Lemon Flavonoids
Lemons have some flavonoid antioxidants in common with other citrus fruits. They also have many unique flavonoids that are not found in any other citrus fruit (1,3). The flavonoids in lemon have a moderate to strong antioxidant ability (1). Around 90% of the flavonoids in lemons are from a sub-class of flavonoids known as flavanones (2). Almost all of the flavanones found in the human diet are from citrus fruits (3), so lemons represent an important dietary source of flavonone antioxidants.
Heart Disease
Spanish researchers conducted a clinical trial in 2011 that demonstrated that a lemon juice beverage decreases several heart disease risk factors (4). Fifty-three middle-aged (50-65 years old) adults participated in the trial: 20 healthy participants and 33 participants with metabolic syndrome. Individuals with metabolic syndrome have an increased risk of heart disease due to several factors. These include high levels of C-Reactive Protein (CRP), which indicates the presence of chronic inflammation in the body, and increased oxidation of LDL (bad) cholesterol (4). For six months, each day participants drank either 300 mL of lemon juice and chokeberry mixture containing 95% lemon juice, or 300 mL of a placebo beverage. After 6 months, the amount of CRP and oxidized LDL cholesterol was significantly lowered in the participants with metabolic syndrome that drank the lemon juice beverage, compared with those that drank the placebo beverage. Levels of homocysteine, an amino acid that is associated with increased heart disease, were also significantly lowered in metabolic syndrome participants that received the lemon juice beverage.
Cancer
More research is needed to better understand the role that lemons play in cancer prevention, but some recent studies have demonstrated positive results. For example, one cell culture study found that lemon extract helps to prevent breast cancer cells from spreading (5). This was accomplished by causing a type of programmed cell death known as apoptosis (5), a process that is normally impaired in cancer cells. As well, a comparison of 11 studies conducted in various countries across the world found that in general, higher citrus intake was associated with lower risk of developing pancreatic cancer (6).
Digestion
Another benefit of lemons is that they improve digestion. As lemon juice enters the mouth, it causes an increase in saliva production (7), which is one of the first steps involved in digestion. Aromatic compounds in the lemon rind can also increase saliva production (7). This increase in saliva production then influences digestion in the stomach as well (7). Specifically, there is an increase in the amount of the digestive enzyme pepsinogen, which breaks down protein, and stomach acid that is released by the stomach (7). In addition, the acid in lemon juice has been found to increase pancreatic secretions (7), which help to break down and absorb fats in your diet.
