Vitamin and mineral supplements Vitamine complex

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					       CONTINUING EDUCATION

             VITAMIN AND MINERAL SUPPLEMENTS
                                                         By Colin Waine FRCGP, FRC Path

        For most people, supplementing the diet
             with vitamins and minerals is not
                necessary and could be harmful.
            Pharmacists should advise people to
           concentrate on eating a healthy, well
         balanced diet rather than resorting to
                       dietary supplementation




      V
                   itamins are organic nutrients
                   that are necessary in small
                   amounts for normal metabolism
                   and good health. However, the
      term vitamin has come to refer to any
      organic dietary constituent necessary for life
      and growth that does not function by pro-
      viding energy. Most vitamins have to be
      obtained from the diet or by supplementa-
      tion, because only two — D and K — can be
      manufactured by the body from non-dietary
      sources.
           Vitamins are not sources of energy in
      the same way as carbohydrates, fats and pro-
      teins are but they serve as chemical partners
      for the enzymes involved in metabolism, cell
      production, tissue repair and other vital         deemed to be necessary to maintain health.      be increased during pregnancy and after
      processes. Vitamin deficiencies have an           All RDAs can be achieved by eating a well       haemorrhage). Iron overload can cause
      adverse effect on these processes and specif-     balanced diet (they are shown in Table 1).      haemosiderosis. Normally only about 3–6
      ic diseases are linked to a lack of individual                                                    per cent of the amount ingested is absorbed.
      vitamins. Vitamins can be prescribed on           ABSORPTION OF VITAMINS AND                      Although iron is more readily absorbed in a
      National Health Service prescriptions to          MINERALS
                                                                                                        ferrous state, most dietary iron is in the fer-
      prevent or treat deficiency. Their use as a                                                       ric form. Gastric secretions dissolve ingest-
      general “pick me up” is of unproven value.        Vitamins Most vitamins are absorbed in the      ed iron enabling it to form soluble
           The shelves of pharmacies and some           upper small intestine, except vitamin B12,      complexes with ascorbic acid and other sub-
      supermarkets abound with vitamin and min-         which is absorbed in the ileum. Vitamin B12     stances that aid its reduction to the ferrous
      eral supplements. Many are heavily adver-         binds to intrinsic factor, a protein secreted   form.
      tised on the basis that if a little does you      by the stomach, and the resulting complex is         Various dietary factors can affect the
      good more will do you better. There is some       absorbed across the ileal mucosa.               availability of iron for absorption. For exam-
      evidence that intake of certain minerals and           Absorption of water-soluble vitamins is    ple, phytic acid found in cereals reacts with
      vitamins, such as calcium, folic acid, vitamin    rapid. Vitamin B12 and folate absorption are    iron to form insoluble compounds in the
      E, selenium and chromium, can reduce the          independent of sodium but all seven of the      intestine, as do phosphates and oxalates.
      risk of certain diseases in some people if tak-   remaining water-soluble vitamins — thi-         Iron absorption occurs mostly in the intes-
      en at doses above the recommended daily           amine, riboflavin, niacin, pyridoxine, pan-     tine and is increased when body iron stores
      allowance.1 However, only calcium and folic       tothenic acid, biotin and vitamin C — are       are depleted or when erythropoiesis is
      acid supplements have Department of               absorbed by carriers that are sodium            increased. Absorption is decreased under
      Health backing, and then only in the elderly,     cotransporters. Absorption of the fat-solu-     the reverse conditions.
      in women hoping to become pregnant and            ble vitamins (A, D, E and K) can be deficient
      in women during the first 12 weeks of preg-       if fat absorption is reduced eg, by lack of      TABLE 1: RDAS2,3
      nancy.                                            pancreatic enzymes.
                                                                                                        Nutrient                       RDA
           It is my opinion that taking vitamin and
      mineral supplements, other than those that        Minerals Calcium Between 30 and 80 per          Vitamin A                      10,000 IU
      have official backing, is unnecessary and         cent of ingested calcium is absorbed by         Vitamin B1 (thiamine)          1.5mg
                                                                                                        Vitamin B2 (riboflavin)        1.7mg
      potentially harmful for most people who eat       active transport out of the intestinal lumen,
                                                                                                        Vitamin B3 (niacin)            20mg
      a balanced diet.                                  although there is some absorption by passive    Vitamin B6 (pyridoxine)        2mg
                                                        diffusion. Active transport is facilitated by   Vitamin B12                    2.4–2.8mg
      RECOMMENDED DAILY ALLOWANCES                      alfacalcidol, the metabolite of vitamin D       Vitamin C (ascorbic acid)      60mg
                                                        that is produced by the kidneys. Calcium        Vitamin D                      400 IU
      Recommended daily allowances (RDAs) are           absorption is adjusted to body needs, in that   Vitamin E (tocopheryl)         30 IU
      the amounts of vitamins and minerals              absorption is increased in the presence of      Beta-carotene                  15–50mg
                                                        calcium deficiency and decreased in the         Calcium                        1,200mg
                                                        presence of calcium excess.                     Chromium                       100µg
                                                                                                        Folic acid                     0.2mg
        Dr Waine is director of health programmes and                                                   Iodine                         0.15mg
       primary care development at Sunderland Health    Iron The average daily iron intake in Europe    Iron                           15mg
                          Authority                     is about 20mg, but the amount absorbed can      Zinc                           15mg
                                                        be modified dependent upon need (eg, it can

352                                                     THE PHARMACEUTICAL JOURNAL (VOL 267)                                        15 September 2001
                                                                                                           CONTINUING EDUCATION
WHO NEEDS SUPPLEMENTS?                                  TABLE 2: DIFFERENT TYPES OF VEGETARIAN DIET9
                                                       Diet                        Description
Women Women might need supplements                     Semi- or demivegetarian Exclusion of red meat or all meat, but fish and other animal products are
when they are trying to conceive or when                                        consumed. Some people also exclude poultry.
they are pregnant. A mother’s diet can influ-          Lacto-ovo-vegetarian    Exclusion of all meat, fish and poultry. Milk, milk products and eggs are
ence the health of her baby, and vitamin or                                     consumed. At risk of vitamin B12 deficiency long term
mineral deficiencies can have serious                  Lactovegetarian         Exclusion of all meat, fish, poultry and eggs. Milk and milk products are
                                                                                consumed At risk of vitamin B12 deficiency long term
adverse effects.
                                                       Vegan                   Exclusion of all foods of animal origin. Diet comprises vegetables,
      Folic acid is especially important for                                    vegetable oils, seeds, pulses (such as beans and lentils), nuts, fruit and seeds.
women of childbearing age, because defi-                                        At risk of vitamin B12 deficiency long term
ciencies are associated with neural tube               Fruitarian              Exclusion of all foods of animal origin, as well as pulses and seeds. Diet
defects in babies and it is difficult to increase                               comprises mainly dried fruits, nuts and olive oil. People following this diet
levels through dietary manipulation.4                                           are at great risk of developing nutritional deficiencies. Such a diet requires
Therefore, women intending to conceive                                          vitamin and mineral supplementation
should take a supplement of folic acid at a            Macrobiotic             This diet progresses through a series of levels, gradually eliminating all
dose of 400µg daily. This should be contin-                                     animal produce, fruit and vegetables and leading to a restricted diet of
                                                                                cereal only. People on such diets are at grave risk of nutritional deficiency
ued for the first 12 weeks of pregnancy.
                                                                                and require vitamin and mineral supplements
      During pregnancy, iron supplements are
not necessary unless the woman develops
iron-deficiency anaemia. In this case, sup-
plements are required, because iron-defi-             by appropriate blood tests, iron-deficiency            says that vitamin D supplementation is justi-
ciancy anaemia increases the risk of low              anaemia should be treated by iron supple-              fied in anyone aged over 65 years.8
birth weight and iron-deficiency anaemia in           ments.
the baby during the first year or two of its                                                                 Vegetarians and vegans A range of diferent
life.                                                 Adults Iron-deficiency anaemia is a signifi-           types of vegetarian diets and those which
      The Department of Health recom-                 cant problem suffered by many women of                 might need to take vitamin and mineral sup-
mends that pregnant and lactating women               childbearing age, particularly if they have            plements is shown in Table 2.
should take Vitamin D supplements to com-             heavy periods and a poor dietary intake of
pensate for foetal demands.5                          iron. The Department of Health recom-                  Alcoholics Alcoholics often suffer from mul-
                                                      mends dietary supplementation with iron                tiple vitamin deficiencies, particularly of vit-
Babies and preschool children The Depart-             for women with heavy menstrual losses.5                amins B1 (thiamine), B2 (riboflavin) and B6
ment of Health recommends that between                                                                       (pyridoxine), folic acid and vitamin C. Sup-
the age of 6 months and 5 years, children             Older adults A national survey of people               plementation with vitamin B complex and
should receive supplements of vitamins A, D           aged 65 years and over7 revealed that most             vitamin C is justified.
and C.5 Iron-deficiency anaemia is not                were adequately nourished.
uncommon in young children because iron-                  However, there was concern about the               Smokers Smoking interferes with the
rich foods are generally not popular with             nutritional status of people without teeth,            absorption of a number of vitamins, particu-
them. If deficiency is present, it should be          those living in institutions, older age groups         larly that of vitamin C. Any deficiency is best
treated by giving iron supplements (doses             and those in low socio-economic groups.                remedied by making sure that the diet is rich
depend on the age and weight of the child).           There is good evidence that people living in           in fresh fruit and vegetables, rather than by
                                                      institutions benefit from supplementation              taking vitamin supplements.
Adolescents The British Nutrition Founda-             with calcium and vitamin D. This is because
tion estimates that 4 per cent of adolescent          such people often have inadequate exposure             People with vitamin deficiency As stated
boys and 17 per cent of adolescent girls suf-         to sunlight, and cannot synthesise enough              previously, there are specific disorders
fer from iron-deficiency anaemia.6 The                vitamin D. This results in impaired absorp-            directly linked to vitamin deficiency. Table 3
greater prevalence of deficiency in girls is          tion of calcium, which increases the risk of           shows the main food sources of vitamins and
associated with menstruation. If confirmed            osteoporosis. The Department of Health                 the effects of deficiency.3

 TABLE 3: VITAMINS — SOURCES AND EFFECTS OF DEFICIENCY
Vitamin                Source                                                           Effects of deficiency
A                     Liver, fish, liver oils, whole or fortified milk, eggs, carrots   Poor night vision or night blindness
                       and green leafy vegetables
B1 (thiamine)         Yeast, organ meats, peas, beans and wheat germ                    Fatigue, loss of appetite, weight loss, gastric upset
B2 (riboflavin)       Dairy products, meat, poultry, fish, enriched and fortified       Soreness of the mouth and tongue, burning and itching of the eyes,
                       grains, cereals and green vegetables (eg, broccoli, spinach)      increased sensitivity to light, loss of vision
B3 (niacin)           Meat, poultry, fish, enriched cereals, grains and nuts. Milk      Weakness, indigestion, skin inflammation and lethargy. Severe
                       and eggs contain little niacin but do provide trytophan,          deficiency results in scurfy skin, swollen tongue, tremors and
                       which is converted into niacin in the body                        damage to the central nervous system
B5 (pantothenic acid) Abundant in meat, poultry, fish and wholegrain cereals            Fatigue, heart and digestive problems, respiratory infections and,
                                                                                         if severe, lack of co-ordination
B6 (pyridoxine)        Chicken, fish, kidney, pork, eggs, soya beans, whole wheat       Depression, vomiting, increased susceptibility to disease and infection,
                        products and nuts                                               skin and nerve inflammation, anaemia, nausea and lethargy
B12                    Meat, poultry, fish, milk, dairy products and eggs               Pernicious anaemia and neurological problems
C (ascorbic acid)      Green and red peppers, greens, broccoli, spinach, tomatoes,      Damage to blood vessels, swollen, tender and aching joints, and general
                        potatoes, strawberries, oranges and other citrus fruits          weakness. A severe form is scurvy, which is characterised by anaemia,
                                                                                         tooth loss and bleeding under the skin and into joints
D                      Sunlight, fortified milk and margarine, eggs and butter          Bone changes leading to development of rickets in children and
                                                                                         osteomalacia in adults
E (tocopheryl)         Vegetable oils, margarine, nuts, wheat germ and green leafy      Anaemia in infants and nerve damage in adults
                        vegetables
K                      Sunlight, fortified milk and margarine, eggs and butter          Deficiency is rare but when present can lead to abnormal blood clotting
Biotin                 Liver, egg yolk, soya flour, cereals and yeast                   Skin inflammation, conjunctivitis
Folic acid             Found in many foods but as much as 50 per cent can be            Anaemia, digestive disorders, loss of appetite, weakness, heart
                        destroyed during cooking, food processing and storage.           palpitations and behavioural disorders
                        Rich sources include liver, yeast, and leafy green vegetables



15 September 2001                                    THE PHARMACEUTICAL JOURNAL (VOL 267)                                                                           353
       CONTINUING EDUCATION
       TABLE 4: — EFFECTS OF OVERDOSE 3                                                                          with a lower incidence of lung, colorectal and
      Vitamin                    Effects of overdose                                                             prostate cancers.13 hese results are exciting
      A                          High-dose supplements can be toxic and can affect almost every part of the      but need to be replicated before a public
                                  body, including the eyes, bones, blood, skin, central nervous system, liver,   health recommendation can be made. Some
                                  genitals and urinary tract. Severe toxicity can lead to blindness and might    parts of the United States and Canada are
                                  even be life threatening. Excessive dosage in children can lead to liver       considering fortifying flour with selenium.
                                  damage and adverse effects on the brain. In pregnancy, amounts not much        However, there is a moderate to high health
                                  higher than the RDA increase the risk of birth defects
                                                                                                                 risk from taking too much selenium. Toxicity
      B1 (thiamine)              No toxic effects have been reported
      B2 (riboflavin)            One new study has indicated that high consumption of vitamin B2 can             results in hair loss, gastrointestinal upset,
                                  increase the risk of stomach cancer                                            nerve damage, garlic odour on the breath and
      B3 (niacin)                Doses not much higher than the RDA can cause flushing of the face and           malfunctioning of the immune system.
                                  shoulders, itchiness and gastric problems. High doses can give rise to              Supplementation cannot be recom-
                                  ulcers, gout, diabetes and liver damage.                                       mended but it is probably worth noting that
      B5 (pantothenic acid)      No toxicity has been reported in humans but high doses have been found to       brazil nuts, walnuts and tuna are good
                                  cause liver damage in rats                                                     dietary sources of selenium.
      B6 (pyridoxine)            Pyridoxine reduces the effects of levodopa used for Parkinson’s disease.
                                  High doses can cause nerve damage, interfere with blood sugar levels and
                                  can influence the action of anticonvulsants                                    ADVERSE EFFECTS OF VITAMINS
      B12                        No toxic effects have been reported
      C (ascorbic acid)          High doses (more than 1g per day) can cause headaches, intestinal and           The total upper intake level of vitamins and
                                  urinary problems. High doses can interfere with anticoagulants, blood          minerals is defined as the maximum dose
                                  tests used in diabetes and stool tests for diagnosing colonic cancer           likely to be safe in nearly all individuals.
      D                          Prolonged high dosage can cause calcification of soft tissue and life-          Exceeding this dose can result in adverse
                                  threatening kidney failure                                                     effects, which are listed in Table 4. Excessive
      E (tocopheryl)             High doses can cause bleeding problems, particularly in people taking           doses of water-soluble vitamins are excreted
                                  anticoagulants                                                                 through the kidneys and are less likely to
      K                          Supplements can interfere with anticoagulant drugs and should not be taken
                                                                                                                 cause problems than their fat-soluble coun-
                                  by people on such drugs without first consulting a physician
      Folate                     High doses in the elderly can mask symptoms of vitamin B12 deficiency           terparts.
      Choline                    This has recently been recognised as an important vitamin essential for
                                  foetal brain development. There is some concern that high doses can be         CONCLUSION
                                  carcinogenic
                                                                                                                 Vitamins and minerals are essential for
                                                                                                                 health. For most people, the necessary daily
      ANTIOXIDANTS                                         no evidence that antioxidant supplements              amounts can be obtained from a well bal-
                                                           will have a protective effect. The best way to        anced diet with adequate intake of fruit and
      Antioxidants comprise vitamins C and E,              achieve high levels of antioxidants is by eat-        vegetables.
      together with beta-carotene (the building            ing a balanced diet that includes at least five           There is good evidence of the benefits
      block for vitamin A) and certain minerals,           or six servings of fruit and vegetables every         of calcium and folate supplements in the
      such as selenium. They have been shown to            day.10,11                                             elderly, in women who are trying to become
      have a protective effect against cardiovascu-             Selenium is an essential trace mineral. It       pregnant and during the first 12 weeks of
      lar disease and certain cancers.                     is an important part of the antioxidant               pregnancy. However, for most people (other
           During the process of oxidation there is        enzymes that protect cells from the harmful           than those on restricted diets), supplement-
      a release of free radicals. Antioxidants deac-       effects of free radicals. It is also essential for    ing the diet with vitamins and minerals is
      tivate these free radicals and thus give a           normal functioning of the thyroid gland and           not necessary and could potentially be
      degree of protection against heart disease           immune system. Several lines of scientific            harmful.
      and some cancers. Although it has been               inquiry suggest a link between low dietary                Pharmacists should advise people to
      shown convincingly that diets high in                concentration of selenium and an increased            concentrate on eating a healthy, well bal-
      antioxidants (eg, the Mediterranean diet             risk of cancer.12                                     anced diet and to await further official
      with its high proportion of fruit and vegeta-             A 10-year trial has suggested that supple-       advice before resorting to dietary supple-
      bles) have a protective effect, there is, as yet,    mentation with selenium could be associated           mentation.



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354                                                       THE PHARMACEUTICAL JOURNAL (VOL 267)                                              15 September 2001

				
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