Refusing Technology, Accepting Death: My Father's Story.

As the use of medical technology has increased near the end of life, new challenges have arisen regarding the dying process. Prior to the development of medical devices that sustained life, people held a more circumspect view of mortality because there was no other choice. Legitimate questions should be raised about the potential overuse of medical technology, and this may be applicable to implantable cardioverter defibrillators (ICDs). ICDs are used to correct potentially fatal arrhythmias, but one question that has been inadequately addressed is whether implanting such a device should, at some point, be considered too burdensome despite limited benefit. ICDs ought to be reconsidered under the circumstance of advanced age, and the challenges related to health literacy, acceptance of death, and resource allocation related to this technology must be addressed to avoid burdensome cardiac care that does not improve the quality of life.

Nutritional genomics and dietetic professional practice.

Nutrigenomics is concerned with the role of nutrients in gene expression, and nutrigenetics is the study of how genetic variants or polymorphisms (mutations) can affect responses to nutrients; nutritional genomics is the umbrella term. Nutritional genomics can be expected to revolutionize the way dietitians and other health professionals identify people with chronic diseases and treat those diseases. Understanding the science of nutritional genomics is important to dietitians and other health professionals because major scientific advancements such as this usually have a significant impact on ethics, policy, and practice. Blood lipid profiles are one area in which nutritional genomics has quickly advanced knowledge. New knowledge is available on blood lipid profiles and associated conditions, such as obesity and type 2 diabetes. New technology has also had an impact on policy and practice issues, and ethics is an important issue to consider.

Vitamin B12 and health.

OBJECTIVE: To review recent evidence that suggests vitamin B12 is associated with risk reduction for some chronic diseases and birth defects. QUALITY OF EVIDENCE: A MEDLINE search from 1999 to 2007 was performed using the key word vitamin B12. The most relevant articles (129) dealt with cardiovascular disease, cancer, mental health, and birth outcomes;most studies presented level II evidence. MAIN MESSAGE: Vitamin B12 might confer health benefits; however, such benefits are difficult to ascertain because of the complementary functions of vitamin B12 and folic acid. Vitamin B12 might lower high homocysteine levels below a threshold level achieved by folic acid alone. Furthermore, the interactions between the nutritional environment and genotype might have an important influence on vitamin B12, chronic disease risk, and risk of neural tube defects. CONCLUSION: Vitamin B12 might help protect against chronic disease and neural tube defects, but more research, particularly in the area of nutritional genomics, is needed to determine how vitamin B12 might augment the benefits of folic acid. Some consideration should be given to the potential value of fortifying foods with vitamin B12 in addition to the current mandatory folic acid fortification of grains.

Folic acid and prevention of neural tube defects.

QUESTION: Now that flour and pasta have been fortified with folic acid in Canada, do I still need to recommend folic acid supplements to my patients who are of child-bearing age? If I should recommend supplements, when should I recommend them, and what is an appropriate dose? ANSWER: Non-pregnant women should consume 400 microg of folic acid daily, and pregnant women should consume 600 microg of folic acid daily. Mean intakes of folate in Canada before fortification were around 200 microg/d or less. Fortification increased intake of folic acid by up to 100 microg/d. You should discuss the importance of folic acid with your patients who are planning pregnancy; it is recommended that a folic acid supplement or prenatal multivitamin containing at least 400 microg of folic acid be consumed daily. The upper limit for folic acid is 1 mg/d. Women in intermediate- to high-risk categories for neural tube defects, such as a previous neural tube defect-affected pregnancy, should take 4 to 5 mg of folic acid daily.

Diet and colorectal cancer: Review of the evidence.

OBJECTIVE: To investigate whether diet has a role in the development and progression of colorectal cancer (CRC). QUALITY OF EVIDENCE: MEDLINE was searched from January 1966 to December 2006 for articles on the relationship between diet and CRC using the key words colorectal cancer and folic acid, calcium, vitamin D, red meat, or fibre. Evidence that these factors are associated with CRC came from case-control and prospective cohort studies and some clinical trials. MAIN MESSAGE: Whether red meat is a culprit in causing CRC remains unanswered, although any effect it might have is likely moderate and related to processing or cooking. The effect of dietary fibre on risk of CRC has also been difficult to determine because fibre intake is generally low. Evidence that folic acid, calcium, and vitamin D reduce risk of CRC is stronger. In particular, recent research indicates that calcium and vitamin D might act together, rather than separately, to reduce the risk of colorectal adenomas. There might also be an interaction between low folate levels and high alcohol consumption and CRC. CONCLUSION: Before dispensing dietary advice, physicians should understand the potential benefits and harm of specific components of various foods. People might be able to reduce their risk of CRC by increasing their vitamin and mineral levels through eating more vegetables and fruit. Multivitamin and mineral supplements can complement a healthy diet.

Carpal tunnel syndrome and vitamin B6.

QUESTION: A 42-year-old woman with carpal tunnel syndrome tells you she has started taking a vitamin B6 supplement to relieve her symptoms. Her work in an automotive parts department involves both lifting moderately heavy packages and typing at a computer terminal. What does the research indicate about vitamin B6 as a treatment option, and what health issues should you discuss with this patient? ANSWER: Although its effectiveness is controversial, vitamin B6 is often used as a conservative and adjunct therapy in treatment of carpal tunnel syndrome. Many patients attempt to treat their symptoms with vitamin B6 on their own. Vitamin B6 at less than 200 mg daily is not likely to cause any adverse effects, but patients should be monitored for changes in symptoms, particularly when high doses are taken over long periods.

The relevance of selenium to immunity, cancer, and infectious/inflammatory diseases.

Selenium is an essential trace element involved in several key metabolic activities via selenoproteins, enzymes that are essential to protect against oxidative damage and to regulate immune function. Selenium also may have other health benefits unrelated to its enzymatic functions. It may provide important health benefits to people whose oxidative stress loads are high, such as those with inflammatory or infectious diseases like rheumatoid arthritis or human immunodeficiency virus/acquired immunodeficiency syndrome, or who are at high risk for cancers, particularly prostate cancer. Some studies have generated compelling evidence that selenium is beneficial, either alone or in conjunction with other micronutrients. Additional data from large clinical trials that provide the highest level of evidence will be key to determining the benefits accrued at various selenium intake levels. When the strength of the evidence becomes sufficient, clinical health professionals will need to use dietary and clinical assessment methods to ensure that people at increased risk for cancer or inflammatory and infectious diseases can be appropriately advised about selenium intake.

Bone health. New role for vitamin K?

OBJECTIVE: To assess growing evidence that vitamin K (phylloquinone) plays an important role in bone health and, subsequently, in prevention of osteoporotic fractures. QUALITY OF EVIDENCE: We searched MEDLINE from January 1972 to December 2002 using the key words vitamin K and bone health. We reviewed 30 articles that seemed relevant or had a human focus. All evidence can be categorized as level II. MAIN MESSAGE: Evidence suggests that dietary phylloquinone intake of <100 microg daily might not be optimal for bone health. Low intake of vitamin K could contribute to osteoporosis and subsequent fracture due to the undercarboxylation of osteocalcin. CONCLUSION: Family physicians need to be aware of the importance of encouraging adequate vitamin K intake, particularly among institutionalized elderly people, to prevent increased bone resorption. Further study is needed to determine the exact role of vitamin K in bone metabolism, and methods of assessing vitamin K requirements need to be standardized.

How diet and lifestyle affect duodenal ulcers. Review of the evidence.

OBJECTIVE: To demonstrate the role of diet in reducing or aggravating risk of duodenal ulcer (DU). QUALITY OF EVIDENCE: MEDLINE was searched from January 1966 to December 2001 for articles on the relationship between diet and lifestyle and DU using the key words duodenal ulcer and diet, fibre, or lifestyle. Evidence that these factors are associated with DU arose mainly from three case-control and three prospective studies (level II evidence) and from expert opinion (level III evidence). MAIN MESSAGE: A high-fibre diet appears to reduce risk of DU; soluble fibre might be associated with reduced risk also. Vitamin A intake is associated with lower risk of DU. Little evidence indicates that fat, type of fat, protein intake, or consumption of alcohol or caffeine affect the etiology of DU. CONCLUSION: A high-fibre diet, particularly if the fibre comes from fruit and vegetables, could reduce risk of DU; vitamin A might also be beneficial.

Preventing diverticular disease. Review of recent evidence on high-fibre diets.

OBJECTIVE: To review recent evidence on dietary factors associated with diverticular disease (DD) with special emphasis on dietary fibre. QUALITY OF EVIDENCE: MEDLINE was searched from January 1966 to December 2001 for articles on the relationship between dietary and other lifestyle factors and DD. Most articles either focused on dietary intervention in treating symptomatic DD or were case-control studies with inherent limitations for studying diet-disease associations. Only one large prospective study of male health professionals in the United States assessed diet at baseline and before initial diagnosis of DD. MAIN MESSAGE: A diet high in fibre mainly from fruits and vegetables and low in total fat and red meat decreases risk of DD. Evidence indicates that the insoluble component of fibre is strongly associated with lower risk of DD; this association was particularly strong for cellulose. Caffeine and alcohol do not substantially increase risk of DD, nor does obesity, but higher levels of physical activity seem to reduce risk of DD. CONCLUSION: A diet high in fibre and low in total fat and red meat and a lifestyle with more physical activity might help prevent DD.