Macular carotenoids shown to have heart health benefit
The three macular carotenoids — lutein, zeaxanthin and meso-zeaxanthin — were shown in a study to have antioxidant properties that could have implications for heart health.
At a Glance
- Lutein, zeaxanthin and meso-zeaxanthin are key eye health ingredients.
- They protect the eye via antioxidant activity and blue light absorption.
- This study shows they could also help protect the heart, too.
Is the eye bone connected to the heart bone?
A new study revealed that the renowned vision-health macular carotenoids have antioxidant properties which could be beneficial in restricting the formation of arterial plaques. This plaque buildup is known as atheroscolerosis, and it reduces blood flow to the heart and increases the risk of blood clots. Such blood clots that block an artery can lead to a heart attack as well as stroke and other complications.
The research was published in the journal Nutrition, Metabolism and Cardiovascular Diseases. It was the work of researchers associated with the Nutrition Research Centre Ireland and Northern Arizona University.
The study focused on supplementation with lutein, zeaxanthin and meso-zeaxanthin. These carotenoids have been exhaustively studied for their role in visual health.
Vital role within the eye
The three carotenoids, which collectively are a subset known as xanthophylls, are selectively concentrated within the macula. The macula demands a lot of oxygen to perform its vital function, so it’s sensitive to oxidative stress and leans heavily on the antioxidant function of the xanthophylls. Additionally, the three xanthophylls together are colored a bright yellow, a secondary color that is opposite on the color wheel from the primary color blue. Thus, via the physics of the visible light spectrum, they have a function in absorbing potentially harmful blue light. This both accentuates visual acuity but also improves night vision.
However, the eyes are not the only place where oxidative stress can lead to damaging changes in the body over time. Oxidative stress plays a role in atherosclerosis too, the authors of the present study note.
Possible role in prevention of atherosclerosis
“Oxidative stress is one of the most salient risk factors in the pathogenesis of atherosclerosis,” the researchers wrote. “Mechanistically, the oxidation of low-density lipoprotein (LDL) particles within the vascular endothelium has been hypothesized to be the initial event that occurs in the formation of atherosclerotic plaques.”
The data for the present study was derived from a study dubbed COAST (Carotenoid Omega Study). A total of 80 subjects completed the six-month trial.
The subjects, all from the Waterford, Ireland, area, averaged about 44 years of age. The group was about evenly split between men and women. The subjects were all normal weight to moderately overweight, with no statistically significant differences between the groups. The diets of the participants were not evaluated.
The larger trial included four distinct groups, a placebo group and three groups that received the three carotenoids in three distinct delivery forms. Those were carotenoids encapsulated in micelles or suspended in either sunflower oil or omega-3 fish oil. For the purposes of the present study the three carotenoids group were treated as a single group.
The dosage used was 10 mg of lutein, 2 mg of zeaxanthin and 10 mg of meso-zeaxanthin. The carotenoids were supplied by a Mexican manufacturer, Industrial Organica, which also provided some funding for the trial.
Xanthophylls shown to have antioxidant effect
The study found a statistically significant difference in the amount of oxidized low-density lipoprotein (LDL) and inflammatory cytokines in the blood of the experiment group compared to the placebo group. While showing this result with antioxidant molecules derived from plant sources is hardly novel, the researchers noted this is the first study to demonstrate this with the macular carotenoids when supplement directly in humans.
“In sum, our data show that macular xanthophyll supplementation can decrease serum pro-inflammatory cytokines and OxLDL, and by extension may limit atherosclerotic plaque formation by disrupting the oxidation of LDL, which is a necessary step in foam cell formation, intimal wall deposition, and continuation of the inflammatory feedback loop,” they concluded.
Possible omega-3 effect discounted
The researchers noted that the inclusion of omega-3 oil, a known anti inflammatory agent, in one of the three intervention groups was a possible confounding factor.
“However, in our post hoc analysis, oil suspension (sunflower vs. omega-3s) did not show any statistically significant differences for any parameters of interest, which supports the idea that L, Z, and MZ are the primarily factors influencing the observed reductions,” they noted.
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