The first US dietary recommendations were set by the National Academy of Sciences in 1941. The recommended dietary allowances (RDA) were first established out of concern that America’s overseas World War II troops were not consuming enough daily nutrients to maintain good health. The first Food and Nutrition Board was created in 1941, and in the same year set recommendations for the adequate intakes of caloric energy and eight essential nutrients. These were disseminated to officials responsible for food relief for armed forces and civilians supporting the war effort. Since 1980, the dietary guidelines have been reevaluated and updated every five years by the advisory committees of the US Department of Agriculture (USDA) and the US Department of Health and Human Services (HHS). The guidelines are continually revised to keep up with new scientific evidence-based conclusions on the importance of nutritional adequacy and physical activity to overall health.

While dietary recommendations set prior to 1980 focused only on preventing nutrient inadequacy, the current dietary guidelines have the additional goals of promoting health, reducing chronic disease, and decreasing the prevalence of overweight and obesity.

Establishing Human Nutrient Requirements for Worldwide Application

The Department of Nutrition for Health and Development, in collaboration with FAO, continually reviews new research and information from around the world on human nutrient requirements and recommended nutrient intakes. This is a vast and never-ending task, given the large number of essential human nutrients. These nutrients include protein, energy, carbohydrates, fats and lipids, a range of vitamins, and a host of minerals and trace elements.

Many countries rely on WHO and FAO to establish and disseminate this information, which they adopt as part of their national dietary allowances. Others use it as a base for their standards. The establishment of human nutrient requirements is the common foundation for all countries to develop food-based dietary guidelines for their populations.

Establishing requirements means that the public health and clinical significance of intake levels – both deficiency and excess – and associated disease patterns for each nutrient, need to be thoroughly reviewed for all age groups. Every ten to fifteen years, enough research is completed and new evidence accumulated to warrant WHO and FAO undertaking a revision of at least the major nutrient requirements and recommended intakes.
http://www.who.int/nutrition/topics/nutrecomm/en/

Why Are Guidelines Needed?

Instituting nation-wide standard policies provides consistency across organizations and allows health-care workers, nutrition educators, school boards, and eldercare facilities to improve nutrition and subsequently the health of their respective populations. At the same time, the goal of the Dietary Guidelines is to provide informative guidelines that will help any interested person in obtaining optimal nutritional balance and health. The seventh edition of the Dietary Guidelines was released in 2010 and focused mainly on combating the obesity epidemic. USDA secretary Tom Vilsack says, “The bottom line is that most Americans need to trim their waistlines to reduce the risk of developing diet-related chronic disease. Improving our eating habits is not only good for every individual and family, but also for our country.” The 2015 Dietary Guidelines focus on eating patterns, which may be predictive of overall health status and disease risk. The Dietary Guidelines were formulated by the Food and Nutrition Board of the Institute of Medicine (IOM), which has recently changed their name to the National Academy of Medicine (NAM). These guidelines are from the review of thousands of scientific journal articles by a consensus panel consisting of more than two thousand nutrition experts with the overall mission of improving the health of the nation^[1].

Major Themes of the 2015 Dietary Guidelines

Consume a healthy eating pattern that accounts for all foods and beverages within an appropriate calorie level. A healthy eating pattern includes^[2]:

• A variety of vegetables from all of the subgroups—dark green, red and orange, legumes (beans and peas), starchy, and other
• Fruits, especially whole fruits
• Grains, at least half of which are whole grains
• Fat-free or low-fat dairy, including milk, yogurt, cheese, and/or fortified soy beverages
• A variety of protein foods, including seafood, lean meats and poultry, eggs, legumes (beans and peas), and nuts, seeds, and soy products
  Oils

A healthy eating pattern limits:

• Saturated fats and trans fats, added sugars, and sodium
• Cholesterol, in order to limit saturated fats.

Previously, the recommendation for cholesterol was less than 300 mg/day of cholesterol for the general public, and less than 200 mg/day for those with cardiovascular disease risk. The 2015 Dietary Guidelines recommends consuming as little dietary cholesterol as possible rather than quantifying it because someone consuming a diet according to the recommendations would consume around 100-300 mg daily and because dietary cholesterol does not impact blood cholesterol levels as much as previously believed^[3]. The reason for consuming as little cholesterol as possible is because many (but not all) foods that have cholesterol also have saturated fat.

Key Recommendations that are quantitative are provided for several components of the diet that should be limited. These components are of particular public health concern in the United States, and the specified limits can help individuals achieve healthy eating patterns within calorie limits:

• Consume less than 10 percent of calories per day from added sugars
• Consume less than 10 percent of calories per day from saturated fats
• Consume less than 2,300 milligrams (mg) per day of sodium

If alcohol is consumed, it should be consumed in moderation—up to one drink per day for women and up to two drinks per day for men—and only by adults of legal drinking age^[4].

High consumptions of certain foods, such as those high in saturated or trans fat, sodium, added sugars, and refined grains may contribute to the increased incidence of chronic disease. Additionally, excessive consumption of these foods replaces the intake of more nutrient-dense foods.

The average person consumes 3,400 milligrams of sodium per day, mostly in the form of table salt. The Dietary Guidelines recommend that Americans reduce their daily sodium intake to less than 2,300 milligrams. If you are over the age of fifty-one, are African American, or have cardiovascular risk factors, such as high blood pressure or diabetes, sodium intake should be reduced even further to 1,500 milligrams. The Dietary Guidelines also recommend that less than 10 percent of calories come from saturated fat, and that fat calories should be obtained by eating foods high in unsaturated fatty acids. The Dietary Guidelines stress the importance of limiting the consumption of foods with refined grains and added sugars, and introduce the new term, SoFAS, which is an acronym for solid fats and added sugars, both of which should be consumed in moderation in a healthy diet^[5].

Foods and Nutrients to Increase

The typical American diet lacks sufficient amounts of vegetables, fruits, whole grains, and high-calcium foods, causing concern for deficiencies in certain nutrients important for maintaining health. The Dietary Guidelines provide the following suggestions on food choices to achieve a healthier diet:

Source: Food Groups. US Department of Agriculture. http://www.choosemyplate.gov/food-groups/. Updated April 19, 2017. Accessed November 22, 2017.