A Look at Lactose Intolerance
Lactose is the primary carbohydrate in milk. Cow's milk
contains 4-5% lactose, whereas human milk contains
almost twice that amount. Lactose provides 30-50% of the
energy in milk, depending on the fat content (skim vs.
A number of individuals are affected by lactose in the diet,
but there is a difference between intolerance and
Lactose maldigestion is "a disorder characterized by
reduced digestion of lactose due to the low availability of the
enzyme lactase." Lactose intolerance is "the term for
gastointestinal symptoms (flatulence, bloating, abdominal
pain, diarrhea, and 'rumbling in the bowel') resulting from
the consumption of more lactose than can be digested with
available lactase." In other words, intolerance refers to the
symptoms of the maldigestive disorder caused by an
insufficient enzyme required to hydrolyze lactose to
galactose and glucose.
Genetic defects often cause a deficiency of lactase, as well
as injuries to the mucosa lining of the intestines or with age
(as we age our enzyme levels decrease). When lactose
molecules remain in the intestine undigested, they absorb
water and this can cause bloating, discomfort, cramping,
diarrhea, and nausea. Bacterial fermentation along the
intestinal tract that produces lactic acid and gas is also a
characteristic of lactose intolerance.
It is estimated that one in three adults suffer from lactose
maldigestion and it appears to be inherited in about 80% of
the world's population, including most Greeks, Asians, and
Those who suffer from any discomfort after eating or
drinking milk products can consume foods labeled lactose
free or take an enzyme preparation such as Lact-Aid to aid
digestion. Do note, however, that lactose intolerance varies
and the amount of lactose allowed in a diet depends on an
individual's tolerance. Some people cannot tolerate milk,
ice cream, or creamed foods, but they can eat aged
cheeses and yogurt (some brands are better tolerated than
others) without difficulty. Lactose products include:
Grain Products: Breads and muffins made with milk,
pancakes, and waffles; cake or cookie mixes, pie crusts
made from butter or margarine, French toast, some dry
cereals, and biscuits.
Fruits and Vegetables: Canned and frozen fruits or
vegetables processed with lactose, buttered, creamed, or
Milk and Milk Products: Milk (dried, evaporated, nonfat, and
whole), yogurt, ice cream, sherbet, cheese, custard,
puddings, and whey and casein proteins manufactured with
Meat and Meat Alternatives: Meats, fish, or poultry creamed
or breaded, sausage and other cold cuts containing
nonfat-milk solids, some peanut butter, and omelets and
soufflés containing milk.
Other: Instant coffees, margarine, dressings, sugar
substitutes containing lactose, toffee, chocolate, creamed
soups, butter, cream, some cocoas, caramels, chewing
gum, some vitamin-mineral supplements, some drugs,
peppermint, and butterscotch.
Since calcium is a major component of many
lactose-containing foods, it is vital that individuals who are
lactose-intolerant receive adequate calcium from other
foods (in fact, milk is not an ideal source of calcium, as will
be discussed in Chapter Seven). These include almonds,
brazil nuts, caviar, kelp, canned salmon, canned sardines,
shrimp, soybeans, and turnip greens, broccoli,
strawberries, and leafy greens. Leafy greens are currently
under suspicion as a viable calcium source since greens
are now believed to contain certain calcium binding agents
that prevent calcium absorption.
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Brian D. Johnston is the Director of Education and President
of the I.A.R.T. fitness certification and education institute. He
has written over 12 books and is a contributing author to the
Merck Medical Manual. An international lecturer, Mr.
Johnston wears many hats in the fitness and health
industries, and can be reached at
info@ExerciseCertification.com. Visit his site at
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