinical trial that is currently being completed is to examine the effects of a daily dose of 8 mg astaxanthin in 48 women with PCOS. The team is seeking to discern potential reduction in free radicals (reactive oxygen species) in follicular fluid (which helps form healthy, viable eggs).
This dynamic duo’s primary power is to protect vision and support eye structure. One team wanted to look at how lutein and zeaxanthin combined with choline affected on cognitive performance in 80 middle-aged overweight and obese adults and found that after seven days of consuming the nutrients, higher intake of lutein-zeaxanthin and choline was associated interactively, but not independently, with faster reaction time on cognitive flexibility tasks. This means that carotenoids perform better together in this manner than they do by themselves.
A mechanism of action of lutein in fat cell creation (adipogenesis) was revealed in a new study. Lutein has been shown to inhibit adipogenesis through stopping the fat cell differentiation process; it does so by halting early phase regulators involved in this process.
Wondrously, there are more carotenoids and a ripening field of studies on them. A study to be published in the June 2021 issue of the Journal of Nutrition Biochemistry shines a light into the near future of carotenoid and produce-pigment research into human health, because there has been a definitive shift in dietary habits from eating processed and synthetic foods to semi-processed, more natural and fresh fruits and vegetables in the quest for a healthy life. In agriculture, this exciting shift is spurring improvements in newly popularized produce crops – for example, orange and purple cauliflower, and black and purple carrots -- resulting in enriched color compounds. The authors of this paper assert that their review is “devoted to a better understanding of vegetable colors with specific health benefits and to provide in-hand information about the effect of specific pigment on body organs, the effect of processing on their bioavailability, and recent improvements in colors to ensure a healthy lifestyle.”
They encourage the undertaking of “exhaustive laboratory trials” to document and establish minimum effective concentrations, bioavailability, and specific health benefits of these carotenoid and related bioactive compounds.
This is an exciting area of research that will eventually inform development of more accurate and efficacious supplements. Stay tuned!