In the news: Pistachios for Macular Health; Crucifers May Lower Cancer Risk

Pistachios = a Great Snack for the Eyes

We all know that nuts provide many health benefits, from lowering levels of inflammation to supporting heart health. Nuts are, afterall, a staple of the Mediterranean diet – a way of eating that’s been associated with overall long term health.

Pistachio nuts contain an abundance of healthful nutrients including antioxidants, potassium, fiber, good quality protein and monounsaturated fats. But it’s pistacho’s content of the carotenoids lutein and zeaxanthin that’s been of recent research interest.

Can snacking on these nutritious nuts actually provide benefits to the eye? Investigators at Friedman School of Nutrition Science and Policy,Tufts University set out to answer this question.

The new study(1) examined the effects of consuming 57 g (about 2 ounces) daily of shelled pistachios in thirty-two healthy adults aged 60 years on average. The participants were eating only about 2 mg of lutein and zeaxanthin daily, considered a low intake.

Participants in the study also had low density of macular pigment. Macular pigment optical density or MPOD is a measure of the density of macular pigment composed of lutein, zeaxanthin and mesozeaxanthin that helps protect the retina from light damage.

The more macular pigment in the retina, the better protection it offers. Low MPOD is a risk factor for age related macular degeneration.

The particpants ate their usual diet along with the pistachios, and were compared to a control group also consuming a typical diet but without the added nuts.

At the end of 6 weeks, MPOD was significantly increased in the pistachio group compared to controls. This benefit persisted to the trial’s end at 12 weeks.

Blood levels of lutein also increased for those in the nut group vs. controls, though blood levels of zeaxanthin did not change in either group.

Each 2-ounce serving of pistachios contained about 1.65 mg of lutein / zeaxanthin – a much lower amount than is typically found in dietary supplements. How-ever, the lutein contained in pistachios is highly bioavailable.

Choosing pistachios as a snack could be a good dietary strategy to support MPOD and to augment carotenoid supplements in helping to preserve eye health.

Can Crucifers Lower Pancreatic Cancer Risk?

Rates of pancreatic cancer have risen in recent years. It’s now the 4th leading cause of cancer deaths in the US largely because it is diagnosed only at late stages of the disease.

This has led to a search for ways that we might lower the risk for this cancer, such as stopping smoking.

In terms of diet and risk, one theory is that cruciferous vegetables contain phytochemicals that might beneficially affect the process of bile production – thought to be a factor in this type of cancer. Studies, however, have not had consistent findings: some have linked greater intake of crucifers with lower risk, others have not.

A recent review(2) of 16 observational studies found that the highest intake of crucifers was associated with a 17% risk of pancreatic cancer compared to the lowest intake, especially in studies conducted in the US. One problem, though, was that some of the research was not of the highest quality design.

Examples of cruciferous vegetables are arugula, bok choy, broccoli, brussels sprouts, cabbage, cauliflower and collard greens. All of these veggies support general wellness, and may help lower cancer risk too.

References

1. Scott TM, et al. Pistachio consumption increases Macular Pigment Optical Density in healthy adults: a randomized controlled trial. J Nutr. S0022-31, 2024.
2. Zhang G. Cruciferous vegetable intake reduces pancreatic cancer risk: an updated systematic review with meta-analysis. Eur J Nutr. Epub July 30, 2024.