This is a course that covers fundamental concepts and theories of the life sciences.
Topics include cell morphology and physiology, metabolism, genetics, evolution, ecology, and reproduction. Enrichment activities
and discussions will reinforce and enhance understanding of lecture topics. Organisms of all five kingdoms will be studied,
but emphasis will be placed on plants and animals.
At the end of the term, the student should be able to:
Enhance his understanding of cellular structure and function as well as the chemistry and homeostatic mechanisms of cell
Develop an understanding of life at all levels of organization.
Acquire an understanding of the interdependence that characterizes natural communities and evolutionary relationships
that unite all living things.
Be familiar with current developments in the life sciences by reading and reporting on articles that are of relevance
to the field.
Introduction to Biological Science
Related Disciplines and Approaches
Significance of studying Biology
Characteristics of Life
Irritability or Response to Stimuli
Chemical Basis of Life
Some Basic Chemistry Facts
Vitamins and Minerals
Cellular Basis of Life
Parts and Functions of Cells
Differences between plant and animal Cells
Cellular reproduction (Mitosis and Meiosis)
Classification and Nomenclature
History of Taxonomy
Organ Systems (emphasis on man)
Introduction to Evolution
History of Evolution
Evolution Theories and Principles
Introduction to Ecology
History of Ecology and Environmental Studies
Ecology in the Philippine setting
Medicine, Bio Issues and Recent Medical Breakthroughs
History of Medicine
Human Genome Project
I. Introduction to Biological Science
Identify the several definitions of biology;
Compare and contrast the varied fields of study that are related to biological science.
Trace the development and progress of biology in the world;
Explain how scientists use the scientific method, how he generate observations, formulate and test hypothesis and make
Appreciate the value of biological study in your life.
The word biology is formed by combining the Greek βίος (bios), meaning "life", and the suffix '-logy', meaning "science of", "knowledge of", "study of",
based on the Greek verb λεγειν, 'legein' = "to select", "to gather" (cf. the noun λόγος,
'logos' = "word"). The term "biology" in its modern sense appears to have been introduced independently by :
The word itself appears in the title of Volume 3 of Michael Christoph Hanov's Philosophiae naturalis sive physicae dogmaticae: Geologia, biologia, phytologia generalis et dendrologia, published
science of life
study of structures, functions and relationships of living things or organisms
realm of life
a science that is linked to other sciences
all processes associated with living organisms are the subject matter
study of living things
trascends such sciences as chemistry, physics, mathematics and geology
field where all the sciences meet the social domains and the humanities such as economics, politics and environmental
ethics due to man’s interaction with his environment
draws on chemistry and physics for its foundation and applies these basic physical laws to living things
begins with a search for answers to questions about our world
As early as between 3000 and 2000 BC, major civilizations of China, Egypt, and India had knowledge of certain biological
processes, primarily with the practical aspects of agriculture and medicine.
During the Renaissance era (1300-1650 AD), serious study of anatomy emerged through the efforts of Leonardo da Vinci and
In 1750’s, a major advance in Biology was the publication of Carolus Linnaeus’ classification scheme for organisms
In 1859, Charles Darwin published his theory of evolution in a book entitled “On the Origin of Species by Means
of Natural Selection”.
In 1865, Gregor Mendel published evidence that garden peas inherited characteristics from their parents (introducing fundamental
Mapping, or more properly, assignment of human genes to locations on various chromosomes proceeded when Mohr noted
in 1951 that a gene for a blood protein factor, Lutheran, in some families appeared to be associated with another gene controlling
salivary secretion of a red blood cell protein. In other families it was not associated with the secretion gene. Thus "secretor"
and Lutheran appeared linked and presumably close together on the same chromosome. Both of these are now assigned to Chromosome
19, physically corroborating the earlier family linkage studies of Mohr.
The major contribution of Watson and Crick came in 1953, the description of the molecular structure of the genetic material,
the double helix.
Tijo and Levan in 1956 found human beings had 46 and not 48 chromosomes, and several years later, Lejeune noted a 47th
chromosome in individuals with Down syndrome.
By 1995, the entire 1,830,137 base pairs of the bacterium, Haemophilus influenzae , had been sequenced and its genes mapped
by a large team headed by J. Craig Venter at the Institute for Genomic Research (TIGR) in Gaithersburg, MD (Venter, 1995).
It has served as a superb model for how an animal's genome programs itself from a single fertilized cell into a multi-celled
c. 350 B.C. - Aristotle attempted a comprehensive classification of animals. His written works include Historia Animalium, a general biology of animals, De Partibus Animalium,
a comparative anatomy and physiology of animals, and De Generatione Animalium, on developmental biology.
1802 - The term biology in its modern sense is propounded independently by Gottfried Reinhold Treviranus (Biologie oder
Philosophie der lebenden Natur) and Lamarck (Hydrogéologie). The word had been coined in 1800 by Karl Friedrich
Biological Psychology: use of biology in psychological studies
Biomathematics: use of math in the study of living things
Biophysics: use of physics in the study of living things
Physiology:Greekphysis = nature and logos = word) is the study of the mechanical, physical, and biochemical functions of living
Biochemistry: use of chemistry in the study of living things
Anatomy: study of internal structures of living things
Pathology: study of diseases (particularly animal diseases)
Phytopathology: study of plant diseases
Taxonomy: study of systematic classification
Ecology: study of man’s interaction with his environment
Genetics: study of heredity
Microbiology: study of microorganisms
Bacteriology: study of bacteria
Virology: study of viruses
Mammalogy: study of mammals
Ornithology: study of birds
Herpetology: study of reptiles and amphibians
Ichthyology: study of fishes
Entomology: study of insects
Helminthology: study of worms
Protozoology: study of unicellular organisms
Mycology: study of fungi
Phycology/ Algology: study of algae
Lichenology: study of lichens
Biosociology: the study of the evolution of social forms and the development of social behavior in terms analogous
to or correlated with biological studies.
Parasitology: study of parasites
Epidemiology: study of epidemics
Gnotobiotics: study of organisms in a germ-free environment
Biogeography: study of geographical distribution of living things
Phytogeography: study of the land and its plants
Zoogeography: study of the land and its animals
Biological limnology: the scientific study of bodies of fresh water, as lakes and ponds, with reference to their
physical, geographical, biological, and other features.
Embryology: study of the formation and development of living things from fertilization to birth as independent
Pharmacology: study of the actions of chemicals on and in living things
Endocrinology: study of hormones and their actions
Cytology: study of cells
Histology: study of tissues
Bryology: study of mosses
Malacology: study of mollusks
Physical Sciences (concerned mainly with the nature of the universe)
Astronomy: the science that deals with the material universe beyond the earth's atmosphere
Chemistry: the science that deals with the composition and properties of substances and various elementary forms
Geology: science of the earth's history, composition, and structure, and the associated processes.
Meteorology: branch of science that deals with the atmosphere of a planet, particularly that of the earth, the most important application of which is the analysis and prediction of weather.
Climatology: the science that deals with the phenomena of climates or climatic conditions
Physics: branch of science traditionally defined as the study of matter, energy, and the relation between them
Social Sciences (concerned with the study of man and society)
Anthropology: classification and analysis of humans and their society, descriptively, culturally, historically,
2. Geography: the science of place, i.e., the study of the surface of the earth, the location and distribution of
its physical and cultural features, the aerial patterns or places that they form, and the interrelation of these features
as they affect humans
3. Physiogeography: the systematic description of nature in general.
4. Oceanography: the systematic description of sea animals in oceans.
Biogeography: the systematic description of animals abundant in the air
Linguistics of Philology: systematic study of similarities and differences of languages
Political Science: study of the nature and existence of governments
Significance of studying Biology
A good grasp of the biological perspective and the development of appreciation on how
biological knowledge works on one’s life are important elements of good citizenship especially in an era when issues
on environmental problems, health conditions and biotechnology are more crucial than ever. Let us identify some of the usefulness
of biology in your life.
You possess all the manifestations of being alive and of living with other forms. A study of biology enables you to understand
and value your place in the earth’s environment as well as your relationship with other life forms.
As a conscious being, you are confronted with making choices on how to sustain your own life and health. Biology helps
you understand the basic mechanisms of bodily processes; hence, it enables you to make choices and decisions for yourself
as a food and medical consumer, as well as energy user.
You live in an era of critical issues like abortion, human life preservation over population explosion, drug addiction
and environmental degradation. Your knowledge of biology will enable you to form learned opinions and scientifically guided
decisions and actions on such issues.
You live in an era of escalating dimensions of science and technology. Knowledge of significant developments in biology
and biotechnology will eliminate confusing and threatening views bothering your mind and help you develop positive approaches.
A solid foundation in biological science is necessity for your future life as a life partner and parent, as well as a
professional in any field. A scientifically literate person progresses in his practices, beliefs and attitudes in life. (Hafalla,
Recognize something has happened and that it occurs repeatedly. (empirical evidence is gained from experience or observation)
Students in a classroom are stricken with a disease that causes red rashes on their faces. This same situation has been
described in several schools in your region. Skin cultures taken from the students indicate that there are some unusual bacteria
Write many different kinds of questions about the observation, evaluate the questions and keep the ones that will be answerable.
Is the disease psychosomatic? (i.e., is this a case of hysteria in which there is nothing organically wrong?)
Is the rash caused by a bacterium?
Is the disease caused by a virus?
Exploration of alternative resources
Go to the library to obtain information about this observation. Also, talk to others who are interested in the same problem.
Visits to other researchers or communication via letter, fax or computer will help determine if your question is a good one
or if others have already explored the topic.
A search through the medical literature reveals that physicians who used antibiotic X in similar circumstances reported
cures, even though they never found a bacterium to be present. Attend scientific meetings where this disease outbreak will
be discussed. Contact scientists who are reported to be interested in the same problem.
Pose a possible answer to your question. Be sure that it is testable and that it accounts for all the known information.
Recognize that your hypothesis may be wrong.
Antibiotics do not usually affect viruses. Further, the disease has been reported elsewhere, which tends to rule out psychosomatic
disease. Therefore, your hypothesis is that the disease is caused by a bacterium and that antibiotic X can cure the disease
by controlling the rate of growth of the bacterial population.
Set up an experiment that will allow you to test your hypothesis using a control group and an experimental group. Be sure
to collect and analyze the data carefully.
To test the cause-and-effect relationship between administering antibiotic X and curing the illness, you set up 2 groups.
A control group will be given a placebo (a pill with no active ingredient). The experimental group will receive pills containing
antibiotic X. The pills will look identical and will be coded so that neither the person receiving the pill nor the person
administering the pill will know which individuals receive the medication and which receive the placebo. This is called a
“double-blind” test. After five days, you collect the data and find that 90% of those receiving antibiotic X no
longer have the rash. By contrast, only 10% of those receiving the placebo have recovered. You conclude that the disease is
not psychosomatic and that a bacterium is probably the cause. You publish your results.
Repeat the experiment and share the information with others over a long period of time.
Your results support the generally held theory that many kinds of diseases are caused by microorganisms.
This generalization is called the germ theory of disease.
If your findings are seen to fit with many other major blocks of information that tie together many different kinds of
scientific information, they will be recognized by the scientific community as being consistent with current scientific laws.
If there is a major new finding, a new law may be formulated.
Your experimental results are consistent with the biogenetic law that states that all living things come from previously
living things. Your results strongly suggest that the disease was caused by the multiplication of certain bacteria, and that
the antibiotic stopped their multiplication.
tips, facts, news you can use
Cell phone “shields” useless, says US agency
Not only do some of the commercially available shields that claim to protect users
from cells phone radiation not work as promised, they in fact, may cause the phone to emit even more energy. The US Federal
Trade Commission (FTC) has filed charges against the makers of two such devices, saying the only “shield” at work
is one of misrepresentation to consumers about the products’ effectiveness, the Associated Press reports. The two companies
named in the lawsuits are Stock Value 1 Inc., of Boca Raton, Florida and Comstar Communications Inc., of West Sacramento,
California. The FTC says both companies made false claims about scientific tests about their products, and it hopes to close
both down once customers are given refunds. In fact, says the FTC, there are no known products that reduce cell phone radiation
exposure to users. The coin- sized devices are designed to cover phone earpieces and were sold for about $20 each.
Source: Health Today, June 2002 Edition
How much have you learned?
Enrichment activities, exercises to keep you on your toes…
Cite 3 definitions of biological science. Why is it significant to include it in your curriculum?
Analyze the timeline of biology presented and discussed previously. What do you think are the five (5) major inventions
or discoveries of all time? Prove your point.
Name five (5) approaches/disciplines that are related to biology and make connections why you consider them as related
Activity: Scientific Investigation
Concept: The Power of Observing and Hypothesizing
1. Recognize the steps in scientific investigations
Formulate a problem and hypothesis for scientific investigation
Draw procedures applicable to the problem and the hypothesis.
pair of scissors
Form groups of five students and arrange chairs in a circular fashion to facilitate the discussion.
Scan the pages of the magazine. Choose a picture on environmental changes or technological trends and the like that attracts
Cut and paste the picture/s on the clean bond paper.
List some observed situations and scenes. (Note: record observations but not perceptions)
Analyze the situations or scenes shown in the picture.
Formulate scientific problem that can be tested based on the observed situations.
The following activities can help you in the formulation of the problem:
Brainstorming of ideas and topic related to the situations;
Listing down some related situations that are actually happening in life;
Narrowing the problems into specific ones.
Formulate a hypothesis that will serve as the temporary answer or solution to the problem.
Conceptualize the procedure to determine if your hypothesis can be tested or not.
Make generalization on how problems and hypotheses are formulated.
Submit output 15-20 minutes before the end of the class hour for critiquing and evaluation.
II. Characteristics of Life
Discuss the attributes of manifestations of the living state;
Infer what life is from the manifestations of the living state.
Analyze some significant biological principles and concepts, which form basic conclusions about living things.
Living things are made of cells, which are assembled into interrelated system for performing
the life processes. They rearrange and combine the chemical elements for their need. Non-living things on the other hand cannot
recombine materials and their structure depends on chemicals present and mode of formation (Ditan, p.1 )
Metabolic processes involve the total of all chemical reactions and associated
energy changes that take place within an organism. This set of reactions is often simply referred to as metabolism (=Greek
metaballein, to turn about, change, alter). There are three essential aspects of metabolism: (1) nutrient uptake (2) nutrient
processing, and (3) waste elimination. (Ross, p.11).
Two phases of metabolism:
anabolism: constructive or building up phase
Catabolism- destructive or breaking down phase.
Irritability or Response to Stimuli
Irritability is an excessive response to stimuli. Irritability takes many forms, from the contraction of a unicellular organism when touched to complex reactions involving all the senses of higher animals. In plants response is usually different from that found in animals but is nonetheless present. The term irritability is both used for
the physiological reaction to stimuli and for the pathological, abnormal or excessive sensitivity to stimuli.
Biological reproduction is the biological process by which new individual organisms are produced. Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction by an antecedent. The known methods of reproduction are broadly
grouped into two main types: sexual and asexual reproduction.
In asexual reproduction, an individual can reproduce without involvement with another
individual of that species. The division of a bacterial cell into two daughter cells is an example of asexual reproduction. Asexual reproduction is not, however, limited to single-celled organisms. Most plants have the ability to reproduce asexually.
Sexual reproduction requires the involvement of two individuals, typically one of each
sex. Normal human reproduction is a common example of sexual reproduction. In general, more-complex organisms reproduce sexually
while simpler, usually unicellular, organisms reproduce asexually.
A biologicaladaptation is an anatomical structure, physiological process or behavioral trait of an organism that has evolved over a period of time by the process of natural selection such that it increases the expected long-term reproductive success of the organism. The term adaptation is also sometimes used as a synonym for natural selection, but most biologists discourage this
Adaptation can be viewed as taking place over geological time, or within the lifetime of one individual or a group.
Organisms that are adapted to their environment are able to:
get air, water, food and nutrients
cope with physical conditions such as temperature, light and heat
defend themselves from their natural enemies
respond to changes around them
Adaptations are the way living organisms cope with environmental stresses and pressures. One common form
of physical Adaptation involves acclimatization. Acclimatization allows the organism to be able to exist in its new environment. Adaptation can be structural or behavioural.
Structural adaptations are special body parts of an organism that help it to survive in its natural habitat, for example,
its skin color, shape and body covering. Behavioral adaptations are special ways a particular organism behaves to survive
in its natural habitat. Organisms that are not suitably adapted to their environment will either have to move out of
the habitat or die out. The term die out in the context of adaptation simply means a specieces' death rate excedes
its' birth rate for a long enough period for the species to disappear.
It is possible for an adaptation to be poorly selected or become less appropriate or even become on balance
more of a dysfunction than a positive adaptation over time; this is known as maladaptation and can apply to both humans and animals in such fields as biology, psychology (where it applies to behaviors and other learned survival mechanisms) and other fields.
There is a great difference between adaptation and acclimation. Adaptation occurs over many generations; it is generally a slow process caused by natural selection. Acclimation occurs
generally in a single lifetime and copes with issues that are less threatening. For example, if a human was to move to a higher
altitude, respiration and physical exertion would become a problem, but after spending a duration of time in high altitude
conditions one will soon acclimate to the pressure and function and no longer notice the change.
tips, facts, news you can use
Your Faith Will Heal You…
Participants of “Spirituality and Healing in Medicine”, a seminar held
at Harvard University six years ago, declared that “prayer… could have astounding therapeutic effects.”
“I am not a religious person,” said Dr. Herbert Benson, a Harvard Medical
School cardiologist and founder of the Mind-Body Institute at Beth Israel Deaconess Hospital. But study after study convinced
him that prayer was good for his patients. His research showed that:
Two 10-minute prayer sessions per day could lower the heart rate, slow down breathing, and stabilize brain wave activity
Prayer could avert the need for invasive surgery and substantially reduce the need for visits to a doctor.
Thirty-five percent of couples with fertility problems with in six months of beginning prayer sessions.
Source: Health Today, June 2002 Edition
Lydia Strohl and Elena Serocki, citing results of hundreds of studies, revealed that
people with strong religious faiths and prayed regularly:
have longer lives
have fewer health problems
have three times better chance of surviving open-heart surgery
are 70% less prone to coronary heart disease
have lower rates of depression and anxiety
Source: “The Healing Power of Faith”, Readers Digest September 2002
How much have you learned?
Enrichment activities, exercises to keep you on your toes…
Formulate a concept map indicating all the manifestations of the living state how these are interrelated and what principles
How can you operationally define “life”?
Discuss the differences of the form and structure between plants and animals.
Life is a fragile state totally dependent on its environment. How committed are you
in conserving the Earth’s resources that sustain life?
III. Chemical Basis of Life
Define basic terms in the study of the chemical basis of the living state.
Compare and contrast organic from inorganic compounds.
Discuss the vast uses and potentials of vitamins, minerals and water.
Some Basic Chemistry Facts
Chemistry: science that is concerned with matter, its composition, its properties, the changes in composition that
it will undergo, its relationship to energy, and the laws, principles, theories, and concepts that describe, interpret, and
predict its behavior and basic nature
Matter: anything that has mass and occupies space
Composition: refers to what matter is made of
Properties: characteristics that identify substances
Physical properties: can be observed or measured without changing the composition of the substance
Chemical properties: can be observed or measured only when it undergoes a change in composition
Chemical changes: changes in the composition of substances
Chemical reaction: the process of chemical change
Fact: a piece of information about nature that is based on observation, often a measurement that can be repeated
Law: a general statement that sums up a number of facts
Organic Compounds: compounds that contain carbon (and usually hydrogen and oxygen)
Inorganic Compounds: compounds that do not contain carbon (except carbon dioxide and carbon monoxide)
Vitamins: organic nutrients that are necessary in small amounts for normal metabolism and good health
Water: from the Old Englishwaeter; c.f German "Wasser", from PIE*wod-or, "water"), in its pure form, is a tasteless, odorless substance that is essential to all known forms of life and is known also as the most universal solvent. It appears colorless to the naked eye in small quantities, though it can be seen to be blue in large quantities or with scientific instruments
a. Carbohydrates: group of chemicals that include sugars, starches and cellulose.
Carbohydrates are the main energy source for the human body. Chemically, carbohydrates are organic molecules in which carbon, hydrogen and oxygen bond together in the ratio: Cx(H2O)y where x and y
are whole numbers that differ depending on the specific carbohydrate to which we are referring. Animals (including humans)
break down carbohydrates during the process of metabolism to release energy. For example, the chemical metabolism of the sugar glucose is shown below:
C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy
Animals obtain carbohydrates by eating foods that contain them, for example potatoes, rice,
breads, etc. These carbohydrates are manufactured by plants during the process of photosynthesis. Plants harvest energy from sunlight to run the reaction described above in reverse:
6 CO2 + 6 H2O + energy (from sunlight) C6H12O6 + 6
Vitamins are nutrients you must get from food.
You need only small amounts (that's why they are often referred to as micronutrients)
because the body uses them without breaking them down, as happens to carbohydrates and other macronutrients.
So far, 13 compounds have been classified as vitamins. Vitamins A, D, E, and K, the four fat-soluble vitamins, tend to accumulate
in the body. Vitamin C and the eight B vitamins-biotin, folate, niacin, pantothenic acid, riboflavin, thiamin, vitamin B6,
and vitamin B12-dissolve in water, so excess amounts are excreted.
The "letter" vitamins sometimes go by different names. These include:
Vitamin A = retinol, retinaldehyde, retinoic acid Vitamin B1 = thiamin Vitamin B2
= riboflavin Vitamin B6 = pyridoxine, pyridoxal, pyridoxamine Vitamin B12 = cobalamin Vitamin
C = ascorbic acid Vitamin D = calciferol Vitamin E = tocopherol, tocotrienol Vitamin
K = phylloquinone
Vitamin A does much more than help you see in the dark. It stimulates the production and activity of white blood cells,
takes part in remodeling bone, helps maintain the health of endothelial cells (those lining the body's interior surfaces),
and regulates cell growth and division. This latter role had researchers exploring for years whether insufficient vitamin
A caused cancer. Several studies have dashed this hypothesis,(1) as have randomized trials of supplements containing beta carotene, a precursor of vitamin A.
Although it's relatively easy to get too little vitamin A, it's also easy to get too much. Intake of up to 10,000 IU, twice
the current recommended daily level, is thought to be safe. However, there is some evidence that this much preformed vitamin
A might increase the risk of hip fracture (2) or some birth defects.(3)
Optimal Intake:The current recommended intake of vitamin A is 5,000 IU for men and 4,000 IU for women.
Many breakfast cereals, juices, dairy products, and other foods are fortified with vitamin A. Many fruits and vegetables,
and some supplements, also contain beta-carotene and other vitamin A precursors, which the body can turn into vitamin A. In
contrast to preformed vitamin A, beta-carotene is not toxic even at high levels of intake. The body can form vitamin A from
beta-carotene as needed, and there is no need to monitor intake levels, as there is with preformed vitamin A. Therefore, it
is preferable to choose a vitamin supplement that has all or the vast majority of its vitamin A in the form of beta-carotene.
Another reason to avoid too much preformed vitamin A is that it may interfere with the beneficial actions of vitamin D.
The 3 Bs: Vitamin B6, Vitamin B12, and Folic Acid
One of the advances that changed the way we look at vitamins was the discovery that too little folic acid, one of the eight
B vitamins, is linked to birth defects such as spina bifida and anencephaly. Fifty years ago, no one knew what caused these
birth defects, which occur when the early development of tissues that eventually become the spinal cord, the tissues that
surround it, or the brain goes awry. Twenty five years ago, British researchers found that mothers of children with spina
bifida had low vitamin levels.(4) Eventually, two large trials in which women were randomly assigned to take folic acid or a placebo showed that getting too
little folic acid increased a woman's chances of having a baby with spina bifida or anencephaly and that getting enough folic
acid could prevent these birth defects.(5,6)
Enough folic acid, at least 400 micrograms a day, isn't always easy to get from food. That's why women of childbearing
age are urged to take extra folic acid. It's also why the US Food and Drug Administration now requires that folic acid be
added to most enriched breads, flour, cornmeal, pastas, rice, and other grain products, along with the iron and other micronutrients
that have been added for years.(7)
The other exciting discovery about folic acid and two other B vitamins is that they may help fight heart disease and some types of cancer. It's too early to tell if there's merely an association between increased intake of folic acid and other B vitamins
and heart disease or cancer, or if high intakes prevent these chronic diseases.
B Vitamins and Heart Disease
In 1968, a Boston pathologist investigaed the deaths of two children from massive strokes. Both had inherited conditions
that caused them to have high levels of a protein breakdown product called homocysteine in their blood, and both had arteries
as clogged with cholesterol as those of a 65-year-old fast food addict.(8) Putting one and one together, he hypothesized that high levels of homocysteine contribute to the artery-clogging process
of atherosclerosis. Since then, some-but not all-studies have linked high levels of this breakdown product, called homocysteine,
with increased risks of heart disease and stroke.(9,10)
Folic acid, vitamin B6, and vitamin B12 play key roles in recycling homocysteine into methionine, one of the 20 or so building
blocks from which the body builds new proteins. Without enough folic acid, vitamin B6, and vitamin B12, this recycling process
becomes inefficient and homocysteine levels increase. Several observational studies show that high levels of homocysteine
are associated with increased risks of heart disease and stroke. Increasing intake of folic acid, vitamin B6, and vitamin
B12 decreases homocysteine levels. And some observational studies show lower risks of cardiovascular disease among people
with higher intakes of folic acid, those who use multivitamin supplements, or those with higher levels of serum folate (the
form of folic acid found in the body). However, other prospective studies show little or no association between homocysteine
and cardiovascular disease.
The first large trial of homocysteine to be completed ended with negative results. In the Vitamin Intervention for Stroke
Prevention trial, 3680 adults who had had nondisabling strokes took a pill containing high doses of vitamins B6, B12, and
folic acid or one containing low doses of these three B vitamins. After two years, second strokes, heart attacks and other
coronary heart disease events, and deaths were the same in the two groups. However, in that trial, high levels of homocysteine
at baseline were associated with higher risk of cardiovascular disease. Other ongoing randomized trials, such as the Women's
Antioxidant Cardiovascular Study (11) and the Vitamin Intervention in Stroke Prevention Study (12) should yield more definitive answers regarding homocysteine, B vitamins, and cardiovascular risk.
Folic Acid and Cancer
In addition to recycling homocysteine, folate plays a key role in building DNA, the complex compound that forms our genetic
blueprint. Observational studies show that people who get higher than average amounts of folic acid from their diets or supplements
have lower risks of colon cancer(13) and breast cancer.(14) This could be especially important for those who drink alcohol, since alcohol blocks the absorption of folic acid and inactivates
circulating folate. An interesting observation from the Nurses' Health Study is that high intake of folic acid blunts the
increased risk of breast cancer seen among women who have more than one alcoholic drink a day.(14)
Optimal Intake:The definition of a healthy daily intake of B vitamins isn't set in stone, and is
likely to change over the next few years as data from ongoing randomized trials are evaluated. Because only a fraction of
U.S. adults currently get the recommended daily intake of B vitamins by diet alone, use of a multivitamin supplement will
become increasingly important.
Folic Acid: The current recommended intake for folic acid is 400 micrograms per day. There are many excellent sources
of folic acid, including prepared breakfast cereals, beans, and fortified grains.
Vitamin B6: A healthy diet should include 1.3 to 1.7 milligrams of vitamin B6. Higher doses have been tested as
a treatment for conditions ranging from premenstrual syndrome to attention deficit disorder and carpal tunnel syndrome. To
date, there is little evidence that it works.
Vitamin B12: The current recommended intake for vitamin B12 is 6 micrograms per day. Vitamin B12 deficiency can
be caused by pernicious anemia, due to a lack of "intrinsic factor" (a substance secreted by gastric cells that binds to vitamin
B12 and enables its absorption). A more common cause of deficiency is often diagnosed in older people who have difficulty
absorbing vitamin B12 from unfortified foods; such people can typically absorb vitamin B12 from fortified foods or supplements,
however, providing yet another reason to take a multivitamin. Symptoms of B12 deficiency include memory loss, disorientation,
hallucinations, and tingling in the arms and legs. Some people diagnosed with dementia or Alzheimer's disease are actually
suffering from the more reversible vitamin B12 deficiency.
Vitamin C: Vitamin C has been in the public eye for a long time. Even before its discovery in 1932, nutrition experts
recognized that something in citrus fruits could prevent scurvy, a disease that killed as many as 2 million sailors
between 1500 and 1800.(15) More recently, Nobel laureate Linus Pauling promoted daily megadoses of vitamin C (the amount in 12 to 24 oranges) as a way
to prevent colds and protect the body from other chronic diseases.
There's no question that vitamin C plays a role in controlling infections. It's also a powerful antioxidant that can neutralize
harmful free radicals, and it helps make collagen, a tissue needed for healthy bones, teeth, gums, and blood vessels.(16) The question is, do you need lots of vitamin C to keep you healthy?
No. Vitamin C's cold-fighting potential certainly hasn't panned out. Small trials suggest that the amount of vitamin C
in a typical multivitamin taken at the start of a cold might ease symptoms, but there's no evidence that megadoses make a
difference, or that they prevent colds.(17) Studies of vitamin C and heart disease, cancer, and eye diseases such as cataract and macular degeneration also show no clear
Optimal Intake: The current recommended dietary intake for vitamin C is 90 mg for men and 75 mg for women
(add an extra 35 mg for smokers). There's no good evidence that megadoses of vitamin C improve health. As the evidence continues
to unfold, 200 to 300 mg of vitamin C a day appears to be a good target. This is easy to hit with a good diet and a standard
multivitamin. Excellent food sources of vitamin C are citrus fruits or citrus juices, berries, green and red peppers, tomatoes,
broccoli, and spinach. Many breakfast cereals are also fortified with vitamin C.
Vitamin D: If you live north of the line connecting San Francisco to Philadelphia, odds are you don't get enough
vitamin D. The same holds true if you don't, or can't, get outside for at least a 15-minute daily walk in the sun. African-Americans
and others with dark skin tend to have much lower levels of vitamin D, due to less formation of the vitamin from the action
of sunlight on skin. A study of people admitted to a Boston hospital, for example, showed that 57% were deficient in vitamin
Vitamin D helps ensure that the body absorbs and retains calcium and phosphorus, both critical for building bone. Laboratory
studies also show that vitamin D keeps cancer cells from growing and dividing.
Some preliminary studies indicate that insufficient intake of vitamin D is associated with an increased risk of fractures,
and that vitamin D supplementation may prevent them.(19) It may also help prevent falls, a common problem that leads to substantial disability and death in older people.(20) Other early studies suggest an association between low vitamin D intake and increased risks of prostate, breast, colon,
and other cancers.(21)
Optimal Intake:The current recommended intake of vitamin D is 5 micrograms up to age 50, 10 micrograms
between the ages of 51 and 70, and 15 micrograms after age 70. Optimal intakes are higher, though, with 25 micrograms (1000
IU) recommended for those over age 2. Very few foods naturally contain vitamin D. Good sources include dairy products and
breakfast cereals (which are fortified with vitamin D), and fatty fish such as salmon and tuna. For most people, the best
way to get the recommended daily intake is by taking a multivitamin, but the level in most multivitamins (10 micrograms) is
Vitamin E: For a time, vitamin E supplements looked like an easy way to prevent heart disease. Promising observational
studies, including the Nurses' Health Study(22) and Health Professionals Follow-up Study,(23) suggested 20% to 40% reductions in coronary heart disease risk among individuals who took vitamin E supplements (usually
containing 400 IU or more) for least two years.(24)
The results of several randomized trials have dampened enthusiasm for vitamin E's ability to prevent heart attacks or deaths
from heart disease among individuals with heart disease or those at high risk for it. In the GISSI Prevention Trial, the results
were mixed but mostly showed no preventive effects after more than three years of treatment with vitamin E among 11,000 heart
attack survivors.(25) Results from the Heart Outcomes Prevention Evaluation (HOPE) trial also showed no benefit of four years worth of vitamin
E supplementation among more than 9,500 men and women already diagnosed with heart disease or at high risk for it.(26) Based on these and other studies, the American Heart Association has concluded that "the scientific data do not justify the
use of antioxidant vitamin supplements [such as vitamin E] for CVD risk reduction." (27)
A recent scientific analysis raised questions about whether high doses of vitamin E supplements might increase the risk
of dying.(28) The authors gathered and re-analyzed data from 19 clinical trials of vitamin E, including the GISSI and HOPE studies; they
found a higher rate of death in trials where patients consumed more than 400 IU of supplements per day. While this meta-analysis
drew headlines when it was released online in November 2004, there are limitations to the conclusions that can be drawn from
it. Some of the findings are based on very small studies; furthermore, many of the high-dose trials of Vitamin E included
in the analysis were done on people who had chronic diseases, such as heart disease or Alzheimer's disease. So it is not clear
that these findings would apply to healthy people.
It's entirely possible that in secondary prevention trials, the use of drugs such as aspirin, beta blockers, and ACE inhibitors
mask a modest effect of vitamin E, and that it may have benefits among healthier people. Ongoing randomized trials of vitamin
E, such as the Women's Health Study (29) and SU.VI.MAX (30) will tell us more about its possible benefits in the coming years.
Optimal Intake: The recommended daily intake of vitamin E from food now stands at 15 milligrams from food.
That's the equivalent of 22 IU from natural-source vitamin E or 33 IUs of the synthetic form. Researchers are still writing
the book on vitamin E. Some small studies have suggested that vitamin E supplements might interfere with statins, but this
hypothesis was refuted in a large trial. While the data are sparse and conflicting, evidence from some observational studies
suggests that at least 400 IU of vitamin E per day, and possibly more, are needed for optimal health. Since standard multivitamins
usually contain around 30 IU, a separate vitamin E supplement is needed to achieve this level. Current guidelines say that
consuming more than 1000 mg of supplemental vitamin E per day is not considered safe; that's the equivalent of a supplement
with 1,500 IU of natural-source vitamin E or 1,100 IU of synthetic vitamin E.
Vitamin K: Vitamin K helps make six of the 13 proteins needed for blood clotting. Its role in maintaining the clotting
cascade is so important that people who take anticoagulants such as warfarin (Coumadin) must be careful to keep their vitamin
K intake stable.
Lately, researchers have demonstrated that vitamin K is also involved in building bone. Low levels of circulating vitamin
K have been linked with low bone density, and supplementation with vitamin K shows improvements in biochemical measures of
bone health.(31) A report from the Nurses' Health Study suggests that women who get at least 110 micrograms of vitamin K a day are 30% less
likely to break a hip as women who get less than that.(32) Among the nurses, eating a serving of lettuce or other green leafy vegetable a day cut the risk of hip fracture in half when
compared with eating one serving a week. Data from the Framingham Heart Study also shows an association between high vitamin
K intake and reduced risk of hip fracture.(33)
Optimal Intake:The recommended daily intake for vitamin K is 80 micrograms for men and 65 for women.
Because this vitamin is found in so many foods, especially green leafy vegetables and commonly used cooking oils, most adults
get enough of it. According to a 1996 survey, though, a substantial number of Americans, particularly children and young adults,
aren't getting the vitamin K they need.(34)
Our cells must constantly contend with nasty substances called free radicals. They can damage DNA, the inside or artery
walls, proteins in the eye--just about any substance or tissue imaginable. Some free radicals are made inside the body, inevitable
byproducts of turning food into energy. Others come from the air we breathe and the food we eat.
We aren't defenseless against free radicals. We extract free-radical fighters, called antioxidants, from food. Fruits,
vegetables, and other plant-based foods deliver dozens, if not hundreds, of antioxidants. The most common are vitamin C, vitamin
E, beta-carotene and related carotenoids. Food also supplies minerals such as selenium and manganese, which are needed by
enzymes that destroy free radicals.
During the 1990s, the term antioxidants became a huge nutritional buzz word. Antioxidants were promoted as wonder agents
that could prevent heart disease, cancer, cataracts, memory loss, and a host of other conditions.
It's true that the package of antioxidants, minerals, fiber, and other substances found in fruits, vegetables, and
whole grains help prevent a variety of chronic diseases. Whether high doses vitamin C, vitamin E, or other antioxidants can
accomplish the same feat is an open question.
The evidence accumulated so far isn't promising. Randomized trials of vitamin C, vitamin E, and beta-carotene haven't revealed
much in the way of protection from heart disease, cancer, or aging-related eye diseases. Ongoing trials of other antioxidants,
such as lutein and zeaxanthin for macular degeneration and lycopene for prostate cancer, are underway.
The Bottom Line
A standard multivitamin supplement doesn't come close to making up for an unhealthy diet. It provides a dozen or so of
the vitamins known to maintain health, a mere shadow of what's available from eating plenty of fruits, vegetables, and whole
grains. Instead, a daily multivitamin provides a sort of nutritional safety net.
While most people get enough vitamins to avoid the classic deficiency diseases, relatively few get enough of five key vitamins
that may be important in preventing several chronic diseases. These include:
Reference: World Cancer Research Fund. Food, Nutrition and Cancer. Washington, DC: American Institute for Cancer
c. Nucleic Acids
Vitamins and Minerals
Water and Solutions
Most vitamins must be provided by the diet or by supplements; only three vitamins (D,
K, and the B vitamin biotin) can be manufactured in the body from nondietary sources. Vitamins are not sources of energy as
are carbohydrates, fats, and proteins. Instead, vitamins serve as chemical partners for the enzymes involved in the body's
metabolism, cell production, tissue repair, and other vital processes. Vitamins are either fat soluble or water soluble. The
fat-soluble vitamins, which include A, D, E, and K, are absorbed by the body using processes that closely parallel the absorption
of fat. They are stored in the liver and used up by the body very slowly. The water-soluble vitamins include C and the B complex
vitamins. The body uses these vitamins very quickly; excess amounts are eliminated in urine.