Berries and other brightly coloured fruits tend to hog the health headlines, but an apple a day may still keep the doctor away when it comes to cardiovascular health.
According to a 2019 review, observational studies found a significant reduction in the risk of cerebrovascular disease (including strokes), cardiovascular disease and type 2 diabetes as a result of eating apples and pears.
The review also included randomised controlled trials – considered the gold standard for proving cause and effect – and they found that apples significantly reduced body mass index in the short term but did not significantly affect cardiovascular health.
However, a recent clinical trial has demonstrated that eating two apples a day lowered cholesterol levels and improved other cardiometabolic biomarkers in adults with high cholesterol.
The trial, published in February in the American Journal of Clinical Nutrition, involved 23 women and 17 men aged about 50. One group ate two renetta canada apples a day and the other drank a sugar-and-energy-matched apple beverage for eight weeks. After a four-week washout period, the groups swapped over.
The trial revealed that eating two of the proanthocyanidins-rich apples each day resulted in reduced total cholesterol, LDL cholesterol and triglycerides. It also improved other cardiovascular biomarkers, but it didn’t reduce blood pressure.
These findings are consistent with those of laboratory studies demonstrating the health benefits of apples. Although the composition of phytochemicals in apples varies greatly between varieties, laboratory studies have found apples typically have very strong antioxidant activity, inhibit cancer-cell proliferation, decrease lipid oxidation and lower cholesterol. This is possibly due to the presence of flavonoids, anthocyanins and other antioxidants. Indeed, these bioactive compounds, along with dietary fibre, have been individually linked to reductions in various cardiovascular disease risk factors and events.
Storage has little to no effect on the levels of phytochemicals in apples. For example, anti-inflammatory and anti-allergic quercetin remained constant in four apple varieties, even after 52 weeks of controlled atmospheric storage, in one study. Another study found the total volume of phenolic compounds, of which flavonoid antioxidants are a sub-group, remained much the same after 200 days of storage.
However, processing of apples does result in a significant decrease in their antioxidant content. Anywhere from 58% to 97% of antioxidant activity is lost when apples are juiced. Most antioxidants are found in the apple skin, so peeling them causes significant losses, too.
So you’re better off choosing apple juice based on its taste rather than any supposed health benefits advertised for it.
If you prefer to eat produce in season only, most fruits and vegetables provide a generous supply of vitamins, minerals and dietary fibre as well as many other phytonutrients, says the Ministry of Health.
It recommends we eat at least three servings of vegetables and two or more servings of fruit a day. However, nearly half of New Zealand adults (43%) were not meeting the guidelines for fruit when a 2013/14 survey was conducted. One serving of fruit is equivalent to:
- 1 medium-sized apple, pear, banana or orange
- 2 small apricots or plums
- ½ cup of fresh fruit salad
- ½ cup stewed fruit (fresh, frozen or canned)
For a portable nutritious snack, it’s hard to go past an apple.
This article was first published in the March 21, 2020 issue of the New Zealand Listener.