The Evolution of the American Diet

How has the evolution of the American diet changed over the years? Looking back over the decades, the typical American diet has changed. A significant contributor to this change is the availability of certain foods. Many foods we have now were not available when our parents were growing up, and even less when we talked about our grandparents. 

The main thing that shaped their diet wasn’t food choices but what was available. But in current times, we grew up with an unlimited amount of options, so the main factor that shapes our diet is our choices; availability is now in second place.

How has the Evolution of the American Diet changed over the decades?

It’s safe to say that what we know about food is drastically more than we did 10 or 20 years ago. The major contributor to this change is the food supply chain and its availability. As more types of food became available more research on food followed, specifically the breakdown of food and how it affects energy production and the way it affects the body. Over time we learned what foods promote fat production, and muscle growth, and their correlation with chronic disease

1940s

In the 1940s, the Second World War was ongoing, and food rationing was introduced. Meat, cheese, butter, cooking fats, and sugar were heavily restricted, but potatoes, root vegetables, and bread were freely available. People ate a diet much higher in carbohydrates and lower in fats than we do today.

1950s

In the 1950s, people ate what was in season – no strawberries, fresh peas, or salad in winter. No one would dream of having their main meal of the day without a cooked dessert like tapioca or sponge and custard. In 1954 there was rejoicing because wartime rationing finally ended.

After rationing ended, people rushed to buy butter, sugar, and white bread. Bananas and oranges, which had virtually disappeared, began to return to shops. Shopping for food was much more expensive than today; food shopping took up one-third of the average income, compared to around 16% today.

1960s

The National Food Survey, conducted since 1950, shows our consumption of the fruit has slowly risen since the 1950s, but the consumption of bread, cereals, potatoes, and other vegetables has steadily fallen. 

The 1960s were a decade of change. As people began to take overseas holidays, dishes like Spaghetti Bolognese began to find their way into the diet. There was a growth in Indian and Chinese food. Overall there was an increase in the cultural diversification of food. 

The consumption of meat and sugar reached record levels. The sliced white loaf arrived, as did sugar-coated breakfast cereals. Tomatoes became available in winter for the first time. Frozen foods became a common sight in the shops.

1970s

The 1970s marked the start of a reduction in our intake of vegetables. The average person ate a pound of red meat each week, compared to just over half of that today. Fruit juice arrived in the shops. The sliced white loaf became even more popular in its new plastic wrapper (previously, all bread had been sold on waxed paper). Frozen food continued its onward march, and ready meals became popular. 

Supermarkets began their dominance in the food industry. This was also the last decade in which children could depend on a guaranteed hot meal in school.

1980s

In the 1980s, the increasing number of working women helped to change the face of food. Out went meat, potato, and two vegs; in came the microwave and meals based on pasta. This was also the decade in which takeaway hamburgers began to eat their way into our culture.

More people were living independently, further fuelling the market for fast food. Milk was no longer something you always found in glass bottles. Now it started to come in waxed cardboard or plastic cartons. The idea of low fat was pushed.

 

1990s

In the 1990s, the big supermarkets completed their dominance of the food industry. The range of products became massive, including previously unknown salad leaves and exotic fruit and vegetables. The move towards faster food continued.

In 1980, the average meal took one hour to prepare. By 1999, that had dropped to 20 minutes. Breakfast became a casualty of our speeded-up lifestyle. Cereal bars were introduced, but many contained a high level of sugar. The ‘Got Milk?’ became advertised; there supposedly was an oversupply. 

2000s

In the 2000s, the trends of the previous decades accelerated. National cuisines, such as Thai, became more popular thanks to the efforts of supermarkets to bring us something new regularly. Snacking continued to rise, while fruit and vegetable intake declined. However, the population soon began to become more aware of increasing obesity rates and unhealthy lifestyles thanks to documentaries such as ‘Supersize Me,’ which focused on the impact of living on McDonald’s meals.

Soon, foods high in fat and sugar, such as Turkey, Twizzlers, chips, and donuts, disappeared from school cafeterias across the country, and McDonald’s added salads to its menus.

2010s

In the 2010s, the rise of the smartphone had a considerable impact on our social lives and our eating and health habits. Fast food delivery became available at our fingertips, while online streaming services made spending hours on the sofa binging on your favorite TV shows the norm. Meanwhile, plant-based diets increased in popularity due to climate change and sustainability concerns.

‘Clean eating’ movements sprouted amongst fitness and health-conscious communities of influencers online, sparking a rise in the popularity of protein powders, weight loss teas, and juice cleanses. More exotic and trendy ‘super foods’ became household staples across the country, such as avocadoes.

2020s

And as the 2020s unravel before us, the trend towards moving less, sitting more, and unhealthy eating habits only seems to be on the rise. With the COVID-19 pandemic and lockdowns closing bars and restaurants, ordering fast food or cooking lavishly at home became one of the few remaining pleasures available for many people to enjoy. This and paired with the closure of gyms and the rise of working from home, much of the population has become more sedentary than ever before. It is estimated that the average person has gained about 10-20 lbs during the pandemic.

How the Evolution of the American diet affected the majority of what people consume

The NHANES is an ongoing national study that surveys participating Americans about their diets. According to the 2017-2018 NHANES data, the average American adult eats 

2100 calories a day, 

• 16% of those calories from protein, 
• 47% of carbohydrate 
• 36% from fat. 
• 22% of all calories from added sugars

Current Dietary Guidelines for Americans

1. Follow a healthy dietary pattern at every life stage.
2. Customize and enjoy nutrient-dense food and beverage choices to reflect personal preferences, cultural traditions, and budgetary considerations.
3. Focus on meeting food group needs with nutrient-dense foods and beverages, and stay within calorie limits.
4. Limit foods and beverages higher in added sugars, saturated fat, and sodium, and limit alcoholic beverages.

The DGA sets the ideals for what healthy eating is and then compares those ideals to the Standard American Diet. 

The DGA says Americans should eat fresh fruits and vegetables, whole grains, lean protein, and healthy oils for good health. 

When the SAD is compared to this ideal, the DGA says we eat too much saturated fat in the form of red meat and high-fat dairy products, too much fast food, and too many refined carbohydrates, added sugars, salt, and overall calories.  

These less-than-ideal choices, they report, are why so many Americans suffer from the chronic diseases of obesity, heart disease, diabetes, and cancer.

For instance, relying on fast food for most meals does increase calorie, salt, and sugar intake substantially while reducing vitamin and mineral intakes needed for good health. This is especially true for younger Americans. 

However, the research shows that only about 37% of adults eat fast food regularly. As shown by the USDA Healthy Eating Index, a measure of diet quality, American adults make “healthy” food choices about 60-65% of the time.

• That means for a majority of meals, Americans follow the Dietary Guidelines. Yet, the problem of chronic diseases in the US continues to worsen.

What does the DGA get wrong?

The Nutrition Coalition, a respected group of dietary professionals, identifies the answer for the increase of chronic disease in America as rooted in the DGA’s recommendation to eat less fat and more carbohydrates. 

They recommend that a low-carbohydrate diet would be healthier for the American population, especially when considering that 60 percent of Americans already suffer from metabolic disorders. Metabolic disorders refer to disruptions in the normal processes of breaking down food into its nutrient parts–fat, protein, sugar, vitamins, and minerals. High intake of carbohydrates is a primary factor for many of these disorders.

Interestingly, recent research on the safety and health effects of low-carbohydrate diets strongly supports this conclusion. 

Inflammation

Inflammation is a condition in which a person’s immune system has been triggered to fight some irritation or damage taking place within their body. 

For example, the immune system response is what causes pain and redness around the area of a splinter in one’s finger.  If the offending cause is not removed, the immune system response and the associated inflammation can eventually become a chronic condition that causes further damage. 

Chronic inflammation is implicated in various diseases, including heart disease, metabolic syndrome, diabetes, cancer, autoimmune conditions such as rheumatoid arthritis and infertility, and mental disorders such as depression.

• One of the main triggers for chronic inflammation in the body is rampant glycation. This is a process where the sugar molecules in the bloodstream stick to our cells and tissues.
• A small amount of glycation is normal and can easily be repaired by the body. But when a person’s daily diet includes large amounts of carbohydrates, blood sugars become chronically high, glycation rates increase, and a chain reaction of damage is set off that results in increased inflammation. 

Research shows that refined carbs may cause inflammation in your body. “It’s similar to added sugars because nothing slows their breakdown. They hit your bloodstream quickly and spike your blood sugar. And elevated blood sugar creates an inflammatory response.

Heart Disease

The carb-fueled inflammatory process is one of the main factors linking the standard American diet to cardiovascular disease. 

Cardiovascular disease is typically associated with damage to the body’s vascular system. This system of blood vessels brings oxygenated blood from the lungs to the heart and other body systems. 

• Consuming lots of refined carbohydrates sets up a domino effect in which glycation and inflammation injure the linings of the blood vessels supplying the heart.
• As inflammation sets into those injured areas, a loss of vessel suppleness leads to high blood pressure. Further injury leads to atherosclerosis (the infamous “hardening of the arteries”) and vascular blockages, which can trigger a heart attack and stroke.

Diabetes

The high-carb intake of The Standard American Diet contributes to diabetes by spiking insulin levels and increasing Inflammation. Diabetes is one of the most damaging diseases of civilization. People with diabetes can no longer manage the amount of sugar in the bloodstream. 

In 2018, the Centers for Disease Control (CDC) reported that more than 34 million Americans had diabetes. Type 2 diabetes is the most common and strongly linked to refined and total carbohydrate consumption. Both are staples of the Standard American Diet. 

The human body is not designed to handle consistently high amounts of sugar. Eating carbs for three meals a day with snacks in between floods the bloodstream with toxic glucose levels. This constant stream of glucose stresses the adrenal glands and stimulates your pancreas to produce the hormone insulin in excessive amounts. 

Over time, increased levels of blood sugar and insulin result in high levels of glycation and inflammation, which trigger more widespread damage, including: 

• loss of eyesight 
• kidney failure 
• nerve damage
• heart disease
• serious infections

Cancer

The high carb intake of the standard American diet is also a factor in cancer development.  Many cancer cells rely on high blood sugar to flourish and grow. Consuming large amounts of carbohydrates provides the fuel they need.   

• Inflammation is also a factor in tumor development and cancer metastasis. 

In short, eating a SAD diet high in refined carbohydrates sets up conditions in the body that encourage the establishment and growth of cancer.

An important point to note here is that the USDA Dietary Guidelines advise that red meat consumption should be limited because it is linked to cancer in many epidemiological studies.  

• However, a meta-analysis of the research on the relationship between red meat consumption to cancer mortality was published in 2019 and concluded that the “possible effects of red and processed meat consumption on cancer mortality and incidence are very small, and the certainty of the evidence is low to very low.” 
  • https://pubmed.ncbi.nlm.nih.gov/31569214/
  • Of 118 articles (56 cohorts) with more than 6 million participants, 73 articles were eligible for the dose-response meta-analyses, 30 addressed cancer mortality, and 80 reported cancer incidence. Low-certainty evidence suggested that an intake reduction of 3 servings of unprocessed meat per week was associated with a very small reduction in overall cancer mortality over a lifetime.

Inflammatory Bowel Diseases

The carbohydrate-rich standard American diet is also strongly linked to inflammation within the intestinal system. 

Case rates of chronic inflammatory bowel diseases have increased significantly since 2015, with over a million people in the United States suffering from either Crohn’s disease or ulcerative colitis. 

Gut Microbiota

The intestinal tract is home to billions of gut bacteria collectively termed the gut microbiota.

This ecosystem of organisms helps us digest our food while protecting against foreign toxins. It’s also responsible for producing essential vitamins and neurotransmitters.

Recent research indicates that healthy gut microbiota is critically important not only to a properly functioning digestive system but for our overall mental, metabolic, and nervous system health. 

The Standard American Diet afflicts the gut when sugar, fiber, and plant toxins damage cells lining the intestinal tract. The immune system responds to the damage with an inflammatory response that destroys gut bacteria. This allows the infiltration of toxic organisms, which encourages further inflammation.

• Wheat gluten and other cereal grains and flours are major offenders in gut cell damage and inflammatory bowel conditions. Several studies report that foods high in fermentable carbohydrates (FODMAPS) worsen irritable bowel conditions. 

Although red meat consumption is often cited as a factor in bowel diseases, little controlled research data exists to support this hypothesis. 

• One of the recommendations for ulcerative colitis and Crohn’s disease is a low-carb diet and a very low-carb diet.

Infertility

Another body system sensitive to the high carbs and plant toxins in the Standard American Diet is the reproductive system. 

• Research confirms that high blood sugar can increase the amount of glycation and oxidative stress within the reproductive organs. This reduces ovarian function and dysfunction in the granulosa cells, which protect egg development. 
• High levels of glycation also reduce the activity of female steroid production and follicular development in the ovaries. And finally, glycation and oxidative stress also cause damage to the capability of male testicles to produce normal sperm cells.

Imbalance of omega-6 over omega-3 in the Standard American Diet

The standard American diet also causes an imbalance of essential fatty acids. You’ve probably heard the term omega-3 and omega-6 fatty acids during commercials for fish oil supplements.  But what are these substances, and why are they important in our diet?

Unsaturated Fats

Omega-3 and omega-6 essential fatty acids (EFA) are “essential” because they cannot be synthesized by the body and must be derived from dietary sources. They are also polyunsaturated, a term that refers to the types of chemical bonds within the molecules. 

Saturated Fats

Fats like butter and coconut oil have stable chemical bonds called “saturated” bonds, called saturated fats. Olive oil has one unstable bond and is a monounsaturated fatty acid or MUFA.  But omega-3 and omega-6 fatty acids have multiple unstable chemical bonds, so they fall into polyunsaturated fatty acids or PUFA.

We only need a small amount of PUFA each day, but they are vitally important as they play a role in nearly every metabolic function in the body. And each type of essential fatty acid has different effects on body systems, as shown in the graphic below.

Eicosanoids and Inflammation

Essential fatty acids are also sources for the body’s production of a class of hormone-like molecules called eicosanoids. 

These molecules are among the most potent regulators of cellular function, and they are produced by almost every cell in the body. Eicosanoids exert a wide-ranging and profound influence on your health. Among other important effects, they regulate blood pressure, lung function, and blood clotting mechanisms.

The type of eicosanoids that are dominant within the body depends on the types of essential fatty acids being consumed in the daily diet. Since omega-3 fatty acids have an anti-inflammatory effect on the body, eating more omega-3-rich foods results in an accumulation of anti-inflammatory eicosanoids. In contrast, eating more omega-6 fatty acids increases eicosanoids which have pro-inflammatory properties.

Decline in Omega-3s

In the last 100 years, the amount of omega-3 polyunsaturated fats in the Western diet has declined while the consumption of omega-6 fatty acids has increased substantially. This is due to the development and use of vegetable and seed oils in our food supply.

The USDA advises Americans that vegetable and seed oils (olive oil, soybean oil, canola oil, and sunflower oil) are healthy fats. Still, it needs to mention these oils are highly processed industrial products. 

• Almost all processed foods contain one or more vegetable oils.

The abundance of omega-6 oils in the standard American diet tilts it toward being pro-inflammatory, and not surprisingly, research links an imbalance of omega-3 to omega-6 fatty acids to a long list of chronic diseases, including heart disease, cancer, diabetes, and other metabolic diseases, pregnancy issues and mood disorders such as depression and bipolar disorder.

How the Standard American Diet Affects Mental Health

The body of research on the relationship between mental health and diet continues to grow, and it supports the hypothesis that not only is a deficiency of anti-inflammatory fatty acids such as EPA involved, but that oxidative stress can be a trigger for mental issues as well.

Many psychiatric disorders can be linked to issues with the optimal amounts of brain neurotransmitters such as serotonin and dopamine. Julia Ross, MA, is the author of a book called the Diet Cure, and she lays out the evidence for how blood sugar instability and fatty acid deficiencies can impair our brain chemistry. Other research points to the link between refined carbohydrate intake, gut health, and psychological disorders.

Take a peek and go through this on the show; pretty interesting https://stacker.com/food-drink/50-ways-food-has-changed-last-50-years 

https://www.doctorkiltz.com/standard-american-diet/ 

Learn about the evolution of the American Diet by clicking on the full video here 👇👇👇

TIME STAMPS:

00:00 Introduction
02:18 The evolution of our Diet
05:25 The availability of unhealthy foods
09:46 1940
10:20 1950
12:22 1960
13:20 1970
15:11 1980
16:36 1990
18:15 2000
19:08 2010
22:18 2020
27:25 What do the majority of people consume?
30:06 Current Dietary Guidelines for Americans
33:15 What does the DGA get wrong?
34:59 Inflammation
37:40 Heart Disease
38:00 Diabetes
41:54 Cancer
45:11 Inflammatory Bowel Diseases / Gut Microbiota
47:30 Infertility
50:39 Imbalance of omega-6 over omega-3
54:04 Eicosanoids and Inflammation
55:25 How the Standard American Diet Affects Mental Health
56:38 Wrapping up the show