Since man first learned to harness the power of fire, we’ve been using it to transform our foods. And this transformation has not only helped us to advance the culinary arts, it has helped us to advance as a species.
Even in tropical regions with lush vegetation, it is estimated that humans have been cooking our foods for at least 200,000 years.
However, despite our long and beneficial history of transforming our food through cooking, certain circles believe that a “raw food diet” is the best diet for human health. Proponents of raw foods claim that “going raw” promotes weight loss, makes you look younger, improves detoxification and fights disease.
And while switching from the Standard American Diet (rife with processed sugar, artificial ingredients and man-made fats) to a diet that includes more vegetables and fruits can confer a wide range of health benefits, there is much more to the story.
Putting the Heat on a Raw Diet
It is true that high-heat cooking can destroy some nutrients (especially some of the water-soluble vitamins). Heat can also diminish certain antioxidants and damage fats, specifically polyunsaturated fats. High temperature cooking and baking can also cause dangerous compounds to form (like acrylamide in carbohydrate-rich foods, lipid oxidation products in over-heated oils and heterocyclic amines in charred meats).
However, more often than not, heat is your friend when it comes to health. Some of nature’s most powerful and protective antioxidants –including beta-carotene, lycopene, lutein and astaxanthin – only become “bio-available” to the body when they are unlocked by heat.
Without it, they pass through the body without conferring much (if any) of their antioxidant value.
But what about all of the healthy enzymes found in raw plant foods? Doesn’t cooking destroy these compounds?
It is true that enzymes are heat-sensitive. That means they are usually destroyed by cooking. But they are also very sensitive to hydrochloric acid – the digestive substance found in the stomach. That means that most of the enzymes from plant foods are destroyed during the digestive process anyway. They don’t get much farther than the first section of the small intestine.
Can a Raw Diet Cause Kidney Stones and Gout?
In addition to missing out on the benefits of many lipid-soluble nutrients, a raw diet can also contribute to muscle pain, kidney stones, gout and calcium deficiencies.
The reason? An excess of oxalic acid.
Oxalic acid is found in leafy green veggies like kale, spinach, collards, chard and parsley. It acts as a defense mechanism for plants – thwarting attacks by hungry bugs. This compound also has some unhealthy effects on humans.
During digestion, oxalic acid binds to calcium – making it unusable by the body. It can also form crystals that get lodged in muscles or extremities (as is the case with gout). And if oxalic acid crystals form in the kidneys, painful kidney stones can develop.
But a little heat can fix all of this. In fact, according to a recent study published in Agricultural Food Chemistry, lightly steaming (and draining) veggies that are high in oxalic acid can significantly reduce this problematic substance.
And if you’re concerned about thyroid health, here’s another reason to get out your sauté pan…
Attack of the Goitrogens: Raw Veggies and Your Thyroid
Compounds called goitrogens found in cruciferous veggies (like broccoli, kale, Brussels sprouts, kohlrabi, cauliflower) have been found to have detrimental effects on the thyroid.
Goitrogens block the body’s manufacture of thyroid hormones. They also hamper iodine metabolism, reducing thyroid function. And because the thyroid is the “master of your metabolism”, this means a raw diet may actually increase the risk of weight gain and other hormonal problems for some people.
But lightly cooking or fermenting cruciferous veggies can significantly reduce the substances that can wreak havoc on this important metabolic gland.
Why Raw Isn’t Natural: The Ancestral Record
Along with the fact that a diet that is excessively high in certain raw foods can cause a number of health issues, you should also take into consideration our ancestor’s diets.
No known human culture has ever attempted to subsist purely on raw plant foods. The reason? A raw diet is only made possible by modern conveniences like refrigeration and year-round access to vegetation.
When it comes to raw foods, take heed. Cook carotenoid-rich foods (including sweet potatoes, winter squash, carrots, tomatoes) to unlock their full nutritional bounty. And it is best to enjoy leafy greens and cruciferous veggies lightly steamed or fermented for maximum benefit.