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We constantly make certain assumptions about ‘processed’ versus ‘whole’ foods.

But are we really clear what these terms mean?

In this post, we examine exactly what the word ‘processed’ means and whether or not some processed foods can have a place in a healthful whole food plant-based lifestyle.

Food Processing… a Definition

The term processing includes chopping vegetables, blending fruits, boiling, frying, grilling, pickling, jarring, canning, freezing, pasteurizing, fermenting or adding preservatives, artificial sweeteners, salt, sugar or fat.

It can be as simple as freezing or drying food to preserve nutrients or as complex as creating a frozen meal with just the right balance of ingredients.

Many of us think of ‘processing’ as something that happens in big manufacturing factories. What we often forget is that ‘processing’ happens at home too.

For example, when we make nut milk we blend soaked nuts and water and are thus ‘processing’ food. When we remove water from a raw food in a dehydrator, we are once again processing it. (However in both examples, the processing is minimal and we can almost always identify the original whole food. I will explain why that is important a little later).

The Concept of Food Processing Is Nothing New

It is essential to underline the fact that food processing has existed for centuries. Since ancient times, humans have been developing ways to make foods taste better, last longer and transport easier.

For example, salting foods was developed as a way to preserve soldiers’ and sailors’ foods for long-term journeys. Sun drying, roasting, baking and smoking vegetables, fruits (and meats) extended the life of foods – preventing microbial growth and spoiling.

The 1800s ushered in a new era for food preservation techniques.

Nicholas Appert invented hermetic bottling to preserve foods for French troops in 1809. Peter Durand introduced canning one year later. Louis Pasteur added pasteurization to food processing in 1864, which destroys pathogens through heat and allows people to safely drink milk, juices, and beers.

In the 20th century, these techniques were taken to another level. To fulfill the unending appetite for convenience, freezing, concentrating, artificial sweeteners and chemical preservatives were all routinely added to foods. In the 1950s, pre-prepared bakery goods, frozen foods, and TV dinners splashed onto the scene and the processed foods craze took on a whole new dimension.

Are There Any Benefits to Processing?

While the word ‘processed’ has earned a negative reputation, it is important to stress that not all processing is ‘bad’.

Even though processing can often decrease a food’s nutritional value, some processing may keep or even increase it. For instance, almond milk, smoothies, and raw banana ‘ice cream’ are all ‘processed’ but are still brimming with nutritional value.

Food processing has many unsung benefits including the ability to:

  • Preserve Nutrients. Snap freezing fruits and vegetables after harvest can decrease the loss of nutrients that usually happens during storage. Canned beans are nutritionally equivalent to cooked beans, but are easier and quicker to use to prepare meals at home (just make sure to get the ‘no salt added’ varieties).
  • Help Nutrients Be Absorbed. Canning and cooking through steaming or boiling can make certain nutrients more easily absorbed by the body. For example, heat increases the bioavailability of beta-carotene in carrots and lycopene in tomatoes.
  • Make Foods Last Longer so they can withstand shipping over long distances. This helps alleviate food shortages and provides nutrition to areas of the world where healthful foods cannot be grown. In fact, the processing of food has allowed us to safely feed millions around the globe.
  • Increase Availability of High-Quality Foods. Food processing gives all of us access to a much more varied diet, as many seasonal (and regional) foods are now available year-round. Instead of having to farm and harvest all our food ourselves, we instead have access to a variety of fruits, vegetables, whole grains and legumes anytime of the year.
  • Remove Toxins and Prevent Food-Borne Illnesses. Processing can destroy pathogens and toxins and, therefore, help prevent food-borne illnesses.

But What About the Downside?

Having said all that, ‘processed’ foods have a bad reputation for a reason.

Here are some of the principal ones:

  • The Dangers of Food Additives. Food additives are substances added during food processing to preserve or enhance taste and appearance. Some food additives have been used for a long time such as vinegar in pickling. However, in the second half of the twentieth century, more additives (both natural and artificial) have been introduced to the food supply.  Natural additives include ‘acids’ (e.g. vinegar, citric acid, lactic acid) that make flavors ‘sharper’ and act as both preservative and antioxidant, and other antioxidants (e.g. vitamin C or ascorbic acid), which inhibit the effects of oxygen on food.  Artificial additives include, among others, many food coloring, flavors and flavor enhancers, and flour treatment agents.
  • The Risk of Contamination. Processing which requires the repeated use of manufacturing equipment introduces a potential risk of contamination if the equipment malfunctions or is not properly sanitized between uses.
  • The Reduction of Nutritional Density. And probably most important, food processing can change a food’s nutritional density. Heat destroys certain vitamins, including vitamin C, making some canned fruits and cooked vegetables less nutrient dense than the fresh foods.

There Are Different Degrees of Processing

So when it comes to food processing, how do we determine what is healthful versus what is not?

The secret to evaluating a processed food lies in the amount of ‘processing’.

Let’s, therefore, divide foods up into minimally, moderately and ultra-processed foods:

  • Minimally Processed Foods

A ‘minimally processed’ food requires little processing or production and normally contains no (or low amounts of) added sugars, oils or salts.

Frozen fruits and vegetables–processed in order to preserve their nutrients and freshness at their peak—are one example. Pickled vegetables are another.

Prepared commercially or at home, this category includes: washed and packaged fruits and vegetables, bagged salad, kale chips, pickles, canned tomatoes, and beans, roasted and ground nuts, roasted and ground coffee beans, rolled oats, and fresh nut butters.

  • Moderately Processed Foods

Those are foods whose raw ingredients have been transformed into something new (i.e. flour into a cookie, milk into yogurt). If chosen wisely, many can be healthful as long as their added sodium and sugar content is low and they contain no added oils.

Moderately processed foods tend to me more calorie dense than nutrient dense.

Examples include instant potato mix, jarred spaghetti sauces, cake mixes, dressings, breakfast cereal, jams and jellies, dairy-free cheeses and yogurts, and granola bars.

  • Ultra-Processed Foods

Ultra-processed foods are the hyper-palatable, ready-to-consume, usually refined food products that are calorie-dense and nutrient deficient, containing high amounts of fat, sugar and salt. (Pop Tarts anyone?)

Some of the classics include cookies, potato chips and other chips, soft drinks, and frozen desserts like ice cream. It also includes many types of bread and grain-based desserts.

Do Processed Foods Belong in a Whole Food Plant-Based Diet?

All foods lie on a continuum from completely unprocessed (i.e. foods we eat exactly as they exist in nature) to completely processed (i.e. a Twinkie or Doritos).

Logically, the more you eat foods on the ultra-processed side of the spectrum, the less healthful your diet will be.

Therefore, the recommendation is to eat as many fresh ‘straight from nature’ foods and as few moderately or ultra-processed foods as possible.  Even better if moderately processed foods are substantially reduced and ultra-processed foods are completely avoided.

Having said that, there are certain minimally and moderately processed foods that can be successfully (and healthfully!) integrated into a whole food plant-based diet. A few examples are: no salt added canned beans, frozen vegetables and fruits, SOS-free packaged nuts and nut butters, SOS-free hummus, and SOS-free marinara sauce and salsa.

Whole vs. Processed—Looking at the Numbers

Finally, the same way ‘processed’ does not necessarily mean it is harmful, ‘whole’ does not necessarily mean it is always healthful or it can be eaten in any amount.

What matters most is the numbers – i.e. how many calories, and how much sodium, sugar, and fat is found in a food. Also important is their concentration levels.

To illustrate this point, let’s use the example of sugar.

Sugars naturally occurring in fruits, vegetables, tubers and roots, and whole grains are ‘mixed’ with water and fiber and packed with nutrients. But dried fruits like raisins or dates have a much greater sugar concentration because a lot of the water was left out. Even though they are considered ‘whole’, ‘natural’, ‘unprocessed’ sugars, their (sugar) density is high.

Below is a comparison of sugar concentration or density (grams of sugar per lb. of food) for different ‘whole’ plant foods:

  • Peas – 21
  • Corn – 28
  • Orange – 42
  • Apple – 47
  • Raisins – 268
  • Dates – 301
  • Table Sugar – 453

As you can see, the ‘whole’ raisins and dates have sugar concentrations a lot closer to table sugar itself whereas other ‘whole’ plant foods (like peas or corn) have far lower sugar concentrations.

The best approach to balancing sugar (or fat) concentrations is to combine foods high in sugar (or fat) with foods that are in the lower density range. So you can add a bit of brown sugar or dates to a bowl of oatmeal and the oatmeal will ‘dilute out’ the highly concentrated sugar.

The same logic goes for fat. You can add a sprinkle of nuts or seeds to a green salad, and the high-fat concentration in those nuts and seeds will be ‘diluted’.

For the healthiest dietary choices, carefully watch the sugar and fat densities in any food you eat—even if it is a ‘whole’ food.

When it comes to ‘whole versus processed’, your best bet is to stick to food choices at the unprocessed or minimally processed end of the food spectrum, always selecting the ones with little or no added fat, sugar, and sodium.

Rosane Oliveira, DVM, PhD

President & CEO, Plant-Based Life Foundation | Dr. Rosane Oliveira combines a lifelong passion for nutrition with 25 years of genetics research to create programs that help people develop healthy habits on their journey towards a more plant-based lifestyle. She is a Visiting Clinical Professor in Public Health Sciences and was the founding director of the first Integrative Medicine program at the UC Davis School of Medicine. She completed her postgraduate studies in Brazil and did her postdoctoral training in immunogenetics and functional genomics at the University of Illinois at Urbana-Champaign.