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Open Access Publications from the University of California

Nutrition Noteworthy

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Gaining Weight From Nighttime Munchies: Circadian Rhythms, Feeding, and Metabolism

Possible circadian cyclicity in both feeding behavior and in metabolic responses to food may contribute to the purported tendency toward weight gain of individuals who eat primarily at night. Investigation into both physiological and metabolic correlates to feeding and energy utilization revealed that leptin, a satiety hormone, is not regulated in circadian fashion. Diet-induced thermogenesis showed a strong circadian rhythm, with increased thermogenesis in the day. Insulin sensitivity and plasma glucose levels, as well as growth hormone levels, also have circadian rhythms which may be modified slightly but not appreciably disrupted by sleep and activity pattern changes.

The Epidemiology of Malnutrition in Disasters

Despite the public’s perception, widespread malnutrition following disasters is not common. The disasters that are most likely to result in significant malnutrition are those that occur in developing nations and that destroy or restrict access to major food supplies. Both protein-energy malnutrition (PEM) and micronutrient malnutrition can occur. PEM occurs when the diet lacks sufficient calories and protein to meet daily needs. Common types of micronutrient malnutrition seen in disasters are deficiencies of Vitamin A, Vitamin C, Iron, and Niacin. Both types of malnutrition often take several weeks or months to develop. Certain diseases such as diarrhea and measles can promote malnutrition due to impaired absorption of nutrients. Particularly vulnerable populations include families headed by women, unattended children, the elderly, and pregnant or lactating women. Measures to prevent malnutrition following a disaster include assuring that emergency food supplies are nutritionally complete, that food is distributed equitably among the affected population, that safe drinking water is available, that adequate sanitation is maintained, and that diseases which promote malnutrition are controlled.

Tofu After 50: Dietary Soy and Its Role in Hormone Replacement After Menopause

The importance of estrogen action in maintaining health is illustrated by the increase in incidence of many disorders after the loss of circulating estrogen which accompanies menopause. Serious health and economic costs are incurred by the increased rates of heart disease, osteoporosis, vasomotor symptoms (hot flashes) and other disorders. Although the risk of these diseases may be reduced by the administration of replacement hormones, many women elect not to begin or to continue hormone replacement therapy (HRT). This may be due in part to concerns about increased risk of cancer and of other diseases whose association with HRT is uncertain. Epidemiologic studies show decreased risk of some of these syndromes and symptoms in populations whose intake of phytoestrogen-containing foods is significant. Since these dietary compounds show some estrogenic activity, controlled studies have been carried out to examine the relationship between intake of isoflavones, the most metabolically active of these phytoestrogens, and the disorders associated with menopause. There appear to be some significant benefits of isoflavones after menopause, without the increased risks of cancer which may be associated with traditional hormone replacement.

A Pediatrician's Guide to Infant Dental Hygiene: Focus on Fluoride and Nutrition

As future pediatricians some of us will be asked seemingly benign questions, the answers to which are not simple and are mired in current public health controversy. One of these questions will be about dental hygiene for infants. This paper poses some common questions parents may ask, and attempts to provide the information necessary to provide the best answers possible. Plaque is a buildup of microorganisms that produce acid as a byproduct of sugar metabolism. This acid demineralizes the tooth's enamel; fluoride slows acid production and provides the substrate for remineralization. Development of caries depends on the relative rates of de- and remineralization. Los Angeles' water supply is unusual for a major city in the US because it contains amounts of fluoride well below the optimal levels recommended by public health officials (1.0 ppm). Despite the low fluoride content, fluoride supplementation for infants is not recommended by the American Academy of Pediatrics due to evidence of dental fluorosis (mottling of teeth) after exposure to excess fluoride. The clearest recommendations for parents of infants are to only provide sweets at mealtimes, including sweetened beverages, and to brush their children's teeth with a low fluoride toothpaste as soon as the teeth erupt.

Effects of Omega-6 and Omega-3 Polyunsaturated Fatty Acids on Breast Cancer

Epidemiological observations reveal that Japanese women, who eat a low-fat diet with a high fish consumption, have a much lower incidence of breast cancer than North American and European women who eat a higher fat diet rich in omega-6 polyunsaturated fats. This observation has been supported by experimental research that omega-6 fatty acids like corn and safflower oil can promote tumor growth, and omega-3 fatty acids found in fish oil can inhibit tumor growth. Omega-3 fatty acids serve a protective role against breast cancer by competitively inhibiting harmful omega-6 metabolites that may be responsible for tumor promotion. This research holds promise for possible clinical applications including breast cancer risk screening, dietary prevention, and therapeutic dietary intervention for breast cancer patients.

Green Tea and Its Antioxidant Properties

Green tea contains antioxidants which have been implicated to contribute to reduced risk of cardiovascular disease. This may be explained in part by the green tea's antioxidant properties. Green tea is a rich source of flavonoids with high antioxidant activity both in vitro and in vivo. This includes the ability of green tea to lower the oxidizability of low-density lipoprotein (LDL) in vitro. In vivo lipid oxidation as measure by plasma lipid peroxides and LDL oxidizability are significantly decreased by green tea. Green tea consumption tends to reduce aortic lesion formation by 31%. In addition, green tea induces a prolongation of the lag phase with a corresponding diminution of oxidation rate. This also reduces the probability of red blood cell hemolysis. However, conflicting results also exist that nullify the antioxidant benefits of green tea in vivo.

Alcohol and the Asian Glow

Facial flushing is a common hypersensitivity reaction that may be observed in many Asians following low to moderate alcohol consumption. Flushing can be accompanied by other symptoms such as tachycardia, nausea, and dizziness. Recent studies have shown that this flushing reaction is due to the presence of ALDH2*2, an inactive allele for the alcohol dehydrogenase gene found in approximately 50% of Asians. Aldehyde dehydrogenase (ALDH) is an important enzyme in alcohol metabolism, and deficiency of that enzyme causes the accumulation of acetaldehyde. It is suggested that acetaldehyde mediates the flushing reaction by directly inducing mast cell release of histamine, although increased levels of catecholamines and IgE antibodies against acetaldehyde-protein adducts may play a role as well. Studies also demonstrate that carriers of the ALDH2*2 allele tend to consume lower amounts of alcohol and have lower incidences of alcohol abuse than non-carriers. These findings may explain the reduced frequency of alcoholism and alcohol consumption among Asians relative to Caucasians and other non-Asian minorities, groups in which the ALDH2*2 allele is rare.

Is Withholding Moderate Wine Intake Recommendations as a Secondary Treatment for Patients with Cardiovascular Disease Ethical?

Alcohol has been used as a medicine for centuries. In many studies, alcohol, specifically wine, has been shown effective in reducing mortality rates for patients with cardiovascular disease. With this in mind, one might question if it is ethical for physicians to withhold moderate wine intake recommendations for patients with cardiovascular disease. This paper discusses the ethical obligations a physician should meet in selecting patient treatment, health benefits of moderate alcohol intake for cardiovascular disease patients, as well as harmful effects of alcohol consumption. Further, risk factors and screening questionnaires for alcohol dependency are presented in relationship to physician liabilities for alcohol abuse neglect in their patients.