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Australian Journal of Pharmacy : November 2006
complement complementary medicine Lesley Braun, BPharm, DipAppSci, Phytotherapy, independent technical consultant to Mayne Consumer Products and PhD candidate (RMIT) School of Health Sciences Food, supplements as medicine ‘L ET food be your medicine and med- icine be your food’ is a saying attrib- uted to Hippocrates, widely considered the father of Western medicine. In the 5th century, this renowned philosopher and physician observed that some foods potentially cured and prevent eddisease whereas others eaten in insuffi- cient quantities, or to excess, could cause health problems. This idea largely went ignored until Lind recognised citrus fruits as both the prevention and cure for scurvy in the mid 1700s. In the early 20th century, Linus Paul- ing and Victor Rocine renewed people’s interest in the therapeutic value of food and its varied effects on health and dis- ease, and now there is significant scientific agreement that diet plays an important role in health.1 Chemically complex cocktails Similar to herbal medicines, foods are chemically complex cocktails. They are made up of macronutrients (such as car- bohydrates, sugars, fats and water), micronutrients (such as vitamins and min- erals) and a group of constituents known as phytochemicals which don’t fall into either category, but may still have impor- tant health-promoting qualities. Food can also contain natural or synthetic additives (for example preservatives) and contami- nants (for example environmental pollu- tants). Therefore, the food we ingest has the potential to influence many biochem- ical pathways and is much more than just a vehicle for macro and micronutrients. Of note, there has been much recent scientific interest in phytochemicals. These are plant components which appear to provide significant health ben- efits but are considered non-essential to humans. Some of the better known ones are isoflavones (for example genistein and daidzein), flavonoids (for example in grapes, tea and wine), allyl sulphides (in onions and garlic) and carotenoids (in corn, spinach and tomatoes). Considerable research has been under- taken to understand the role they play in maintaining health and preventing cer- tain diseases such as cancer, heart disease, diabetes and macular degeneration, how- ever, there is still much to uncover. Not surprisingly many of the phytochemicals found in foods are also found in medici- nally used herbs and partly explain their therapeutic effects. Whole foods vs supplements The myriad of components found in foods means that interactions will undoubtedly occur between ingredients. Supplement- ing a diet with individual food compo- nents may produce different effects to the consumption of the whole food. For example epidemiological studies supporting the use of foods containing ß- carotene for the prevention of lung can- cer in smokers have not been supported by clinical trials of supplementation with synthetic ß-carotene. There is strong evi- dence to suggest that eating a variety of fibre-rich foods is beneficial in the pre- vention and management of diabetes, however, studies using fibre supplements have produced contradictory results.2 Over the last decade, investigation into the effects of various tocopherols found naturally in food have suggested that they have stronger pharmacological effects when combined, as in food, than when isolated d-alpha tocopherol is used alone. For example, preliminary studies using different mixtures of tocopherols have found that a mixture of gamma-, delta- and alpha-tocopherol with the ratio of 5:2:1 has a much better antioxidant effect than alpha-tocopherol alone, more favor- able effects on constitutive NO synthase (ecNOS) and superoxide dismutase activ- ity, and are more effective in decreasing platelet aggregation and inhibiting thrombus formation.3,4 Mixed tocopherols are also superior to alpha-tocopherol in terms of myocyte protection.5 56 ? THE AUSTRALIAN JOURNAL OF PHARMACY VOL.87 NOVEMBER 2006 These observations may partly account for the generally positive correlations seen with vitamin E rich foods and reduced risk of cardiovascular disease and the inconsistent results seen with vit- amin E supplements. Recent preliminary studies show that quercetin, a ubiquitous flavonoid found in numerous fruits and vegetables, inhibits P- glycoprotein (P-gp,)6–8 CYP1A19 3A46 and CYP activity. As a result, when quercetin is present in foods that contain substrates for these proteins, an interaction occurs and, theoretically, serum levels of these substrates can rise. Some investigation into quercetin-induced interactions has focused on medicinal herbs and this may partly explain batch to batch differences in their pharmacological effects. Nutrient absorption Not all interactions between food compo- nents will produce beneficial effects. As an example, consider the bioavailability of the mineral zinc from food. Zinc is an essential trace element known to play an important role in all human living cells. Dietary intake of zinc by healthy adults is 6 to 15mg/day, but less than half of this is absorbed10 as zinc absorption is influ- enced by many factors and adequate dietary intake is not necessarily indicative of adequate zinc status. Foods with high phytate content (for example whole- grains, corn and rice) significantly reduce zinc absorption due to the formation of strong and insoluble complexes.11 Concerns have also been raised over the potential of calcium, iron, copper and cadmium to reduce zinc absorption. Alternately, the amount of animal protein in a meal positively correlates to zinc absorption and the amino acids histidine and methionine, and various organic acids present in foods, such as citric, malic and lactic acids, can also increase absorp- tion. As such, zinc is best absorbed from ani- mal food sources or taken as a supplement on an empty stomach.