Let’s talk about salads. We love to eat them, particularly in the spring and summer months because they’re so cool and crunchy and fresh. We also know that we need to eat more vegetables in general because of their high nutrient content. What better way to “beef” up our vegetable intake than by eating a great big salad every day?
Well, there are a couple of problems with that. Firstly, and most seriously, there is the increasing frequency of E coli outbreaks in fresh produce. If you go back a couple of decades, most people were more worried about E coli outbreaks in their meat and poultry products. Back then, improperly cooked hamburger or chicken were the most common culprits – so much so that a vegetarian diet began to seem, not only the healthier choice, but the safer one as well.
Jumping back to current times, however, and the situation has changed considerably. According to a 2015 estimate from the CDC, produce is now the most common cause of food-borne illnesses, comprising 42% of all cases, while meat and poultry are the culprits only 22% of the time. Vegetable row crops, such as lettuce, broccoli, celery, asparagus are most commonly implicated. A fifth of all outbreaks are caused by lettuce alone.
Which brings us to the most recent E coli outbreak – one that some are calling the worst since 2006, at least when it comes to leafy greens. It has sickened 98 people and hospitalized 46, including 10 who developed kidney failure. You may have heard of it. The suspected cause was a crop of romaine lettuce grown in Yuma, Arizona. Ironically, our newfound preference for fresh, pre-made salads, made with every intention of improving our health, is instead increasing our risk of severe illness and death.
Pathogens in chopped and pre-packaged lettuce are thought to be rinsed off with the use of a special chlorine wash, but studies show that these rinses are only partly effective at removing bacterial contamination. The reality is that vegetables are grown in dirt, irrigated with water that may be contaminated with cow manure, and then handled by many other people and machinery all along its way to your grocery store. Bacterial contamination can occur anywhere along this path. The only sure way to kill pathogens is to use heat, and we prefer to eat our lettuce raw.
This brings us to the second problem with eating salads on a regular basis: much of the nutrient content of vegetables is lost when they are eaten raw. Many nutritionists and natural health practitioners will insist that vegetables are best eaten raw because of their high enzyme content, which assists with their digestion and assimilation. Since cooking will kill off these naturally occurring enzymes, it is thought best to avoid the heat and eat them raw.
However, while cooking does remove some beneficial enzymes, it also breaks down the cellulose matrix (plant fibre) so that nutrients are more available to your body. You can see this when vegetables are lightly steamed. The colour of the vegetables becomes brighter, richer. This is a sign that the vitamins and minerals in the vegetables have been released, and are now more available to your body. In Chinese medicine, there is a saying: “It’s not what you eat, it’s what you assimilate”. If your body cannot easily extract the nutrients from raw vegetables, then there is no benefit in eating them.
According to Chinese medicine, raw vegetables are also thought to be very cooling, and weakening to your digestive system. This makes sense. If your digestive organs have to expend a lot of energy in order to extract the nutrients from raw vegetables, there is a high gross output for little net gain. When vegetables are steamed or lightly cooked first, part of the digestive process has already been accomplished for them. The nutrients in the vegetables are now more readily available to your body, resulting in a lower gross output and a higher net gain.
Bottom line: your digestive organs are less stressed when eating cooked vegetables when compared with raw, and yet still receive a greater reward of nutrients for this reduced effort. It all translates into stronger, sturdier organs that will retain their vitality well into your years. And since raw vegetables are now more dangerous to consume because of potential bacterial contamination, this is all the more reason to steam your salad before you eat it.
About the author: Rebecca Wong has an honours degree in English Literature from the University of Waterloo, and has been working in the herbal business since 2000. She has received her training in acupuncture and herbalism from respected authorities Paul Des Rosiers and Vu Le at the Ontario College of Traditional Chinese Medicine in Toronto, and Michael Tierra at the East West Herb School in California.