Overview

In the 19th century, the proverb ‘an apple a day keeps the doctor away’ came into popularity. Over 150 years later the saying is just as apt, only now we have the evidence to back it up. 

There are many different varieties of apples, each one with a slightly different makeup of nutrients, however on the whole they are a delicious, healthy, and readily available food. They are low in calories and sugar and contain fibers, vitamins, antioxidants, and water. They’re also cheap and available most of the year, all over the world. It is no wonder that the apple is one of the most popular fruits on the planet.

This article will give you an insight into the anti-inflammatory effect that apples have on the body and how they can protect you against common chronic diseases. As part of an anti-inflammatory diet, they can also help to reduce the symptoms of some chronic diseases such as rheumatoid arthritis.¹ To truly understand how the anti-inflammatory properties of apples work we will first have a look at what inflammation is, why it happens, and what effects it can have on our health.

What is inflammation?

Inflammation is a consequence of a normal and healthy physiological response by our immune system. It occurs when our body is invaded by a foreign body such as a virus, bacteria, or allergen, or when damage to cells and tissue occurs. When our immune system detects an invader or an injury then a sequence of events is triggered where our cells produce several different chemicals and undertake different tasks to eliminate the invader and repair the damage. An inflammatory response usually produces some pain, swelling, and redness at the sight of inflammation. Whilst acute (short-term) inflammation is our body's way of protecting itself against illness and injury, chronic (long-term) inflammation can itself cause health problems and disease.¹ Chronic inflammation can damage healthy cells and induce a pro-inflammatory state which can increase your risk of developing certain diseases.²

Which diseases can chronic inflammation increase your risk of?

• Cardiovascular disease.
• Metabolic syndrome: a triad of hypertension, hyperglycemia, and dyslipidemia.
• Type 2 diabetes.
• Non-alcoholic fatty liver disease.
• Certain types of cancer eg. colon and breast.
• Osteoporosis.
• Depression.
• Chronic kidney disease.
• Certain auto-immune diseases e.g. Rheumatoid arthritis.

What causes chronic inflammation?

Chronic inflammation can be caused by:

• Oxidative reactions occur which produce free radicals that damage your tissues and cells.³ 
• Failure to eliminate a foreign agent causing acute inflammation which therefore leads to chronic inflammation.³ 
• Auto-immune disorders which cause the body to consistently attack healthy tissues.³
• Exposure to low-level irritants and foreign bodies ie. through inhalation which can not be eliminated

These inflammation-inducing conditions occur due to a range of different factors. ²Here are the most common factors:

• Chronic infections.
• Physical inactivity.
• Obesity.
• Diet eg. saturated fats, processed meats, refined carbs, excess alcohol.
• Intestinal dysbiosis.
• Psychological distress.
• Disturbed sleep.
• Smoking.
• Air pollutants.
• Hazardous waste chemicals.
• Aging.

Antioxidants vs. Anti-inflammatories

The terms antioxidants and anti-inflammatories are often used interchangeably however they are not the same. Antioxidant is a term used to describe any molecule which protects your tissues from ‘oxidative reactions’, these reactions produce free radicals.⁴ Free radicals damage cells and tissue in the body and this damage creates inflammation. It becomes a vicious cycle as inflammation also leads to the creation of free radicals. Antioxidants prevent damage by free radicals and therefore prevent inflammation, so we say that antioxidants have ‘anti-inflammatory properties’. Some compounds, however, like fatty acids, are anti-inflammatories but not antioxidants. They help to signal  the body to resolve the inflammation and therefore reduce overall inflammation but they play no part in preventing the production of harmful free radicals.

Why are anti-inflammatory properties important?

Anti-inflammatory and antioxidant compounds, which are found naturally in many fruits, vegetables, spices, olive oil, and fish are an important component of a healthy diet. They have been shown to protect and reduce the levels of chronic inflammation in the body which in turn reduces your risk of developing certain chronic diseases.⁵ 

There are many different anti-inflammatory and antioxidant compounds found in foods, these can be broken down into different groups: 

• Phenolic compounds are antioxidants with anti-inflammatory properties. There are many different types so they are subdivided further:
  • Simple phenols: phenolic acids and coumarins.⁵
  • Polyphenols: Flavonoids, Stilbenes, Tannins, Lignans. Flavanoids are the largest group of compounds with many of the most important anti-inflammatory molecules found in this group such as Quercetin.⁵
• Unsaturated fatty acids such as omega-3 are anti-inflammatory compounds.

• Ascorbic acid, also called Vitamin C is an antioxidant and anti-inflammatory.
• Bromelain, which is an enzyme extract derived from pineapples.
• Selenium.
• Vitamin E.
• Curcumin.
• Pectin (Fiber).
• Triterpenoids.

Nutritional Composition of Apples

There are many different varieties of apples found all over the world. Each variety of apple will have a slightly different composition of nutrients. However, on the whole, we can say that an apple contains the following nutrients:

One unpeeled medium-sized apple 

• Total weight: 185g
• Calories - 95 kcal
• Water - 156g
• Protein - 0.43g
• Sugars - 18.9g
• Carbs - 25.1g
• Fat - 0.3g
• Fiber (pectin) - 4.37g 
• Vitamin C
• Phenolic compounds: Quercetin, catechin, chlorogenic acid, anthocyanin.

Apples are a very good source of nutrition as they’re low in calories and sugar and high in macronutrients and micronutrients, they also have significant anti-inflammatory properties. 

Key anti-inflammatory properties of apples

There are 4 main nutrients in an apple that help to prevent and reduce chronic inflammation in our bodies.

• Fiber: Pectin is the fiber found in apples. The majority of fiber in an apple is found in the apple peel. Fiber promotes intestinal health and pectin in particular has anti-inflammatory properties which help prevent chronic inflammation.⁶
• Vitamins: Apples contain a variety of different vitamins but in particular Vitamin C. Vitamin C is antioxidant, anti-inflammatory, and helps to lower cholesterol levels. It protects you against diabetes and hypertension and protects your skin from UV-induced photodamage.⁷ 
• Polyphenols: Polyphenols are anti-inflammatory, antioxidant, and antiviral.⁷ Antioxidants have strong anti-inflammatory properties as they prevent the development of free radicals in the body which cause damage and inflammation.⁴ Apples contain multiple different antioxidants in the form of polyphenols and they are one of the main sources of polyphenols in the Western diet.⁸ The main polyphenols found in apples are Flavanoids, Flavanols (catechin, epicatechin, and procyanidins), phenolic acids, dihydrochalcones, flavonols (quercetin), and anthocyanins.⁹ 
• Triterpenoids: These are a group of compounds that are found in many fruits and vegetables including apples. In the apple, they are predominantly found in the peel.¹⁰ They have been discovered to have anti-inflammatory, antiviral, antibacterial, and anti-cancer effects.¹⁰ 

Mechanisms of Anti-Inflammatory Action

• Polyphenols: The mechanism by which these reduce and prevent inflammation has long been studied. They interrupt the cell signaling cascades involved in the production of inflammatory cytokines which promote inflammation.⁸ This means that less inflammatory cytokines are released by immune cells which means that less inflammation is caused.
• Pectin: Pectin plays a role in reducing chronic inflammation by preventing the activation of innate and adaptive immune responses. It does this by binding to ‘toll-like receptors’ found in the gut and preventing them from upregulating pro-inflammatory genes which activate immune responses.⁶
• Triterpenoids: These work to reduce and prevent chronic inflammation by reducing the production of pro-inflammatory cytokines by inhibiting transcription factors and signaling pathways that lead to the production of cytokines.¹⁰
• Vitamin C: Also called ‘ascorbic acid’ is an antioxidant that works to reduce oxidative reactions and prevent chronic inflammation through a variety of different mechanisms.¹¹ The main antioxidant mechanism that it performs is by downregulating the levels of free radicals in the body and increasing the effectiveness of other antioxidants.¹¹

Consumption Recommendations

Daily serving suggestions: It is recommended that you eat 400g of fresh fruit which is equivalent to 2 apples a day.⁷

• Considerations for cooking and processing: Fresh, raw apples are the most nutritious. The skin contains the majority of polyphenols and pectin so it is important to consume this part.¹² Vitamin C is found in the flesh; dehydrating or drying the apple takes away vitamin C. Turning it into juice often removes the fiber and polyphenols, and manufacturers often add in processed sugars.¹²
• Incorporating apples into various diets: Apples are already one of the most popular fruits in the world as they’re healthy, available all year round, and delicious.¹³ You can eat them in various ways, although a raw apple with the skin on is by far the healthiest. They can however be baked, mashed down into a puree, added to salads, or paired with nut butters or cheeses.

Potential Risks and Considerations

• Allergies: A small proportion of the population are allergic to apples, they of course should avoid them. An allergy to apples is often seen in people who have hay fever caused by birch alder and hazel pollen, this is called oral allergy syndrome.
• Interaction with medications: Drinking apple juice can affect the uptake of certain medications such as medications for high blood pressure, diabetes, and mental health conditions. When starting a new medication you should always discuss with your doctor any possible interactions, including interactions with food.
• Moderation: As with any food it is important to consume apples in moderation. Eating too many apples can cause your blood sugars to spike, digestive issues such as bloating and constipation, and damage to your teeth.

Summary

• Apples are amongst one of the most popular fruits to consume around the world.¹³
• They are very nutritious and offer multiple health benefits.
• A key benefit is their anti-inflammatory properties which have been proven to reduce levels of chronic inflammation in the body.⁸
• The main anti-inflammatory molecules in an apple are: polyphenols, pectin, and ascorbic acid (vitamin C)
• The consumption of these molecules both prevents and reduces the levels of chronic inflammation and therefore protects you against the development of many chronic diseases.²

We recommend the consumption of two fresh raw apples a day. It is important to consume them with the skin on them as this is where the majority of the anti-inflammatory compounds are found.¹²