And here's the kicker: about 70 per cent of adults are lactose-intolerant (Gastroenterology, 1971; 61: 805-13).
Without lactase, lactose cannot pass through the gut wall into the bloodstream. This accumulation of undigested sugar causes gut bacteria to switch to lactose metabolism, resulting in abdominal symptoms such bloating, flatulence, cramps and, sometimes, diarrhoea. Any unabsorb-ed lactose also prevents the colon from reabsorbing water.
The incidence of adult lactose intolerance is lowest in the northern countries-2 per cent among Swedes and 5 per cent among Danes-and increases the nearer to the equator, with the highest rates found among Australian Aborigines (85 per cent), Thais (98 per cent) and Native Ameri-cans (100 per cent). This may be an example of a evolutionary adaptation to allow for absorption of vitamin D from milk products where sunshine is weakest. The exceptions are, however, Alaskan Inuits (80-per-cent intoler-ant), who have traditionally obtained much of their vitamin D from fish oils.
The hydrogen breath test is generally used to assess lactose intolerance. After an overnight fast, 50 g of lactose (dissolved in water) are swallowed. If the lactose cannot be digested, enteric bacteria will metabolize it instead and produce hydrogen. This gas can be detected in the patient's exhaled breath after about three hours.
Also, blood glucose can be measured every 30 minutes after lac-tose ingestion, and will show a 'flat curve' in lactose malabsorption.
In contrast, in those who aren't lactose intolerant, there will be a 'significant top', with a typically 50- 100-per-cent rise over a two-hour period.
Children infected with Ascaris lumbricoides, the largest and most common type of roundworms (which can be up to 40 cm in length), may become lactose-intolerant due to decreased gut-mucosal lactase activity (Parasitology, 1980; 81: 221-3).
It can also be caused by exposure to intestinal parasites such as Giardia lamblia. In such cases, lactose produc-tion may be permanently disrupted (Am Fam Physician, 2002; 65: 1845-50).
The curdling process has an impact on which foods may be tolerated. This is because lactose is found in the water portion of milk, along with whey and casein, but not in the fat portion-so there is little lactose present in, say, Emmenthaler cheese. On the other hand, dairy products that are 'fat-reduced' or 'fat-free' have a higher lactose percentage. In addition, low-fat dairy foods often contain added dairy derivatives, such as milk solids, to enhance sweetness, which will further increase the lactose content.
Foods with a high lactose content are known to promote intestinal candidiasis (Pizzorno JE Jr, Murray MT, Joiner-Bey H. The Clinician's Handbook of Natural Medicine. London: Churchill Living-stone, 2002: 121) and bacterial gut dys-biosis, where the normal intestinal flora become imbalanced due to 'unfriendly' bacteria and other micro-organisms, resulting in excessive bacterial fermentation in the gut.
The percentages of lactose present in various milks are:
- Human milk 9.0%
- Mare's milk 6.6%
- Yak's milk 4.9%
- Buffalo's milk 4.8%
- Cow's milk 4.7%
- Ewe's milk 4.6%
- Goat's milk 4.1%.
Plant-based milks and creams (such as soy milk, almond milk, rice milk, oat milk and cashew cream) are 100-per-cent lactose-free. HYLA (which stands for 'hydrolyzed lactose') is produced in Finland from cow's milk and is also virtually completely free
In the UK, manufacturers and distributors of lactose-free foods include Granose Foods, Welfare Foods, The Cantassium Company, Hockworthy Foods, van den Berghs and J"urgens, Meridian Foods, and Life and Health Foods.
The consumption of Lactobacillus acidophilus by people with lactose intolerance has been found to consistently improve their digestion (J Dairy Sci, 1983; 66: 959-66).
Acidum butyricum (obtained from butter) has had its homeopathic symptomatology established in a well-controlled pathogenetic trial, or 'homeopathic proving', in 1949 by Dr W.B. Griggs (Griggs WB. Butyricum acidum, in The Homoeopathic Recorder, 1964; pages 110-5). In my own practice, I have used it in two patients at low potencies, both times successfully: one was a case of lactic dyspepsia with reflux oesophagitis in a nine-year-old boy; the other was a man with adult lactose intolerance.
Supplementing with the lactase enzyme may be an option when lactose avoidance is not possible or is undesirable. The enzyme, called beta-galactosidase, is readily available in pharmacies (without prescription) in tablet form. Supplementation may
be preferable to avoiding dairy as that means that alternative sources of calcium will not be required, which is especially important for children (Paediatrics, 2006; 118: 1279-86).
Harald Gaier, a registered naturopath, osteopath, homeopath and herbalist, practises at The Allergy and Nutrition Clinic, 22 Harley Street, London, and the Irish Centre of Integrated Medicine, Co. Kildare (www.drgaier.com).