What are the health benefits of apples?

BY Samuel Mathis, MD, Assistant Professor, UTMB

 

I’ve always found the phrase, “An apple a day, keeps the doctor away” to be humorous. As a child, I imagined that doctors responded to apples in the same way vampires responded to garlic. Interestingly enough, it turns out that there may be some truth to the phrase. Apples have some amazing health benefits that can keep us and our patients healthy and lower the risks of certain diseases.

 

Apples are fruits that are packed with nutrients, vitamins, antioxidants, and fiber. Apples are low in sodium, fat, and cholesterol. They also have high amounts of Vitamin C which is necessary for growth and development and is vital to the repair of cells and tissues. Vitamin C is a powerful antioxidant that helps improve immunity and protect our cells from oxidative damage caused by processed high-sugar foods. A recent review and systematic analysis of Vitamin C showed a dose-dependent response of Vitamin C with all-cause mortality, cardiovascular disease, esophageal cancer, gastric cancer, cervical cancer, and lung cancer (1).  The antioxidant effect of Vitamin C improves the immune system’s response to infections, decreases the risk of heart disease, and can even improve blood pressure. Another benefit of Vitamin C is its effect on enhancing iron absorption in the diet. This can be effective in helping some individuals with anemia. I typically recommend individuals drink orange juice with their iron supplementation, but pairing the medication with an apple may have a similar effect. One apple has 7-10 mg of Vitamin C (~10% of our daily recommended intake). Other nutrients found in apples include copper, potassium, as well as Vitamins K, E, B1 and B6.

 

At just 100 calories, a medium size apple can be a fantastic snack for people trying to lose weight. Apples increase the feeling of fullness through their high fiber content, thus prompting patients to eat less. Additionally, apples are packed with numerous polyphenols that also work on improving weight and better utilization of fat stores. Studies have found that a Mediterranean plant-based diet rich in polyphenols caused more weight loss than the same style diet that primarily utilized meat (2). Polyphenols also play a role in management of blood sugar levels, decreasing inflammation, improving digestion, and may even play a role in decreasing cancer risk. They also help control blood pressure and decrease the risk for heart disease.

 

Another benefit of apple consumption is the digestive benefit. Apples skins are high in fiber and act as a pre-biotic. The primary way apples do this is through a starch called pectin. Pectin has been linked with improved intestinal microbe regulation, intestinal permeability, and inflammation response. There is research now looking at our gut health and how it affects the progression of certain chronic diseases such as obesity, diabetes, heart disease, and cancer. One study found that freshly harvested apples have better effects than conventional store-bought apples (an even bigger reason to check out the local farmer’s market!).  Apples may also help symptoms of acid reflux, though green apples may worsen it due to their acidity. It is the fiber count of apples that actually makes them a low-glycemic fruit. Despite the average 19 grams of sugar per apple, the amount of fiber (20% of daily need) makes apples a low glycemic index of 39.

 

Finally, apples may have some health benefits for the brain. The flavonoid quercetin may protect our brain from oxidative stress. A review of quercetin’s effect in brain disease found that chronic treatments with quercetin improve the regulation of proteins, transcription factors, and survival signaling cascades in brain tissues (3). A medium apple contains about 10 milligrams of quercetin.  For full benefits, doses of 250-1000 mg. have been studied, so the amount in one apple is not enough to see full beneficial effects.  This possibly lowers the risk of developing certain dementias and cognitive decline. However, further research is needed to confirm these results are seen in individuals who eat apples.

 

To finish our conversation, I will leave you with this. A 2015 study did look at apple consumption and physician visits. This study looked at 8399 participants and their apple consumption (4). Those who ate apples consistently were less likely to see a physician (39% vs 33% of physician avoidance p= .03), though that finding was not statically significant once accounting for sociodemographic and health-related characteristics. Thankfully, the statement is not true. Apple consumption does not keep doctors away. Patients will still need us despite their apple consumption.

 

Citations:

1. Xu K, Peng R, Zou Y, Jiang X, Sun Q, Song C. Vitamin C intake and multiple health outcomes: an umbrella review of systematic reviews and meta-analyses. Int J Food Sci Nutr. 2022 Aug;73(5):588-599. doi: 10.1080/09637486.2022.2048359. Epub 2022 Mar 15. PMID: 35291895.
2. Castro-Barquero S, Lamuela-Raventós RM, Doménech M, Estruch R. Relationship between Mediterranean Dietary Polyphenol Intake and Obesity. Nutrients. 2018 Oct 17;10(10):1523. doi: 10.3390/nu10101523. PMID: 30336572; PMCID: PMC6213078.
3. Dajas F, Abin-Carriquiry JA, Arredondo F, Blasina F, Echeverry C, Martínez M, Rivera F, Vaamonde L. Quercetin in brain diseases: Potential and limits. Neurochem Int. 2015 Oct;89:140-8. doi: 10.1016/j.neuint.2015.07.002. Epub 2015 Jul 6. PMID: 26160469.
4. Davis MA, Bynum JP, Sirovich BE. Association between apple consumption and physician visits: appealing the conventional wisdom that an apple a day keeps the doctor away. JAMA Intern Med. 2015 May;175(5):777-83. doi: 10.1001/jamainternmed.2014.5466. PMID: 258221