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A process is underway to introduce the concept of nutritional genetics into the health care system. Dieticians are trained countrywide to design diets that are based, in part, on genetic information and an increasing number of genetic counselling facilities are established in different regions in South Africa.
This was announced by geneticist Dr Maritha Kotzé of Genecare Laboratory at the Christiaan Barnard Memorial Hospital in Cape Town.
The laboratory provides an extensive support system that empowers health care professionals to apply genetic principles in everyday medicine. To better explain this concept to supporting doctors, many meetings have been scheduled over recent months at different hospitals and lecturing will continue into 2004.
Gene-diet and gene-drug interactions
Geneticists and dieticians at the Christiaan Barnard Memorial Hospital in Cape Town have recognised the potential usefulness of gene-diet and gene-drug interactions to reduce cancer risk in the general population. The Netcare dieticians have formulated guidelines on how one’s diet can be reshaped for best clinical outcome, while the geneticists have developed new tests that target common genetic risk factors.
These gene variations may increase cancer risk if dietary requirements are not met, but they do not cause cancer by themselves. Both the nutrition intervention and the genetic testing are important on their own, but together they become very powerful, the addition of the genetic component allows an individualised approach in many cases.
All the genes tested are involved in metabolic processes, which when they interact with unhealthy lifestyle factors (e.g. diet, smoking, inactivity, obesity), may increase an individuals susceptibility to cancer. By understanding how nutrients in the diet are able to compensate for specific gene limitations and may affect cancer risk, personalised health recommendations can now be formulated for individuals who choose to have their DNA tested.
DNA tests and breast, ovarian and colon cancer
Genetic testing is already used routinely to identify gene defects associated with a high risk for breast, ovarian and colon cancer in families. With this knowledge and appropriate guidance, individuals can make better decisions with regards regular check-ups or pro-active treatment, while those without the gene defect causing cancer in the family can be reassured that their cancer risk is reduced to that of the general population, according to Dr Maritha Kotzé, geneticists at Genecare Laboratory.
To reduce the incidence of cancer in the population
Gene defects screened for in these tests may increase the risk for cancer by up to 90%, but they are relatively rare and provide useful information in less than 10% of patients with cancer. With the newly developed DNA-diet tests it has now become possible to screen the general population for genetic risk factors that can be targeted by the avoidance of environmental triggers and the implementation of a personalised dietary plan.
The aim of which is to reduce the incidence of cancer in the general population.
DNA for heart disease
The DNA-diet test concept has already been successfully introduced into the health care system in providing a Cardiovascular Genetic Screen. Most medical aids are paying for this test, which includes a nutrition and lifestyle assessment and appropriate health recommendations.
The DNA test requires a cheek swab or blood sample and written informed consent by the patient.
The purpose of the nutri-gene tests is to identify areas in the diet and lifestyle that need to be addressed within the context of all other known risk factors, also taking into account any clinical features and family history relevant to the condition.
The cost of the tests depends on which heart disease or cancer types are targeted, and this is based on family history and personal health status. The dietary assessment and health recommendations provided with the genetic test result provide valuable information at no additional cost.
Folate in the diet can prevent heart disease in some people
One example of a nutri-gene test involves a gene-diet interaction that is regarded as a risk factor for both cardiovascular disease and cancer. There is a clear relationship between how much folate is available from the diet and a gene variation involved in this process. When the gene variation is identified and dietary intake of folate, and vitamins B6, B12 and riboflavin are inadequate, a persons’ DNA may be adversely affected, and homocysteine levels may be raised.
Since more than 20% of South Africans have this gene variation there is an opportunity for dietary intervention to contribute to the reduction of various types of cancer in a large proportion of the population.
Different studies
Studies of different diet-gene interactions have shown that what is sufficient for most people in the population may not be adequate for the individual when a specific gene variation is present. By identifying these gene variations and by working with a doctor and dietician to ensure the best diet and lifestyle choices, risk of many chronic diseases can be reduced. It is known that a healthy diet can reduce the incidence of both cancer and cardiovascular disease by 30 – 40%. Combining nutrition and genetics as part of a multidisciplinary approach can be expected to best motivate people to adapt a life-saving lifestyle.
In support of breast cancer awareness, Genecare will donate 10% of all income generated through cancer genetic testing in November 2003 to the University of Stellenbosch for breast cancer research.
For information on which tests are available, call the GeneCare laboratory (021) 422 5538 or (021) 480 6503 or email info@genecare.co.za
