Travelers visiting many tropical, sub-tropical and developing countries run an increased risk of suffering a gastrointestinal illness. These are usually caused by bacteria, parasites and viruses. The microscopic bugs at the top of these rather gut wrenching (for all the wrong reasons...) charts are E Coli, the staphylococci, shigella and salmonella species, campylobacter jejuni, cryptosporidiosis, and hepatitis A.
Infected food is the biggest culprit, with water coming in second. Ice cream, cocktails served in re-used coconut shells, raw seafood, ice, and food from street vendors are potential risks that can interrupt your adventure with less salacious memories to pass on to family and friends.
The nausea, stomach cramps and diarrhea from such acute infections usually sorts itself out after a few days (unless of course you have contracted hepatitis A, or something like giardia). Certainly, if you are unlucky enough to be sick after a few days, you should see a doctor.
Fortunately, there are remedies you can take that will strengthen your immune and digestive system and hopefully give your body a better chance at dealing with its new environment. The herbs I describe below would make an excellent travelers mix. The best form to take them in would be as a tincture, which can be made up by going to a local herbal dispensary if you have one in your area, or alternatively, a local herbalist.
Astragalus (Astragalus membranaceus)
Astragalus is a good anti-viral, anti-bacterial, and anti-microbial. The polysaccharides in it support the immune system. Astragalus increases the activity of phagocytes, natural killer cells, and the levels of antibodies in the blood.
Picrorrhiza (Picrorrhiza kurroa)
This is an Ayurvedic herb that is best given in low doses, as higher doses can cause diarrhea and flatulence in more sensitive people. Its a bitter herb, so it stimulates the digestive system. It is also anti-malarial, supports the immune system, and protects the liver. Picrorrhiza encourages all aspects of the immune system, such as B and T cell activity, and the activity of phagocytes. This herb is used in Ayurvedic medicine for liver related problems and immune problems.
Goldenseal (Hydrastis Canadensis)
Goldenseal is a gut antibiotic, which for example helps reduce adhesive e coli, and encourages some immune functions of the body. For example, berberine, which is one of its active constituents, has been shown to increase the activity of macrophages, which digest bacteria and viruses. Barberry also contains berberine, so more information on this very valuable constituent is below. Goldenseal, being a bitter herb, it is also good for the digestive system. If you are pregnant or suffer from hypertension, however, you should not take goldenseal.
Barberry (Berberis Vulgaris)
Berberine, one of the active constituents in this herb is an anti protozoic, which helps protect travelers against giardia, leishmania, and treponema pallidum. Other notable effects of berberine are its activity against giardia, dysentery, and candida, as well as the cholera vibrio. The active constituents berberine and palmatine are also anti-bacterial. And berbamine, which like berberine is an alkaloid, is a strong anti-bacterial which seems to work by increasing white blood cells and platelets. The constituent palamtine is a uterine stimulant, however, and as such pregnant women shouldn't take this herb. Barberry is another gut antibiotic, but it is also anti-malarial (though no self-respecting herbalist would recommend anything other than doctor's treatment if you do contract malaria).
Echinacea (Echinacea purpurea or augustifolia)
Echinacea is an immune stimulant. Its main active constituents are the polysaccharides and the alkamides (especially the isobutylamides), which are both immune stimulating, and the polyaceytlenes, which are antibacterial, anti-viral, and anti-fungal. Echinacea supports the activity of phagocytes, which are part of the immune system, and is also considered anti-viral and anti-microbial. One of the ways echinacea appears to work is by inhibiting the action of the enzyme hyaluronidase. This enzyme is used by micro-organisms to break down the connective tissue that prevents them from entering and spreading through the body. For these reasons, it is excellent as part of a travelers remedy mix.
These remedies are not designed as a prophylactic, like a vaccine. They work on the principle of giving your body an increased chance at staying healthy. But nothing replaces common sense. Wash your hands before eating. Don't drink ice or from water bottles where the seal has been broken. Drink cocktails in glasses, not cute but probably old coconut shells. Don't eat anything fresh that you can't peel. Don't eat ice cream or drink unpasteurized milk. Be wary of eating from street vendors. Some people do, and are fine. But they are a risk factor with gastrointestinal upsets. Its a good idea to pack some oral hydration salts as a precaution.
But above all, enjoy your holiday!
References: C Fisher & G Painter, Materia Medica of Western Herbs for the Southern Hemisphere
Class notes from Ses Salmond, certified Natural Therapist and Herbal Medicine teacher