Lactose and maltose are both carbohydrates, a category of nutrient that provides your cells with energy, and includes table sugar and starch. While lactose comes primarily from dairy, maltose is found in starchy foods, such as bread and spaghetti. Some individuals don't produce the lactase enzyme, which breaks down lactose, and consequently have lactose intolerance.
Lactose
The lactose molecule, in addition to being a carbohydrate, meaning it's made up of carbon, hydrogen, and oxygen, is also a disaccharide. This means that lactose consists of two smaller sugar units -- monosaccharides -- explain Reginald Garrett, Ph.D., and Charles Grisham, Ph.D., in their book "Biochemistry." The smaller units that compose lactose are glucose and galactose; when you eat lactose, you break it down into these smaller sugar units and absorb them.
Maltose
Like lactose, maltose is a disaccharide. It's made up of two glucose molecules, making it very similar in composition to starch, which is made of nothing but glucose. While maltose contains only two glucose units, however, starch contains hundreds. When you eat maltose, you break it down into pure glucose and absorb the glucose units into the bloodstream, explain Mary Campbell, Ph.D., and Shawn Farrell, Ph.D., in their book "Biochemistry."
Uses of Maltose and Lactose
While you can't use either maltose or lactose directly -- you have to digest them both into their smaller sugar units -- you can use the units you obtain from these sugars in nearly identical ways. Your cells can burn both glucose and galactose for immediate energy, and can also use either of them to make glycogen, a carbohydrate stored by the liver and muscles. You can also convert them to fat and store them.
Deficiencies
Lactose intolerance -- an underproduction of the enzyme that breaks down lactose -- is relatively common. If you're lactose intolerant, you experience symptoms of gastric distress upon consuming lactose. Typically, lactose intolerance is more common as you age and your body stops producing as much of the enzyme. Deficiencies in children are exceedingly rare. It's even more rare to be deficient in the enzyme that digests maltose -- sucrase isomaltase -- explains the Genetics Home Reference.
References
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- "Biochemistry"; Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005
- Genetics Home Reference: Sucrase Deficiency
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