USANA Nutritionals

2008/2/13

Glitches in the Glycemic Index

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@ 10:47 AM (4 months, 22 days ago)
Imagine a categorizing system in which numbers are assigned to foods, allowing you to choose the foods that curb appetite, help shed excess pounds, lower your risk for diabetes, and improve heart health. These in fact are the claims of popular diets that use the Glycemic Index—GI diet, for short. 
 
The Glycemic Index ranks carbohydrate-containing foods (on a scale from 0 to 100) based on their effects on blood sugar levels in the body. Eating highly processed foods, such as bread made from refined white flour, raises blood sugar higher and faster than does eating whole foods, such as whole-wheat bread or an apple. Foods—like white bread—that cause the most rapid rise in blood sugar are given a higher number, while whole-wheat breads and apples have lower ratings. A rating of 55 or below is considered low, and 70 or above is considered high. 
 
Additional information and values for the GI diet can be found at: www.GlycemicIndex.com, and www.Mendosa.comThe Glycemic Indexes of a few foods are listed here:  
 
Food Item
GI
Peanuts
14
Grapefruit
25
Pizza
30
Oranges
48
Potato Chips
54
Snickers Bar
55
White Rice
64
White Bread
70
Popcorn
72
Baked Potato
85
 
 
The Premise
Proponents of the GI diet believe that the lower the GI number of a carbohydrate food, the better.   High GI foods are digested and metabolized more quickly, causing a rapid rise in blood glucose levels. This creates a dramatic spike in levels of the hormone insulin, which works to remove sugar from the blood. These responses can lead to an overproduction of insulin, contributing to weight gain. Therefore, carbohydrate foods with low Glycemic Indexes cause less insulin secretion and slow the clearing of glucose from the blood stream—resulting in greater satiety, and fewer calories consumed throughout the day. 
 
The Spark Response
Using the Glycemic Index for meal planning is a very complicated process. Here are some of the limitations:
 
  • Only about 5% foods in the national food database have been tested.
  • There is usually a wide variation in the GI measurement. A potato can be as low as 56 or as high as 100. In fact, a food’s GI score can change based on the food’s ripeness level. 
  • A food’s GI score can also change based on preparation techniques. Grinding and cooking can elevate the GI score of some foods, because they become quicker and easier to digest.
  • GI testing is done on individual foods, but we consume most foods in combinations. Fiber, protein, and fat will usually reduce the Glycemic Index of a meal.
  • The rate at which different people digest carbohydrates varies. And each person’s glycemic response may vary throughout the day.
  • When certain high glycemic foods are eliminated from the diet, so are vital vitamins, minerals, fiber, and phytochemicals. Watermelon has a GI of 72 but it is high in potassium, vitamin A, and lycopene, for example.
  • Relying on the Glycemic Index can still lead to overeating and weight gain. Peanuts look like the perfect choice with a GI of 14, but with about 400 calories in ½ cup, they won’t help shed pounds when eaten in excess.
The Glycemic Index is a marvelous tool for ranking carbohydrates. However, it is currently only in its infancy regarding health benefits. More research is necessary to make it a truly valid, reliable, and applicable teaching tool. The simple facts still remain:

  • 20% of Americans’ calories come from high carbohydrate foods, such as cakes, cookies, pies, pastries, ice cream, sugar, candy, soda pop, and chips. 
  • Fresh fruits and vegetables, and whole grain products (whole-wheat breads and pastas, brown rice, and wheat germ) are nutritionally superior to highly processed, refined products.
  • Simply limiting the total number of carbohydrates you consume at a meal can more easily control your blood sugar levels.
  • You probably don’t need a complicated rating system to confuse you about which carbohydrates to include in your diet.

 

USANA Nutrition

2008/2/12

THE "AVERAGE DIET" THEORY

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@ 10:08 AM (4 months, 23 days ago)

THE "AVERAGE DIET" THEORY

It would be nice to offer a solution to the problem of good nutrition by drawing up diets that would be right for everyone. Unfortunately, this is not as easy as it sounds, for several reasons.

First, foods mat are commonly found in one area of the country or in the diet of one ethnic or economic group may be uncommon in another. People's eating habits also vary widely, even within ethnic groups and regions of the country.

Second, a diet evaluation must include only food that is actually eaten. If considerations are based only on what is bought or prepared, the resulting nutritional picture will be distorted.

Third, the way you prepare and cook raw and processed foods at home may affect their vitamin content. For example, paring certain vegetables before cooking often results in the loss of most of their water-soluble vitamins. Baking and other cooking methods can also lead to vitamin loss.

When estimating the vitamin losses from your food during preparation, remember that it is unreasonable to expect that the preparation conditions of test foods will be identical to those being prepared in your home. Therefore, individual diets can be evaluated only by analyzing the final food product.

Fourth, your dietary or body level of one vitamin or mineral may influence your requirement for another. For example, many of the water-soluble vitamins' functions are interrelated because they all participate in the series of chemical reactions known as the Krebs cycle, which is involved in energy generation. Thus, a deficiency in one vitamin may affect the ability of the other vitamins to function. The nutrients that are interrelated in this way are niacin, thiamin, pyridoxine, riboflavin, biotin, pantothenic acid, choline, and cyanocobalamin.

Vitamin needs can also be related to the nature of your dietary intake. More thiamin, niacin, riboflavin, and other water-soluble vitamin requirements are needed in a high-carbohydrate diet. In contrast, a high-protein diet calls for increased pyridoxine and has an effect on the amount of riboflavin the body stores. Zinc seems to play a role in the action of vitamin A, so that vitamin A deficiencies can be more easily corrected if there is a sufficient amount of zinc in the diet And vitamin C (ascorbic acid) is a factor in the efficient absorption of iron from the gastrointestinal tract. Thus it is possible that you are taking enough iron but don't have enough ascorbic acid in the diet to get the full value of that iron. Usually, however, the situation is reversed, with more than enough C and too little iron in the diet.

Fifth, it is difficult and time consuming to translate information from nutrition value tables to our daily diet. For example, to determine the vitamin content of a simple ham sandwich on white bread, we must find the listing for "Ham: piece, approx. 4 1/8 in. long, 2 1/4 in. wide, 1/4 in. thick; wt 1 1/2 oz." Assuming that three such slices are used in our sandwich, we can determine that, from the ham alone, we will gain no vitamin A, 7.2 mg of niacin, 0.37 mg of riboflavin, 0.81 mg of thiamin, and no vita¬min C. Similar steps must be followed for every part of the sandwich, and then for total food intake.

Interestingly, the technology explosion has led to the introduction of a number of programs and services that will analyze your diet for vitamin and mineral content—as well as for fat, cholesterol, sodium, and other nutritive components—using a computerized listing of the information contained in the United Stales Department of Agriculture (USDA) tables on the nutritive value of American foods.

These computer programs can help you find an optimal diet by pointing out where your diet is lacking and making suggestions as to how to improve your eating patterns.

THE DIETARY GUIDELINES FOR AMERICANS

Over the years, nutrition and food researchers have developed a set of standard recommendations for the kinds of foods we should eat to maintain a healthy nutritional state.The Dietary Guidelines for Americans are the official policy of the United States Department of Agriculture and are updated every five years. The guidelines describe food choices that will help you meet the RDA/DRIs. They also intersect with the nutrition labeling that now appears on all packaged food products.

Here are the basic recommendations contained in the latest edition of the Dietary Guidelines for Americans:

Eat a variety of foods. No one food can supply all of the vitamins, minerals, and other nutrients your body needs. By varying the foods you eat, you have the greatest chance of obtaining the full range of nutrients. The Food Guide Pyramid offers information on the number of servings and amounts of various foods that are most healthful to consume.

Balance the food you eat with physical activity and maintain or improve your weight. Being overweight dramatically increases the risk for many diseases, such as high blood pressure, heart disease, stroke, diabetes, cancer, arthritis, and breathing disorders. Since many adults have a tendency to gain weight with age, this guideline encourages weight maintanance or loss as a goal of good health.

Choose a diet with plenty of grain products, vegetables, and fruits. These foods are the basis of a varied and healthy diet. They contain vitamins, minerals, complex carbohydrates, and other compounds that are healthful, and they are usually low in fat.

Choose a diet low in fat, saturated fat, and cholesterol. Although some dietary fat is needed to ensure good health, most Americans consume way too much fat and cholesterol. Such high-fat diets raise the risk of obesity, heart disease, and cancer.
 
Choose a diet moderate in sugars. As with fat, Americans tend to go overboard with sugar, which is high in calories.

Choose a diet moderate in sodium. Sodium has been associaed with high blood pressure. Sodium and sodium chloride (salt) are found in large amounts in processed and prepared foods.

If you drink alcoholic beverages, do so in moderation. Alcohol is high in calories and typically devoid of nutrients and can cause a number of illnesses if consumed to excess. Moderation is defined as no more than one drink per day for women and two drinks a day for men.

USANA Nutrition