is the process by which the body breaks down food into absorbable
nutrients. The body absorbs and assimilates everything that we ingest.
Digestion includes physical actions such as chewing and peristalsis
(involuntary contraction and dilation of muscles to force forward
movement), as well as the chemical actions of enzymes, bile and acids.
enzyme is a protein that acts as a catalyst in a biological reaction.
It binds itself to a substance and converts it into another substance.
Enzymes are very specific in their functions, which is why there are
different enzymes for different biological reactions. In the case of
digestion, distinct forms of food require specific enzymes. Food is
digested in three areas of the body: the mouth, the stomach and the
in the mouth with chewing, food is physically broken up into small
pieces to facilitate the beginning of complete digestion. Chewing
thoroughly is an important step because smaller pieces offer more
surface area for contact with the digestive enzymes and acids in the
stomach and are therefore more easily digested. Chewing also
stimulates the release of hormones that control appetite. The longer
you chew, the less likely you are to overeat.
one digestive enzyme, amylase (for starch), is present in the
mouth. However, food is normally not in the mouth long enough to
permit complete digestion and little nutrient absorption takes place
in the mouth.
primary function of the stomach is to break large proteins into
smaller peptides and peptones. The acidic environment in the stomach
(1.5 to 7.0 pH) is home to the enzyme pepsin, used to digest
proteins. Pepsin breaks up proteins into smaller peptides of
varying lengths. Other enzymes such as gelatinase (for gelatin)
digest specific proteins.
(for starch) is inactivated, or destroyed, when stomach pH falls below
Before this happens however, up to 50% of starches may be partially
broken down. Some fat is emulsified (broken up into smaller pieces) in
the stomach by bile acids, and the enzyme lipase, to aid digestion in
the small intestine. At the average stomach pH of 2.0, however, most
fat is formed into large globules that pass unchanged into the small
intestine. Small amounts of sucrose (table sugar) may be broken apart
into glucose and fructose by acid hydrolysis from the bile acids in
all absorption of nutrients (macronutrients such as carbohydrates and
fats and micronutrients such as vitamins and minerals) occurs in the
intestines. Absorption of nutrients is, in fact, the primary function
of the small intestine. Most carbohydrates, for instance, are absorbed
in the small intestine. The pancreatic enzymes secreted into
the small intestine also contain amylase which breaks down
starches into a disaccharide (a complex carbohydrate) called maltose.2
In the intestines, enzymes such as maltase and lactase
break disaccharides into single sugars, such as glucose. When adults
and older children do not have enough lactase to digest lactose
(the sugar in milk) lactose intolerance results and milk cannot
be completely digested.
food leaves the stomach, digestion is completed in the small intestine
with the help of the enzymes secreted by the pancreas (lipase,
amylase, protease, maltase, trypsin and chymotrypsin). The pH of food
mass increases from about 2.0 to 6.5 (still slightly acidic), as it
passes from the stomach through the small intestine to the colon. Very
few nutrients, except water, is absorbed by the large intestine
is the most important macro nutrient we consume. Over 50% of our body
weight is water. Beverages provide just under half of the water we
require each day. The rest of the water is from food. Water also aids
digestion as part of the food mass in the intestines. Motility, the
movement of food in the digestive tract, is more effective if more
water is retained in the food. When food reaches the colon, most of
the water is reabsorbed.
occurs primarily in the small intestine. Most carbohydrates are easily
digested and 90% to 98% are absorbed.1 Bile acids in the
stomach aid in acid hydrolysis to break sucrose down into glucose and
fructose. Before the stomach pH falls below 6.5, destroying amylase,
up to 50% of starches may be partially broken down, but digestion of
most carbohydrates is done in the small intestine.1
a complex carbohydrate, makes up the remaining 2% to 10% of unabsorbed
carbohydrates. Dietary fiber can be further subdivided into soluble
and insoluble fibers.1
Insoluble fibers (such as lignins and cellulose from
vegetables, grains and nuts) increase fecal bulk and decrease transit
time through the intestines.3
They are partially digested by intestinal bacteria but are not
absorbed well. Soluble fibers (such as pectins and gums from
fruits, beans and grains) delay stomach emptying, slow the absorption
rate of glucose and help to lower the levels of fats and cholesterol
in the blood.4 Pectins are neither digested nor absorbed, but gums
may be partially digested by intestinal bacteria and absorbed1
providing food for the cells lining the colon.
(or lipids) such as those found in egg yolks, can be broken into
glycerol and fatty acids by stomach acids, but most fat digestion
occurs in the small intestine. Bile, secreted by the gall
bladder, emulsifies large fat particles and breaks them into a smaller
size so that pancreatic and intestinal lipases can digest the
fats. The lipase enzymes are responsible for the majority of fat
digestion. Fats are 95% to 100% digestible in healthy people.1
Bile salts also facilitate absorption of fatty acids.
starts with stomach enzymes (proteases) such as pepsin
that break apart specific links in the amino acid chains that
comprise proteins. These chains are reduced to much shorter lengths,
called peptides and peptones. The partially digested proteins move
onto the small intestine where pancreatic protease continues
digestion, breaking the peptides and peptones into individual amino
acids which are absorbed directly or attached (chelated) to minerals,
thus allowing mineral absorption.
digestibility varies widely 1:
vegetables and fruits: 65% to 85%
cereals and grains: 76% to 84%
milk, meat and eggs: 97%
protein digestion is incomplete, longer peptide chains of undigested
proteins can be absorbed, possibly causing allergic reactions.5
Symptoms of food allergies vary widely and can affect any part of the
and PROBIOTICS such as Lactobacillus acidophilus also are
important digestive aids and sources of nutrition. Intestinal
bacteria synthesize biotin and vitamin K, both essential nutrients.5
Lactobacillus acidophilus and other friendly intestinal bacteria
can help the intestines maintain a healthy colon against an onslaught of
unhealthy pathogenic bacteria such as E. coli or salmonella,
especially in infants.6
These friendly probiotic bacteria also help the digestion of
proteins, carbohydrates and fats.6, 7 Probiotics
(or “friendly” bacteria) can be found naturally in the body, but the
majority are ingested in foods or as supplements.
digestion of foods and the absorption of nutrients is the first, and
most important, step to good health. Our bodies are designed to get the
highest possible benefit from food, but digestive aids are sometimes
needed. Many of us also supplement our diet to ensure we obtain adequate
nutrition. The proper absorption of dietary supplements is just as
important as the proper digestion of food, and the two work closely
Life digestive aids and enzymes can be the answer for those who have
trouble digesting foods, or those who merely want to insure optimal
nutrient absorption. Remember,
eat a healthy balanced diet, chew your food thoroughly, drink plenty of
water and take Nature’s Life Digestive Aids for nutritional insurance.
J.A., Ph.D. Introductory Nutrition, The C.V. Mosby Company, St
R.L., Ph.D. & Brown, M.L., Ph.D., Nutrition: An Integrated
Approach, John Wiley & Sons, Inc. New York;1975
K.E.B., et al. Physiological Implications of Wheat and Oat Dietary
Fibers in New Developments in Dietary Fiber, 1990; Advances in
Experimental Medicine and Biology, 1990;270:135-147.
J.W. and Ward, K. High carbohydrate, high fiber diets for
Insulin-treated men with diabetes mellitus. American Journal of
Clinical Nutrition, 1979;32-2312.
D.A. M.D., Clouse, R.E., M.D. & Stenson, W.F., M.D. Manual of
Nutritional Therapeutics, Little Brown & Company, 1984.
B.A. et al. Nutritional and Therapeutic Aspects of Lactobacilli. Journal
of Applied Nutrition, 1984;36(2):125-153.
C.F., et al. Therapeutic role of dietary Lactobacilli and
Lactobacillus fermented dairy products. Fed of Eur Microbiol Rev,