Lemons contain fructose, a natural sugar common to most fruits. However, compared to many other fruits, lemons contain relatively low amounts of fructose. High levels of fructose can cause irritation in the bowel and intestines. As of 2011, several studies point to negative effects of fructose, though overall evidence is inconclusive. Despite the issues with fructose, lemons are a good source of nutrition.
Fructose is a simple sugar, or monosaccharide, found in fruit, some vegetables and natural substances such as honey. Fructose occurs in different concentrations in fruit. Lemons contain low doses. Fructose joins together with glucose, another monosaccharide to make the disaccharide sucrose, or table sugar. Unlike glucose, your body cells don't use fructose directly. Instead, the liver breaks down fructose into different chemicals.
Lemons and Sugars
Around 2.5 percent of every lemon is made up of sugars. That means a medium lemon of 2-1/8-inch diameter contains 1.45 g of sugar, according to the USDA Nutrient Database. Fructose makes up much of this total. However, according to the University of Virginia Digestive Health Center, lemons and other acid fruits, such as limes, contain some of the lowest fructose levels of all fruits. The university's site lists lemons as "intestine friendly" for people sensitive to fructose in their diets.
Low Fructose Diet
According to UCSF pediatric neuroendocrinologist Robert Lustig, fructose may have a negative impact on health. The liver converts fructose in part into triglycerides, as well as uric acid and free radicals. All of these can cause harm in the body. Triglycerides can cause heart disease and obesity. Free radicals attack healthy cells. Uric acid is a toxin that the body needs to remove. For these reasons, many people follow a low fructose diet. Lemons, as a low fructose fruit, may feature in this diet.
Neither kids nor adults usually choose to have a glass of lemon juice to quench their thirst. The sourness of the juice makes it more suitable for squeezing into dishes during cooking or adding a small amount to smoothies. This means that even if lemons contained more fructose, you would be unlikely to consume too much of it anyway. If you're worried about your fructose intake, the fructose in lemons shouldn't be high on your list of dietary concerns.