Food Choices
The percentage of fat by weight is widely used on food labels and advertising. Although this information is correct, it is misleading to the American public. The recommendation that fat intake should be limited to 35% refers to the percentage of fat based on the total kilocalories of the product. As shown below, the percentage of fat in whole milk is 49% of the total kilocalories, not 3.25% as the label indicates.
The Nutrition Facts Label on foods indicates the grams and % Daily Value for fat, saturated fat, and trans fats in a serving of the food. All trans fats, including those from ruminant animals, are included on the Nutrition Facts Label; only CLAs are excluded. In 2003, before trans fats were added to the nutrition label, average consumption was 5.8 g, or 2.6% of kilocalories. Because a specific amount of trans fats has not been recommended, consumers find it difficult to interpret whether the product contains a high level or not. Even a motivated consumer may misinterpret a label indicating 4 g of trans fats as being acceptable. A claim such as “zero” trans fat is more helpful than the information on the Nutrition Facts Panel. The AHA recommends less than 2 g of trans fat daily, but zero trans fat intake is best. The Nutrition Facts Label may indicate the product has no trans fats, but the ingredient label indicates “partially hydrogenated” oil. This is because the U. S. Food and Drug Administration (FDA) allows manufacturers to label a food as “zero” trans fats if the product contains less than 0.5 g per serving. Canadian regulations set the labeling threshold at 0.2 g per serving.
For most people, a decrease in red meat sonsumption is probably desirable, but the decision to eliminate it completely from the diet is not adviseble. In recent years, through improvements in breeding and feeding livestock, these products are lower in fat, saturated fat, kilocalories, and cholesterol. Other important nutrients are present in beef, pork, and lamb; moderate use of these products is encouraged for everyone. Loin (sirloin, tenderloin, or center loin) and round cuts (top, bottom, eye, or tip) and lean or extra lean ground beef contain the least amount of fat. More important than the fat content of a product is its saturated and trans fatty acid content.
Overconsumption and health-related problems
Some conditions related to fat intake are observed in dental hygiene practice. The following conditions suggest alteration of the amount or type, or both, of fat in the diet: obesity, diabetes mellitus, hyperlipidemia (elevated concentrations of any or all of the blood lipids, especially triglycerides and LDL cholesterol), fatty infiltration of the liver, and certain types of cancer.
Obesity
Excessive fat stores are a common disorder in the United States. Although the cause is usually oversonsumption of all energy nutrients, kilocalories from fat are so concentrated that relatively small quantities may rapidly increase caloric intake.
Blood Lipid Levels
Elevated blood lipids are related to diet. Hyperlipidemia is associated with heart disease. Although many factors can affect blood lipid levels, the strongest dietary determinant of the blood cholesterol level is the saturated fat content of the diet. Based on results of metabolic and epidemiological studies, trans fatty acids act like SFAs by increasing the risk of heart disease considerably and have a negative influence on blood glucose. Because of the unfavorable publicity about the harmful effects of trans fatty acids and food labels disclosing how much is in the product, commercial food producers have developed product alternatives to partially hydrogenated fats. Preserving the structural characteristics and palatability of these food products is not easy.
Many of the trans fatty acid alternatives, especially those made from tropical fats containing SFA, may not have a desirable effect on blood lipids. In some cases, the hydrogenation process has been modified to reduce the amount of trans fatty acid to less than 10% of the oil contents.
A process called interesterification produces customized fats with properties suitable for foodservice applications. Highly saturated hard fats are blended with oils to produce fats with intermediate characteristics. Some zero trans fat margarines may have a higher amount of SFA compared with conventional margarines with trans fatty acid. In short studies comparing the effects of trans fatty acid and interesterified fats, these new fats negatively affect blood lipids, but not as severely as trans fats. Needless to say, more research is needed to determine the potential consequences of the products being used to replace trans fatty acids.
In contrast, stearic acid, found in beef and cocoa butter, has no detrimental effect on serum cholesterol. Total fat content also affects serum lipid levels, but to a lesser extent. Reduction of the total dietary fat content may hepl reduce saturated fat content of the diet.
Cancer
Annually, 33% of the more than 500,000 deaths that occur in the United States because of cancer can be attributed to diet and physical activity. Research continues to examine whether the association between high-fat diets and various cancers is due to the total amount of fat, the particular type of fat, the kilocalories contributed by fat, or some other factor associated with high-fat foods. Diets high in fat also are high in energy and contribute to obesity, which has been associated with increased risk of cancer of the breast and ovaries, and possibly other sites. Evidence linking dietary fat and particular fatty acids with risk of cancer has elicited considerable interest and debate because of the diversity of findings. Different mechanisms may be involved in tumor development at different sites and stages of the cancer. Despite many uncertainties about a relationship between dietary fat and cancer risk, the cosensus of opinion is to limit total fat intake by increasing fish and lean meat consumption, while concurrently decreasing high-fat meats and foods.
Underconsumtion and health-related problems
Overconsumption of fat is a primary concern in health care, whereas underconsumption of fats is virtually nonexistent in the United States without medical or dietary intervention. However, clinical symptoms of fat deficiency may occur, especcially in patients with malabsorption syndromes such as cystic fibrosis or patients in later stages of AIDS. EFA deficiency results in poor growth, dermatitis, reduced resistance to infection, and poor reproductive capacity.
When overall food intake, including fats, is poor, patients lose weight, and the subcutaneous fat stores needed to maintain body temperature are depleted. Patients with anorexia nervosa are especially of concern.