Are Raw Vegetables Healthier Than Cooked Vegetables?
The Raw Diet
Boy, there some serious claims out there about the health benefits of an all-raw diet. The proponents of a raw diet basically state that cooking denatures or destroys essential enzymes in the food, that all food has a kind of “life force” that is killed off by cooking. Supposedly, the enzymes in foods are necessary for proper digestion and that by destroying them in cooking, we’re making it very difficult for proper digestion to occur. Of course, I’d counter that claim with the question, “if foods are made to digest themselves, why do we have such complicated digestive machinery?”
Unfortunately for proponents of this “life force,” there is absolutely no way to verify that this exists. Of course, there’s also no way to disprove it, so it comes down to essentially a religious faith in the “life force” of your vegetation. Now with enzymes, it is supposed that cooking food kills off the enzymes and forces the body to use some of its own finite “enzyme potential”. Of course, no one has proven that this “enzyme potential” actually exists either. So there’s strike one and strike two.
To go ahead and put this horse out of its misery, humans have had control of fire for somewhere on the order of 500,000 to 1.5 million years. Yes, that’s a big spread and I’m being intentionally generous with the low end to nix the argument of first control of fire (currently accepted earliest evidence is 1.42 million years). It’s pretty easy to assume that early man figured out that cooking certain foods made them easier to digest, considering that we’ve evolved into the Earth’s dominant species.
Does Cooking Destroy Nutrients?
The reality is that humans started cooking food because it makes food more easily digestible, rather than making it more difficult to digest. There are some exceptions, but for the most part, this is true. And the only measure of how nutritious a food is is how well the body can digest it.
For instance, cooking a starchy food increases digestibility markedly, on the order of 2-12 times, depending on the preparation method. For vegetarians, this is particularly important. Protein digestibility of legumes, grains, and seeds are all enhanced by sprouting and cooking.
Garlic is another example. It contains two compounds of relevance here, one called allicin and the other known as diallyl sulfides. While allicin content is decreased by cooking, diallyl sulfides survive or are possibly enhanced by cooking and are responsible for garlic’s blood pressure lowering capabilities.We can also look at the tomato. Noted for its lycopene content, which is purported to decrease prostate cancer risk, people gobble up tomatoes by the truckload. Unfortunately, more lycopene is released from the tomato (or conversely, is more easily absorbed in the body) when it is cooked.
Some nutrients become more available and some are decreased or destroyed by heat. Vitamin C, for example, is highly unstable, easily leaching into cooking water or being broken down by heat, light, and air. Other water soluble vitamins, while easily leaching into water, are relatively stable under heat.We could continue all day with examples to prove that food should be cooked or food should be raw. Either viewpoint can be proven with carefully selected data points to fit one’s bias. But as you can see, there is no cut-and-dried rule. In many cases, cooked food is easier to digest and assimilate than raw food.
Are Anti-nutrients Destroyed By Cooking?
Most vegetables contain anti-nutrients of some sort. They are the plant’s evolved defensive mechanism to keep animals from eating the parts the plant doesn’t want eaten. For example, an apple tree doesn’t want you to eat the seeds in the apple, so the seeds contain anti-nutrients, in this case, cyanide. This serves to deter predators from chowing down on the seeds, preserving the symbiotic relationship of “you eat my apple and ‘deposit’ the seeds elsewhere”.
Grains and soybeans in particular are loaded with antinutrients. Eating soy in general (other than fermented types) and improperly prepared grains are both a bad idea, so to try eating either raw is a VERY bad idea.
Cooking helps eliminate some, but not all anti-nutrients. In the soy bean, the goitrogens, phytoestrogens, and phytates are all heat stable. On the other hand, trypsin inhibitors and lectins in some foods (taro, for example) are neutralized by cooking.
Again, there’s no hard and fast rule here. The best way to manage your anti-nutrient load is to eat a wide variety of foods, which will guarantee a spectrum of vitamins and minerals, while reducing the anti-nutrient load that can come from relying on a single dietary staple.
How To Cook Your Vegetables
Depending on the cooking method and the particular food, cooking can either enhance or destroy the nutrient availability in food. High temperature cooking is likely to drastically reduce availability of most water-soluble vitamins. Boiling in particular will leach out lots of vitamins from your vegetables. On the other hand, fat-soluble vitamins do just fine with boiling.
I usually lightly steam my vegetables, about 10 minutes max, such that they are still crisp, but warm and obviously no longer raw. Sometimes with greens, I’ll do a quick boil, bringing water to a boil, then dropping kale or mustard greens in for a minute, then draining. Obviously this isn’t an optimal method for vitamin retention, so I might rethink this practice a bit, opting instead for steaming.
Now, with soups and stews, you get vitamins and minerals leaching out into the stock, but then you eat the stock. It’s a win-win of improving the digestibility of the vegetables while also getting the nutrients, with the exception of those broken down by the heat of cooking.
An often neglected category of vegetables is the fermented ones, such as sauerkraut and kimchi. These foods harness the power of nature to begin the digestive process. At it’s heart, fermentation allows bacteria to eat the sugars available in a food and produce acid that creates a nice sour flavor as a by-product. When it comes down to it, you’re eating bacteria farts. Then again, you drink bacterial excrement every time you enjoy red wine, whiskey, beer, or any other alcohol; it’s all part of the fermentation process.
What results is a highly nutritious, probiotic-filled product with a nice salty tang and a bit of crunch. Fermented foods are eaten the world over, being prized additions to many cuisines.
Note that the sauerkraut you find in stores is typically pasteurized, which kind of defeats the purpose since you kill off all of the bacteria, including the good ones.
How I Eat My Vegetables
Since there are no real hard and fast rules about whether raw is better or cooked is better, I make sure that I get a mix of raw, cooked, and fermented vegetables in my diet. On a percentage basis, I’m probably around 40% raw, 40% cooked, and 20% fermented. I need to get more fermented vegetables into my diet as I feel that about 1/3 from each category is probably a good ratio. I have no scientific basis for that, but I think all three ways of eating vegetables have benefits.
So here’s the bulk of how I get my vegetables. I usually have a huge salad each day consisting of whatever type of lettuce I have on hand (mixed greens, green or red leaf, endive, etc) and some combination of carrots, radishes, cucumbers, green or red onions, and fresh herbs. It’s not always the same, but that’s the basics. That covers my raw intake for the most part. Sometimes I end up with a cabbage from my CSA that I’ll turn into a cole slaw of some sort.
Then, for dinner, I usually cook vegetables of some sort. I might quick boil some kale and mix it up with a carmelized onion and some tahini-lemon sauce (1/4 c tahini, 1/4 c lemon juice, 2 cloves minced garlic, blended). Or I might steam some broccoli or asparagus. Add in some cooked starch from the sweet potatoes I eat on a regular basis to keep my carb intake up and that’s the majority of my cooked veggie intake.
And finally, I try to keep a jar of sauerkraut around to get my fermented vegetables. I usually eat a bowl of this before tucking into my salad. Unfortunately, my last attempt was a bust and I ended up with salty, soggy cabbage instead of kraut. Oh well, that’s the nature of the beast.
One Last Thing About Nutrient Availability
Don’t forget that fat helps your body absorb the vitamins and minerals in your vegetables. A dry salad or a salad dressed with something that doesn’t contain any oil is less beneficial than a salad with olive oil on it, not to mention much less tasty.
I think the bottom line is to consume a variety of vegetables as they are in season, prepared in a variety of ways. From salads to soups, cold to hot side dishes, all promote your health in various ways. In the end, nutrient loss from cooking is a bit overblown, only amounting to 10-25% of most vitamins and virtually nothing in minerals. So eat your vegetables…cooked, raw, fermented. Don’t get paralyzed by concerns over vitamins.
For a lot more reading on this issue than I could hope to cover here, check out Beyond Veg.