An increasing number of studies have associated higher carotenoids level with lower risk to develop major health conditions such as cardiovascular diseases, certain types of cancer, neurodegenerative disease and even metabolic disorders. Carotenoids level is also strongly related with aging and skin quality.
Many of these studies can be found one One X / Science
Let’s review some of the most interesting ones and understand the underlying mechanism behind them.
Early Research (1984) has been carried showing relevant association between tissue carotenoids level and longevity. In his study, R. Cutler has reviewed the blood and tissue concentration of carotenoids in 13 different mammals including primates (Humans and monkey species) and non-primates (horse, cow, goat, rabbit, etc..). The Researcher defines the term “MLSP” as maximum lifespan potential and shows a 83% correlation between tissue carotenoid level (in the brain) and longevity in all mammals analyzed.
More recently, papers have started to study the potential correlation between the buzzy aging biomarker “telomere length” and carotenoid level in blood. (Telomere length shortens with age and lead to progressive senescence). A study published in Jan. of 2016 carried on 3660 participants concludes: “high levels of blood carotenoid were significantly associated with longer leukocyte telomeres in US adults. High intake of carotenoid-rich food may play a role in protecting telomeres and regulating telomere length”
An earlier 2014 study carried in Austria also found similar results, looking at different carotenoids (lutein and zeaxanthin in this case)
And just last week (Sept 2016), the European union released a study carried in six European countries over a cohort of 2118 individuals showing a significant negative relation between aging and carotenoids (mostly lycopene and a/b carotene)
Research on the role of carotenoids in cancer prevention is gaining increasing scientific focus.
Indeed carotenoids, a class of 600+ pigment molecules are known for their antioxidant properties but also for their signaling characteristics.
B-carotene, a major carotenoid molecule, also known as provitamin A from its potential to be converted to retinol (Vit. A), has also independent functions: for example, the ability to restore cell communication, usually hacked by cancer cells in order to escape control from the immune system. At such beta-carotene can upregulate the production of “connexin protein” responsible of the intra-cellular junctional communication
Interesting inverse correlations have been observed between serum / tissue carotenoids and cancer types such as:
Breast cancer (2016 study): “serum α-carotene, β-carotene, lycopene and lutein/zeaxanthin were inversely associated with breast cancer risk among premenopausal women and among all subtypes
Previous findings had shown a negative association between prostate cancer and lycopene, the second most abundant carotenoid present in human tissue after beta carotene
Another academic focus has been put on cardiovascular diseases, the first death cause worldwide,
Many studies show that the benefits from fruit and vegetable consumption to prevent artherosclerosis could actually come from carotenoid consumption
Familiar with the so-called “Mediterranean diet” ?
One carotenoid molecule, lycopene, actually distinguishes itself as the most potent antioxidant protection agent against LDL oxidation, the hallmark of cardiovascular disease progression (And not serum cholesterol levels as most doctors continue to routinely measure): “Although there was no change in serum cholesterol levels (total, LDL, or high-density lipoprotein), serum lipid peroxidation and LDL oxidation were significantly decreased”
We can also find relevant connections between carotenoids intake with neurodegenerative disease and cognitive decline:
In this study of 2009, higher cognitive performance of 94 people aged above 45, were associated with higher blood levels of carotenoids.
Guest and Grant recently conducted a comprehensive scientific review to assess the evidence on the association between blood levels or dietary intakes of carotenoids and risk of neurodegenerative diseases such as Parkinson and Alzheimer:
“Significant evidence indicates that an increased intake of dietary carotenoids reduces the rate of age-related cognitive decline and risk of several neurodegenerative disorders (Johnson et al. 2013; Renzi et al. 2014; Suganuma et al. 2002). Research suggests that these beneficial effects are mediated by a variety of mechanisms activity a includes to their pro-vitamin A activities include antioxidant, anti-inflammatory, and hypocholesterolemic effects”
Diabete and Obesity
Diabete and Obesity prevalence have exploded over the past few decades.
Well, A 2014 study actually shows that people with lower skin carotenoid concentration are indeed much more prone to suffer from metabolic syndrome, the scientific term to designate pre or ongoing conditions leading to obesity and other chronic diseases.
Metabolic syndrome is also associated with insulin resistance and high fasting glucose in the concerned individuals. A Finnish study has actually shown that, in men, dietary carotenoids are inversely associated with fasting plasma glucose concentrations and plasma beta-carotene concentrations are inversely associated with insulin resistance
Furthermore, a recent and very interesting study from the Human Nutrition Research Center on Aging at Tufts University (Boston) has shown that breastmilk from obese mothers contains much less carotenoid than from lean ones, concluding that:
“Breastmilk from obese mothers has a pro-inflammatory fatty acid profile and decreased concentrations of fatty acids and carotenoids that have been shown to have a critical role in early visual and neurodevelopment”
Under the “metabolic syndrome umbrella”, you’ll also find associated liver diseases such as NAFLD (Non-alcoholic fatty liver diseases) (As the name implies, the main characteristic of nonalcoholic fatty liver disease is too much fat stored in liver cells)
An April 2016 study describes the role of Carotenoids as potent antioxidants and anti-inflammatory micronutrients that have been used to prevent and treat NAFLD.
Other areas of Research
Eye Health, specifically AMD (Aged-related macular degeneration) is strongly dependent on sufficient carotenoids bioavailability to the human retina. A 2015 study concluded after two decades of follow-up on a cohort of more than 100K men and women: “Higher intake of bioavailable carotenoids (mainly lutein/zeaxanthin) is associated with a long-term reduced risk of advanced AMD (40% risk reduction)
Carotenoids absorb light in the blue spectrum and as such protect the retina from excess blue light absorption thereby reducing the risk of light-induced oxidative damage that could lead to macular degeneration
Eventually, carotenoids play a critical role in skin protection from UV-A UV-B but also infrared light radiation. Their role in various photosensitive skin diseases has been vastly studied (dermatitis, erythema)
Skin aging is a continuous process and results from intrinsic and extrinsic factors. A number of extrinsic factors often act together to prematurely age our skin. Most premature aging is caused by sun exposure and affects parameters of skin structure and surface. According to Darvin et al. there is a strong correlation between antioxidants found in the skin and skin aging. A high concentration of antioxidant substances in the skin is protective and associated with a reduction in skin wrinkling. His Research team also measured the skin roughness by determining the depth and density of furrows and wrinkle reliefs via profilometry and carotenoid values via raman spectroscopy. They found a high correlation between skin surface structure and the concentration of carotenoids. Subjects of same age with high concentrations of carotenoids showed significantly less wrinkles than those with low carotenoid values. Another study investigated the improvement in the skin surface structure after systemic intake of antioxidants (carotenoids, tocopherol, selenium). Skin density and thickness, roughness, scaling, smoothness and wrinkling were determined. After 12 weeks the verum group showed an increase in skin density and thickness as well as improved values for roughness and scaling.