Nutrition Bytes: June 2023

Lutein Supplements Improve Visual Performance and Sleep

Today’s modern lifestyle has led to a significant increase in screen time and blue-light exposure, which are associated with eye strain and fatigue, inability to focus, and sleep problems. Cumulative and long-term exposure to blue-light emitting screens and lights have also raised concerns about potential cellular damage to the retina of the eyes due to increased levels of oxidative stress. With average screen time use exceeding 10 hours per day, researchers are finding that a natural compound called lutein can mitigate some of these effects.

Lutein and its nutrient co-partners, zeaxanthin and meso-zeaxanthin, are of particular interest since they preferentially accumulate in high concentrations within the retina of the eye and are known to absorb blue light. Lutein is naturally found in dark leafy green vegetables, including spinach and chard, which are largely under-consumed by most Americans.

Child with eye-strainA 2017 study1 examined the effects of a supplement containing 24mg of lutein, zeaxanthin, and meso-zeaxanthin on 35 healthy college-aged subjects over a six-month period and compared the results to a placebo group. All subjects had 20/20 vision at the start of the study and were exposed to a minimum of six hours of daily screen time at a distance of three feet or less. Several measures of visual and physical health were taken at the beginning of the study, at three months, and at six months. 

The researchers found that six months of lutein supplementation significantly increased the subjects’ macular pigment optical density (MPOD), which is a measure of lutein concentrations within the retina of the eye. This increase in MPOD was also significantly correlated with improvements in all measures of visual performance. Additionally, by the end of the study subjects taking lutein saw a significant reduction in the frequency of headaches, eye strain, and eye fatigue, as well as a significant improvement in sleep quality. The researchers concluded that the effects of lutein likely work by not only absorbing blue light, but also by having an antioxidant and anti-inflammatory effect throughout the body.


Pycnogenol Improves Glucose Control and Combats Erectile Dysfunction in Diabetic Men

According to one statistic, men with diabetes are at a three-fold greater risk for erectile dysfunction (ED) compared with nondiabetic men.2 This occurs because chronically elevated blood sugar damages the blood vessels and nerves needed to control an erection, leading to sexual dysfunction. New research suggests that Pycnogenol, a natural compound found in French maritime pine bark, can combat ED in diabetic men. Further, it can also support healthier lipid (including total and LDL cholesterol) and blood sugar levels.

In this randomized, placebo-controlled trial, men with ED, including those with and without diabetes, were divided into two groups. One group was instructed to take 120mg Pycnogenol daily, while the other was given a placebo for three months. The degree of ED was assessed several times throughout the study period, in addition to one month after stopping the intervention. Biochemical parameters of glucose control and total and LDL cholesterol were also measured.

In the Pycnogenol group, ED among the diabetic men improved by 45 percent, compared to 22 percent in men without diabetes. The men receiving the placebo reported no significant changes. Diabetic men receiving Pycnogenol also saw significant improvements in measures of glucose control as well as significant reductions in total and LDL cholesterol.

Due to its ability to improve glucose control as well as comorbid conditions like ED, researchers concluded that Pycnogenol offers beneficial treatment effects in men with diabetes.3


  1. Stringham, James, et al. “Macular Carotenoid Supplementation Improves Visual Performance, Sleep Quality, and Adverse Physical Symptoms in Those with High Screen Time Exposure.” Foods, vol. 6, no. 7, June 2017, p. 47, doi:
  2. Maiorino, M., Bellastella, G., etl al. (2014). Diabetes and sexual dysfunction: current perspectives. Diabetes, Metabolic Syndrome, and Obesity: Targets and Therapy, 7:95-105. Retrieved from
  3. Trebaticky, B., Muchova, J., et al. (2019). Natural polyphenols improve erectile function and lipid profile in patients suffering from erectile dysfunction. Bratisl Med; 120(12):941-944. Retrieved from