In the news: Vitamin C & Cataract; Overnight Fast Time in Early Breast Cancer

Influence of Nature vs. Nurture on Cataract

Growing older, smoking, oxidative stress and antioxidant intake are factors that have been associated with nuclear cataract, the most common age-related type of cataract or clouding of the eye’s lens. The genes we inherit are also thought to play a role in susceptibility to cataract formation.

Specific genes have recently been linked to nuclear cataract development in Asian populations, but little is known about genes associated with cataract risk in other populations.

One way to learn more about the influence of nature vs. nurture is to study pairs of twins, who share most of the same DNA. To gain insight into the relative importance of genes and the connection between antioxidants and nuclear cataract progression, UK researchers studied 324 pairs of twins. About 150 of the twins were identical, and the rest were fraternal. The investigators assessed the twins’ lenses and diet and followed them for about 10 years.

Vitamin C-rich Diets May Help Save Sight

At the study’s start (1), eating more vitamin C-containing foods and at least 2 fruit and 2 vegetable servings daily translated to about a 20% lower risk of cataract.

Nine to ten years later, those twins who consumed more dietary vitamin C – at least 150 mg daily – had a 33% lower risk of cataract progression versus those who consumed less. The researchers believe that tears higher in vitamin C bathe the lens and better protect them from oxidative stress.

According to the researchers, genetic factors explained 35% of the difference in progression of nuclear cataract over a 10-year period, while 65% was due to environmental factors like diet.

What about vitamin supplements? In this study, no association was found between the use of dietary supplements and cataract. However, fewer than 10% of participants reported using any individual supplement, so all supplements were grouped together. That makes it difficult to draw conclusions about the effect of any single supplement or of any supplement ingredient (e.g., supplemental vitamin C) on cataract.

Bottom line: A healthy diet overall may help protect our eyesight – one that includes vitamin C-rich foods such as oranges, papayas, cantaloupes, bell peppers, strawberries, kiwis, broccoli and dark green leafy veggies.

Breast Cancer: Does It Matter When We Eat?

Much of the research conducted on diet and breast cancer to date has focused on what to eat to help prevent this cancer, such as specific foods, food groups and overall dietary patterns. But a new theory has emerged that when we eat also matters, with research showing that timing of food intake influences metabolic health and cancer.

A landmark study with mice, for instance, showed that a 16-hour bedtime fasting regimen protects mice on a high-fat diet from abnormal glucose metabolism, inflammation, and weight gain. And in an analysis of over 2,100 diabetes-free women, longer nightly fasting was associated with significant improvements in markers of blood sugar control.

In a new analysis (2) of 2,400 participants in the Women’s Healthy Eating and Living Study, the relationship between eating before bedtime and cancer outcomes were tested. The women had early stage breast cancer, were not diabetic, and were followed for over 11 years.

Those who fasted less than 13 hours each night had a 36% higher risk for breast cancer recurrence vs. women who didn’t eat for 13 hours or more. No link between shorter nighttime fasts and higher risk of death was seen.

Closer examination revealed that each 2-hour increase in nightly fasting was linked to longer nighttime sleep and lower HA1c levels – an important indicator of blood sugar control. While more studies are needed to confirm these results, prolonging nighttime fasting may be a simple strategy for helping to prevent breast cancer from returning, according to the authors.

References

1. Yonova-Doing E., et al. Genetic and dietary factors influencing the progression of nuclear cataract. Ophthalmol [ePub ahead of print Mar 15, 2016].
2. Marinac C.R., et al. Prolonged nightly fasting and breast cancer prognosis. JAMA Oncology [ePub March 31,2016].