It is a monosaccharide component of sucrose present in fruits as fruit
sugar (laevulose). It is used in beverages, fruit juices, pulps.
Fructose is also found in ‘table sugar.’
It provides similar amount of energy as sucrose. Fructose is termed a
‘slow sugar’ as it is metabolized slower than sucrose. In a
well-controlled diabetic, the fructose metabolic pathway demonstrates a
positive flux towards formation of glycogen from fructose i.e.
glycogenesis.
Sources of dietary fructose include agave, the richest natural source of
fructose, with 85% of carbohydrate in this form; honey, with
approximately 50%; and fruit juices.
Fructose is very sweet and is often made into high fructose corn syrup,
used in soft drinks and processed foods. HFCS is made from acid- or
amylase-treated corn starch and contains 42–55% fructose. The most
popular HFCS formulations used for food applications are the HFCS-42 and
HFCS-55. HFCS-55 consists of ~55% fructose and ~45% glucose. HFCS-55
is mainly found in soft drinks and other sweetened beverages.
A 16-ounce bottle of apple juice may have more than 30 grams of fructose
and a 20-ounce bottle of soda can have up to 40 grams.
Fructose is associated in epidemiologic studies with greater weight,
triglyceride, blood pressure, and insulin resistance levels and in
animal and human feeding studies with small dense LDL cholesterol,
nonalcoholic fatty liver disease, and greater levels of protein
glycation. An increased intake of fructose may cause
hypertriglyceridemia, especially in patients with uncontrolled
diabetes.
Hereditary fructose intolerance is a very rare genetic disorder. This is
when the liver is not able to help the body break down fructose.
Symptoms can be more serious. This disorder requires more than just
limiting fructose.