sight and life - vitamins: a brief guide
DESCRIPTION
includes an overview of all water- and fatsoluble vitamins, their prime natural sources, their roles and physical symptoms of deficienciesTRANSCRIPT
Vitamins: a brief guide
A Sight and Life publication
Vitamins: a brief guide
Carbon-neutral production
Sight and Life Press c/o Sight and Life / DSM Nutritional Products Ltd PO Box 2116 4002 Basel, Switzerland Phone +41 (0) 61 815 88 23 Fax +41 (0) 61 815 81 90 Email [email protected] Web www.sightandlife.org
Copywriting and communication consultancy by The Corporate Story Ltd, Windsor, United Kingdom Design concept, layout, typesetting and graphics by S1 Communication Design, Augsburg, Germany Printed by Burger Druck, Waldkirch, Germany
Vitamins are organic nutrients which are essential for life. The human body requires these nutrients to ensure normal metabolism, growth and physical well-being. Most vitamins are not made in the body, or only in in-sufficient amounts to meet our needs. They therefore have to be obtained primarily through the food we eat. Vitamins are classed as micronutrients, and are present in food in minute quantities compared to macronutrients (protein, carbohydrates and fat). In industrialized countries, the average adult eats approximately 600 g of food per day on a dry-weight basis, of which less than 1 g consists of vitamins. Each of the 13 vitamins known today has specific functions in the body, which makes each of them unique and irreplaceable. No single food contains the full range of vitamins, and inadequate vitamin intake results in vitamin deficiency disorders. A balanced and varied diet is therefore vital to meet the body’s vitamin requirements. Of the 13 known vitamins, four are fat-soluble, namely vitamins A, D, E and K. The others are water-soluble: vitamin C and the B-complex, consisting of vitamins B1, B2, B6, B12, niacin, folic acid, biotin and pantothenic acid.
What is a vitamin?
Sorghum crop in Kenya
The history of vitamins
Local fruits on a market in Bangladesh Vita
min
Alte
rnat
ive
nam
e
Disc
over
yIs
olat
ion
Stru
ctur
eSy
nthe
sis
Vita
min
ARe
tinol
1909
1931
1931
1947
Prov
itam
in A
β-
caro
tene
1831
1831
1930
1950
Vita
min
DCa
lcife
rol
1918
1932
1936
1959
Vita
min
ETo
coph
erol
1922
1936
1938
1938
Vita
min
KPh
yllo
quin
one
1929
1939
1939
1939
Vita
min
B1
Thia
min
e18
9719
2619
3619
36
Vita
min
B2
Ribo
flavi
n19
2019
3319
3519
35
Vita
min
B3
Niac
in19
3619
3619
3719
94
Vita
min
B5
Pant
othe
nic
acid
1931
1938
1940
1940
Vita
min
B6
Pyri
doxi
ne19
34
1938
1938
1939
Vita
min
B7
Biot
in19
3119
3519
4219
43
Vita
min
B9
Folic
aci
d 19
4119
4119
4619
46
Vita
min
B12
Coba
lam
in
1926
1948
1956
1972
Vita
min
CAs
corb
ic a
cid
1912
1928
1933
1933
This
dat
a ha
s be
en a
ssem
bled
in g
ood
faith
and
on
the
basi
s of
ext
ensi
ve s
econ
dary
rese
arch
it s
houl
d be
not
ed, h
owev
er, t
hat s
ome
sour
ces
disa
gree
con
cern
ing
indi
vidu
al d
ates
.
The discovery of the concept of vitamins
A century ago, a Polish-American scientist attempted to isolate the first vitamin (B1) from rice bran. Casimir (born Kazimierz) Funk named his dis-covery “vitamine”, believing that this was an amine vital for life. This coin-age has come down to us in the slightly altered form of “vitamin.” Funk’s breakthrough discovery played a decisive role in the development of an en-tire scientific framework of thought, which the world now takes for granted. Funk (1884 –1967) was the first scientist to suggest the existence of an entire family of organic substances essential for life, and the first to give these substances a name that made their function clear – even though most vitamins were later shown not to be amines. He was not the only scientist working in this field at the time, but he was, one might say, the Godfather of the vitamins movement. In a distinguished scientific career spanning two world wars, Funk studied and worked in Europe and the United States. He had roles in academia and industry, improved manufacturing methods for commercial drugs, and became President of the Funk Foundation for Medical Research. Although he never received a Nobel Prize for his work, the Polish Institute of Arts and Sciences of America presents the Casimir Funk Natural Sciences Award annually to a Polish-American scientist.
Various types of rice sold on a market in Bangladesh
The first vitamin to be named was vitamin A. The use of the letter A was the brainchild of the American biochemist Elmer McCollum. He rejected Casimir Funk’s term ‘vitamine’ in favor of ‘Unidentified dietary factor fat-soluble A’ because the substance discovered by McCollum did not contain nitrogen (amines are organic compounds derived from ammonia, and always contain nitrogen). In 1921, the British biochemist Sir Jack Cecil Drummond suggested com-bining the use of letters of the alphabet with the term ‘vitamin’ to denote a range of related organic micronutrients. These micronutrients consequently became known as vitamins A, B, C and so on. The eight water-soluble B vitamins were originally thought to be a single substance class, but were subsequently found to be chemically distinct from one another, which is why they are differentiated by means of suffixed numbers – B1, B2 and so forth.
How the vitamins got their names
Locally grown legumes on a market stall in Zambia
While plants and micro-organisms can themselves produce the vitamins necessary for the metabolism, humans and animals lost this ability during the course of evolution. Lacking the enzymes necessary for synthesizing vitamins in the body, humans and animals therefore have to take these in via the diet (with the exception of vitamin D, which is synthesized via the action of sunlight). It was recognized more than 3,500 years ago that foods containing vitamins are essential for health and well-being. The earliest records to have come down to us on this subject relate to the use of specific foods like liver – which contains vitamin A – to prevent diseases such as night blindness. Never- theless the concept of vitamins per se was quite unknown until very recently.
A balanced diet is necessary for adequate vitamin intake. A lack of the nec-essary vitamins in the diet can lead to vitamin deficiency disorders, such as scurvy (vitamin C deficiency),and beriberi (vitamin B1 deficiency).
Since the beginning of the 20th century, our knowledge of the biological function of vitamins on the molecular and cellular level has increased signi-ficantly. This understanding is reflected by the award of 20 Nobel Prizes in this field between 1928 and 1967. Despite intensive research efforts, how-ever, no additional vitamins have been added to the list of 13 vitamins defined during the 20th century.
Vitamins in human nutrition
Fruits, vegetables, dairy and animal products provide a well-balanced diet
ARetinol | β-caroteneDiscovery of active ingredient: 1909 | 1831 (Provitamin A)Isolation: 1931 | 1831 (Provitamin A)
The prime natural sources of vitamin AAnimal products: Liver, egg yolk, butter, whole milk, cheese
Vegetable products in the form of carotenoids (provitamin A):Certain fruits (i.e. melon, apricot), green leafy vegetables (i.e. spinach, broccoli), carrots, pumpkins, palm oil
The role of vitamin A> Plays a role in mechanisms required for sight (11-cis retinal is the
chromophore in the visual cycle)> Essential for growth and development> Required for healthy skin, epithelia and mucosa> Effects on certain endocrine glands> Important for fertility> Essential for proper immune functions
β-Carotene: Provitamin A, biological antioxidant
Physical symptoms of vitamin A deficiency> Delayed growth and development> Night-blindness> Ocular lesions and xerophthalmia> Cutaneous lesions (dry and rough skin)> Impaired immune functions> Destruction of epithelial tissue (i.e. in lungs, intestines,
urinary tract, genitals)
Groups at risk of deficiency:> Pregnant and lactating women> Infants and young children> Populations suffering from poor nutrition (i.e. only rice, maize,
potatoes as staple foods)
Fat-s
olub
leVitamin
Prime natural sources
Animal products
Liver | Egg yolk | Dairy products
Vegetable products
Fruits | Leafy vegetables | Carrots
DThe prime natural sources of vitamin DAnimal products (main source for D3 ): Oily fish, egg yolk
Plant products (main source for D2): Mushrooms
Other: Synthesized in the skin by the action of ultraviolet lightVitamin D3 is superior to vitamin D2 in increasing and maintaining 25(OH)D serum levels
The role of vitamin D> Regulation of metabolism of calcium and phosphorus> Essential for normal bone development and maintenance> Plays a role in innate immunity by stimulating immune cells proliferation
and cytokine production
Physical symptoms of vitamin D deficiency> Rickets in children> Osteomalacia in adults
Groups at risk of deficiency:> Populations suffering from poor nutrition (i.e. only rice, maize,
potatoes as staple foods)
Fat-s
olub
leVitamin
Prime natural sources
Animal products
Oily fish | Egg yolk –> D3
Vegetable products
Mushrooms –> D2
D2 ErgocalciferolD3 Cholecalciferol Discovery of active ingredient: 1918Isolation: 1932
The prime natural sources of vitamin EAnimal products: Milk, butter, eggs
Vegetable products:Vegetable oils, cereal germ, vegetables (i.e. spinach, lettuce, cabbage, avocados), nuts
The role of vitamin E> Biological antioxidant> Protects lipids (cell membranes), proteins, and DNA from
oxidation and thereby contributes to cellular health> Assists fertility
Physical symptoms of vitamin E deficiency> Leads to destruction of red blood cells> Impaired immune function > Long-term impact includes neuromusclar diseases
Groups at risk of deficiency:> Newborn babies, particularly premature> Individuals unable to efficiently absorb fats from the intestine
Fat-s
olub
leVitamin
EPrime natural sources
Animal products
Dairy products | Eggs
Vegetable products
Vegetable oils | Vegetables | Nuts
Tocopherols and TocotrienolsMain vitamin E activity:α-Tocopherol (Natural RRR- and all-rac α-Tocopherol)Discovery of active ingredient: 1922 | Isolation: 1936
K1 PhylloquinoneK2 MenaquinonesDiscovery of active ingredient: 1929Isolation: 1939
Fat-s
olub
le
The prime natural sources of vitamin KAnimal products (main source for K2):Some dairy products (i.e. cheese & curd cheese),meat including liver
Vegetable products (main source for K1):Green leafy vegetables (i.e. parsley, spinach), cauliflower
Other: Fermented soybeans
The role of vitamin K> Essential anti-haemorrhaging agent (promotes blood clotting)> Helps to maintain bone health> Emerging evidence for potential role in cardiovascular health
Physical symptoms of vitamin K deficiency> Ecchymosis> Petechiae> Hematomas> Oozing of blood at surgical or puncture sites> In infants, birth defects such as underdevelopment of the face,
nose, bones and fingers
Groups at risk of deficiency:> Newborn babies (due to lack of intake)
KVitamin
Prime natural sources
Animal products
Dairy products | Meat | Liver
Vegetable products
Green vegetables | Cauliflower
B1ThiamineDiscovery of active ingredient: 1897Isolation: 1926
Wat
er-s
olub
le
The prime natural sources of vitamin B1 Animal products: Offal (liver, kidneys, heart), fish, meat (porc)
Vegetable products: Cereals, leafy vegetables, fruits (dried), pulses, nuts
Other: Brewer’s yeast
The role of vitamin B1 > Energy metabolism (co-enzyme)> Essential for metabolism of carbohydrates, lipids, proteins (co-enzyme)> Required for proper functioning of the nervous system and
muscles, which has implications for proper functioning of the cardiovascular system
Physical symptoms of vitamin B1 deficiency> Beriberi (still occurs in South-East Asia)
Groups at risk of deficiency:> Alcoholics
Vitamin
Prime natural sources
Animal products
Offal | Fish | Meat
Vegetable products
Cereals | Vegetables | Fruits | Pulses
B2RiboflavinDiscovery of active ingredient: 1920Isolation: 1933
The prime natural sources of vitamin B2 Animal products: Offal (liver, kidneys, heart), eggs, meat, milk, cheeses
Vegetable products: Cereals, vegetables
Other: Brewer’s yeast
The role of vitamin B2 > Essential for the metabolism of carbohydrates, lipids and proteins
(co-enzyme in many reactions)> General effect on tissues and organs (maintains health of mucosa)> Stimulates growth and reproduction> Plays a role in sight mechanisms> Conversion of vitamin (B6, folic acid and niacin) into their active
co-enzyme forms
Physical symptoms of vitamin B2 deficiency> Skin and tissue membrane lesions (lips, tongue,
fissures at corners of mouth)> Ocular symptoms (corneal vascularisation associated with
sensitivity to bright light, impaired vision, itching)> Inflamed mucosal membranes
Groups at risk of deficiency:> Individuals whose food intake is unadequate> The elderly> Chronic dieters> Individuals who exclude milk products from their diet
Vitamin
Prime natural sources
Animal products
Offal | Eggs | Meat | Milk | Cheeses
Vegetable products
Cereals | Vegetables
Wat
er-s
olub
le
B3Niacin; PP; Nicotinic Acid; Nicotinic AmideDiscovery of active ingredient: 1936Isolation: 1936Identification with nicotinic acid: 1937
The prime natural sources of vitamin B3 Animal products: Offal (liver, kidneys, heart), fish, meat
Vegetable products: Cereals, pulses, fruit (avocados, figs, dates, prunes), nuts
Other: Synthesized from tryptophan
The role of vitamin B3 > Required for the energy supply to all metabolic reactions in the body> Required for growth
Physical symptoms of vitamin B3 deficiency> Pellagra> Skin lesions> Digestive inefficiency> Insomnia> Fatigue> Loss of appetite
Groups at risk of deficiency:> Chronic alcoholics> Individuals whose staple diet is maize or barley> Patients with Hartnup’s disease
Vitamin
Prime natural sources
Animal products
Offal | Fish | Meat
Vegetable products
Cereals | Pulses | Fruits | Nuts
Wat
er-s
olub
le
The prime natural sources of vitamin B5 Animal products: Offal (liver, kidneys), meat (chicken, beef), egg yolk, milk, fish
Vegetable products: Cereals, nuts, vegetables (i.e. white mushrooms)
Other: Synthesized by intestinal microorganisms
The role of vitamin B5 > Required for the synthesis of co-enzyme A and acyl carrier protein (ACP)> Key role in metabolism of carbohydrates, proteins and fats> Important for maintenance and repair of tissues and cells
(skin, hair, and membranes)> Helps in healing of wounds and lesions> Pantethine (dimeric form of vitamin B5) normalizes blood lipid profiles
Physical symptoms of vitamin B5 deficiency> Nausea> Vomiting> Headaches> Tingling sensations (‘burning feet’ syndrome)
Groups at risk of deficiency:> Individuals whose diet is lacking in the other B vitamins
B5Pantothenic AcidDiscovery of active ingredient: 1931Isolation: 1938
Vitamin
Prime natural sources
Animal products
Offal | Meat | Egg yolk
Vegetable products
Cereals | Nuts | Vegetables
Wat
er-s
olub
le
The prime natural sources of vitamin B6 Animal products: Chicken, liver (cattle, pig), fish (salmon, tuna, sardines, halibut, herring)
Vegetable products: Nuts (walnut, peanut), corn and whole grain cereals, bread, vegetables, fruit
The role of vitamin B6 > Required for the majority of biological reactions (i.e. amino acid
metabolism, antibody production, neurotransmitter synthesis, red blood cell formation)
Physical symptoms of vitamin B6 deficiency> Deficiency of vitamin B6 alone is uncommon;
usually it occurs in combination with a deficit in other B-vitamins> Poor growth> Kidney stones> Depression> General fatigue> Dizziness> Nerve problems> Irritability> Convulsions> Cutaneous lesions
Groups at risk of deficiency:> Pregnant and breastfeeding women> The elderly> Underweight individuals> Alcoholics
B6PyridoxineDiscovery of active ingredient: 1934Isolation: 1938
Vitamin
Prime natural sources
Animal products
Chicken | Liver | Fish
Vegetable products
Nuts | Cereals | Bread | Vegetables
Wat
er-s
olub
le
The prime natural sources of vitamin B7 Animal products:Offal (liver, kidneys), meat (pork, mutton, poultry), egg yolk
Vegetable products: Vegetables, cereals, nuts (walnuts, peanuts)
Other: Synthesized by intestinal bacteria
The role of vitamin B7 > Involved in many cellular reactions> Intermediary metabolism of carbohydrates, fats and proteins,
particularly in protein metabolism of hair roots and finger nail cells
Physical symptoms of vitamin B7 deficiency> Deficiency due to lack of dietary intake is rare> General fatigue> Nausea> Neurological problems> Poor skin and hair quality
Groups at risk of deficiency:> Patients maintained on total parental nutrition> People who eat large amounts of raw egg white> Haemodialysis patients> Diabetes mellitus sufferers> Individuals receiving long-term anticonvulsant therapy
B7Biotin; Vitamin HDiscovery of active ingredient: 1931Isolation: 1935
Vitamin
Prime natural sources
Animal products
Offal | Meat | Egg yolk
Vegetable products
Vegetables | Cereals | Nuts
Wat
er-s
olub
le
B9Folate (including folic acid and naturally occurring folates)Discovery of active ingredient: 1941Isolation: 1941
The prime natural sources of vitamin B9 Animal products: Liver, dairy products, milk, egg yolk
Vegetable products: Dark green leafy vegetables, beets, wheat germ, yeast, peanuts, oranges
The role of vitamin B9 > Required for the production of nucleic acids and in cell reproduction
(i.e. red and white blood cells, nerve cells)
Physical symptoms of vitamin B9 deficiency> Tiredness> Loss of appetite> Fewer but larger red blood cells (megaloblastic or macrocytic anemia)> Weakness> Neurological problems> Digestive problems
Groups at risk of deficiency:> The elderly (due to lower food intake)> Underweight people > Alcoholics
Vitamin
Prime natural sources
Animal products
Liver | Dairy products | Egg yolk
Vegetable products
Leafy vegetables | Peanuts | Oranges
Wat
er-s
olub
le
B12CyanocobalaminDiscovery of active ingredient: 1926Isolation: 1948
The prime natural sources of vitamin B12 Animal products: Offal (liver, kidneys, heart, brain), meat, eggs, fish, dairy products
The role of vitamin B12> Required for the formation of red blood cells to prevent anemia> Essential growth factor> Regeneration of folate> Involved in fat and carbohydrate metabolism> Essential for co-enzyme function, especially in cells of the nervous tissue,
bone marrow and gastrointestinal tract
Physical symptoms of vitamin B12 deficiency> Pernicious anemia> General fatigue> Loss of appetite> Gastric atrophy> Neuromuscular pain> Neurological problems (gait, memory)
Groups at risk of deficiency:> Vegetarians> The elderly
Vitamin
Prime natural sources
Animal products
Offal | Meat | Eggs | Fish | Dairy products
Wat
er-s
olub
le
CAscorbic Acid Discovery of active ingredient: 1912Isolation: 1928
Vitamin
Prime natural sources
Animal products
Milk | Liver
Vegetable products
Fruits | Vegetables | Lettuce
The prime natural sources of vitamin C Animal products: Milk, liver (ox /calf)
Vegetable products: Fruits (especially citrus fruits), vegetables, lettuce
The role of vitamin C > Multiple roles at a tissue and cell level (synthesis of collagen,
absorption of iron, formation of carnitine and tyrosine)> Biological antioxidant (free radical scavenger)> Stimulates the body’s immune system: defenses against infections
and inflammation
Physical symptoms of vitamin C deficiency> Scurvy (fatigue, loss of appetite and weight,
lowered immune resistance to infections)
Groups at risk of deficiency:> Smokers (active and passive)> Individuals with a low-vitamin diet
Wat
er-s
olub
le
