Study links cis-beta-carotene to myopia risk in teenagers
Writing in the journal Frontiers in Nutrition, Chinese and Australian researchers examined data from the 2003–2006 National Health and Nutrition Examination Survey (NHANES) and reported that cis-β-carotene intake should be carefully controlled in dietary supplements, especially for individuals between the ages of 12 and 19 years.
“While past research indicated that cis-β-carotene is beneficial for the retina, some studies have found adverse effect,” they wrote. “Although β-carotene as an antioxidant may theoretically protect the retina by reducing oxidative stress, high doses of β-carotene supplements were reported to have strong side effects, including mitochondrial dysfunction and increased oxidative stress, negatively impacting retinal cells.”
Micronutrient research needed
Myopia, also described as nearsightedness or short-sightedness, is a public health concern impacting adolescents in some parts of the world at 80% to 90%. According to the study, myopia is prevalent among school-aged children in North America at 42%. It can lead to conditions such as retinal detachment, glaucoma and irreversible vision loss.
Research demonstrates the role of micronutrients in promoting eye health, including vitamin A, which helps maintain normal vision and prevents night blindness.
“High-dose vitamin C and E supplements may delay the progression of age-related macular degeneration and improve vision,” the investigators noted. “Carotenoids, by reducing reactive oxygen species, inhibiting inflammation and suppressing inflammatory markers, have shown significant preventive and therapeutic benefits for age-related ocular abnormalities.”
However, the relationship with myopia and micronutrients (vitamins A, C, D, E, α-carotene, trans-β-carotene, cis-β-carotene, lutein, and zeaxanthin) for eye health is not well understood. The study investigated the connection between serum micronutrient levels and data from NHANES to determine insights into how potential nutritional interventions might slow or prevent the progression of myopia.
Study details
The study included 1,620 adolescents between the ages of 12 and 19 years. Scientists collected blood samples from participants at a mobile examination center. Serum levels of vitamins A, C, E and carotenoids were measured by a high-performance liquid chromatography and multi-wavelength photodiode array absorbance detection. Vitamin D was measured using the DiaSorin RIA kit.
Myopia impacted 32% of the participants while 68% were classified as non-myopic.
“Our results indicated that higher serum cis-β-carotene levels were associated with an increased risk of myopia and high myopia in adolescents,” the researchers concluded. “In this study, only cis-β-carotene was significantly positively associated with myopia risk, while trans-β-carotene did not show a significant association. Previous studies have indicated that the energy barrier for reverse cis-to-trans isomerization is lower than that for direct isomerization, allowing cis isomers of carotenoids to react more rapidly with free radicals.”
The scientists hypothesized that the accumulation of cis-β-carotene could increase local oxidative stress and lead to structural and functional changes in the retina, impacting the development of myopia.
Other micronutrients, such as vitamins A, D, E, C, α-carotene, trans-β-carotene, lutein and zeaxanthin, did not have statistical significance when associated with adolescent myopia.
The researchers explained that because β-carotene is an exogenous rather than endogenous antioxidant, “caution should be exercised when considering β-carotene supplements for young people.”
Source: Frontiers in Nutrition
doi: 10.3389/fnut.2024.1477403
“Association between micronutrients and myopia in American adolescents: evidence from the 2003–2006 National Health and Nutrition Examination Survey”
Authors: Kunhong Xiao et al.
