Page 93 - Nutrition Essentials for Nursing Practice

C H A P T E R 4 Lipids 81

Fat Deficiency

Although the body cannot make essential fatty acids, it does store them, making deficien-
cies extremely rare in people eating a mixed diet. Those at risk for deficiency include infants
and children consuming low-fat diets (their need for essential fatty acids is proportionately
higher than that of adults), clients with anorexia nervosa, and people receiving lipid-free
parenteral nutrition for long periods. People with fat malabsorption syndromes are also at
risk. Symptoms of essential fatty acid deficiency include growth failure, reproductive failure,
scaly dermatitis, and kidney and liver disorders.

FAT IN HEALTH PROMOTION

For decades, fat has virtually been public health enemy number 1, blamed for causing heart
disease, cancer, and obesity. For years, eating no more than 30% of total calories from fat
was touted by various governmental and health agencies as the way to improve Americans’
health. It now appears that the message to eat less fat was too simplistic because it ignored
the different health effects produced by different types of fat. Multiple studies have shown
that the type of fat in the diet can affect serum lipids more than the total amount of fat
(Zarraga and Schwarz, 2006). Other study results about the role of fat in disease are sum-
marized in Box 4.3.

Box 4.3 FAT AND DISEASE: WHAT’S THE CONNECTION?

Total Fat and Heart Disease
Results from the large and long Women’s Health Initiative Dietary Modification Trial
(WHI DMT) showed that eating a low-fat diet for 8 years did not reduce the risk of
coronary heart disease events or stroke (Howard et al., 2006b), but critics argue that
it is very difficult to actually achieve a low-fat intake and that study participants may
not reduce fat intake enough to see positive results. Also, it may be that risk reduction
takes longer to observe than the 8-year-long WHI DMT.

Type of Fat and Heart Disease
Results from the Nurses’ Health Study show that replacing only 30 calories (7 g) of
carbohydrates every day with 30 calories (4 g) of trans fats nearly doubled the risk for
heart disease (Willett et al., 1993). Saturated fat also increased the risk but not as much.

Fat and Cancer
The role of total fat in promoting cancer is controversial. Results from the WHI DMT
showed that although a low–total fat diet did not prevent cancer, it did not rule out a
potential modest benefit against breast cancer (Prentice et al., 2006). Evidence that
certain types of fat promote cancer is suggestive, not conclusive, and the impact of
total fat is questionable.

Fat and Weight
Additional results from the WHI DMT show that women assigned to a low-fat diet did
not lose, or gain, any more weight than women eating a “usual” diet (Howard et al.,
2006a). In theory, cutting fat can cut calories and therefore promote weight loss; in
practice, low-fat diets are no more effective in promoting weight loss than are high-fat,
low-carbohydrate diets. The key to managing weight is total calories, not the propor-
tion of calories from carbohydrates, protein, or fat.