Carbohydrates play a predominant role in human diets, comprising some 40-75% of energy intake. Carbohydrates are formed in plants when carbons are bonded with oxygen and hydrogen to form chains of varying complexity. The complexity of the chains determines the carbohydrate classification. Mono-and disaccharides are “simple” carbohydrates. Polysaccharides are classified as “complex.”
However, all carbohydrates are broken down into monosaccharides before being converted to glucose. Glucose is necessary for brain function, the maintenance of the central nervous system, and intense physical activity. Unfortunately, for most, carbohydrate consumption often exceeds daily needs; additionally, carbohydrate consumption is dominated by two sources that have undeniably negative health consequences: refined flours and sugars.
Refined flours, made from refined grains, do not contain the germ and bran of the seed and thus are absent in many important nutrients. They simply contain the endosperm, a source of carbohydrate, plant protein, and some B Vitamins. Refined sugar, like beet and cane sugar and high fructose corn syrup, have a well-documented negative, potentially toxic effect on human health. These carbohydrates are what may be called “bad” carbs.
Can one food be inherently “good” while another is “bad”? I think this attitude in itself is unhealthy. The point of dividing carbohydrates into these categories is to highlight the potential health impact of eating well-documented “good,” “bad,” and “ugly” foods. Armed with the knowledge, you can make decisions that positively influence your life.
Vegetables are our best source of carbohydrates. Not only do vegetables provide an easily absorbed form of carbohydrate, they provide important phytonutrients, or “plant nutrients,” the pigments and bitter tasting compounds found in plants. Once assumed to be of benefit to plants only (in terms of self-protection and growth), these nutrients have proved to be tremendously beneficial to humans, too. Under scientific scrutiny, phytonutrients have turned out to be potent antioxidants, which, in humans, can help prevent cancer, reduce inflammation, and protect your cells from the oxidizing stress of modern life.
Of course, vegetables vary in carbohydrate content; the healthiest vegetables, indeed the healthiest foods on the planet, also happen to be low-carbohydrate vegetables: green vegetables like kale, lettuce, spinach, and herbs; cruciferous vegetables like broccoli, cauliflower, and cabbage; onions and garlic; and popular summer vegetables like cucumbers, zucchini, tomatoes, and peppers.
High-carbohydrate vegetables include potatoes, sweet potatoes, beets, carrots, winter squash, and jicama. These higher-carbohydrate vegetables can also play an important role in the diet—to a point.
Last year, Dr. Mercola reported on a public debate between two nutritional experts, Dr. Paul Jaminet and Dr. Ron Rosedale. Dr. Rosedale, citing evidence on the negative, potentially toxic, consequences of glucose, stated that the notion of a “safe starch” does not exist, and that all starchy carbohydrates should be avoided. Dr. Jaminet, on the other hand, believed some people need a small amount of starchy vegetables in their diets. The debate is fascinating, as it speaks directly to the role carbohydrates play in the maintenance of health. After all, as stated above, glucose is necessary. Those on ultra-low carbohydrate diets might experience symptoms similar to Dr. Mercola himself, a long-time advocate of ultra-low carbohydrate diets:
"When I eliminated…grains and starchy vegetables, I actually experienced…negative effects. My energy levels declined considerably, and my cholesterol…normally about 150, rose to over 200…I was suffering a glucose deficiency and this can trigger lipoprotein abnormalities. It also seemed to worsen my kidney function."
After evaluating Dr. Jaminet’s and Dr. Rosedale’s debate, Dr. Mercola now recommends the following:
"My conclusion is that there is a certain minimum carbohydrate threshold that you should not drop below. The sweet spot for most is 20 to 30 percent of your diet as carbs, but most likely 25 to 30 percent. Most of those calories can come from non-starchy vegetables, but you'll probably need some starchy carbs, such as white potatoes…carrots and squash."
Perhaps the primary benefit of high-carbohydrate vegetables is their ease of digestibility. Most people eat, enjoy, and fully digest, high-starch vegetables like potatoes or sweet potatoes.
Unfortunately, the same cannot necessarily be said of grains. For those who suffer sensitivity to grains, high-starch vegetables just might be a key to health.
Many experts agree that whole grains are the healthiest carbohydrate choice. The usable part of a grain is called the kernel, and the kernel is comprised of three major parts—the germ, bran and starchy endosperm. For a grain to be considered “whole,” it must contain the germ, bran and starchy endosperm. Each part of the grain contributes different nutrients. The germ contains B Vitamins, Vitamin E, trace minerals, essential fatty acids, and phytochemicals. The bran contains fiber, B Vitamins, and trace minerals. The endosperm contains plant protein and some B Vitamins.
Despite the popularity of this view, convincing evidence exists to suggest grains, and whole grains, might not be the best choice for some people. Why? Anti-nutrients. To avoid insects, foraging animals, and humans, plant species have evolved certain protective anti-nutrients. Mark’s Daily Apple has posted some intriguing reports on anti-nutrients. As the site states:
"A workable balance developed between plants that were able to safeguard their species’ survival and the “pest” patrons that were able to benefit from the plants’ nutrition but learned to partake more sensibly from their supply. Given that our primal forefolk foraged widely and ate a surprisingly diverse diet, the system worked."
Lectins, an anit-nutrient, are widespread in the plant kingdom, but virtually unknown by consumers: the people eating the lectins. This is unfortunate. Dr. Mercola notes:
"Certain lectins, including those in wheat, bind to receptor sites on your intestinal mucosal cells and interfere with the absorption of nutrients across your intestinal wall and into your blood…Lectins can promote inflammation, stimulate a hyper-immune response, and increase blood viscosity."
Another pervasive anti-nutrient is gluten. “Gluten” from the Latin word for glue, is the substance that binds bread and baked goods together. Wheat, rye, and barley include gluten. If you are sensitive to gluten, it might interfere with the breakdown and absorption of nutrients, including nutrients from other foods in the same meal.
A Few Special Grains
Quinoa: A recently rediscovered ancient “grain” native to South America, quinoa is actually a seed. Once called “the gold of the Incas,” quinoa was known to increase the stamina of Incan warriors. Not only is quinoa high in protein, but the protein it supplies is complete protein, meaning that it includes all nine essential amino acids. Quinoa is especially well-endowed with the amino acid lysine, which is essential for tissue growth and repair.
Buckwheat: Energizing and nutritious, buckwheat, a fruit, is available throughout the year and can be served as an alternative to rice or made into porridge. It has been shown to benefit blood sugar control as well as the cardiovascular system. It is also a potent anti-cancer food.
Spelt: A wonderfully nutritious and ancient grain with a deep nutlike flavor, spelt is a cousin to wheat that is recently receiving renewed recognition. Spelt is an ancient grain that traces its heritage back long before many wheat hybrids. Many of its benefits come from this fact: it offers a broader spectrum of nutrients compared to many of its more inbred cousins in the Triticum (wheat) family. Spelt features a host of different nutrients. It is an excellent source of vitamin B2, a very good source of manganese, and a good source of niacin, thiamin, and copper.
Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood. This glucose is then stored as glycogen or fat in the liver and muscles. Insulin's primary role, then, is not necessarily to lower sugar, but to take the extra energy and store it for future times of need. Your body produces insulin in response to carbohydrate consumption—the more carbohydrates (including the sugars in carbohydrates) you eat, the more insulin your body produces and the more glycogen and/or fat is stores in your liver and muscles.
Since your body produces insulin in response to carbohydrate consumption, and since insulin is a storage hormone that stores glucose as fat in the liver and muscles, the “bad” carbohydrates might be considered those that stimulate the highest secretion of insulin. This means two things: any carbohydrate, if eaten in excess, can be considered bad; likewise, any carbohydrate that produces a correspondingly large production of insulin can be considered bad. As discussed above, these latter bad carbohydrates include refined grains and sugars, but they might also include fruit, eaten to excess.
Your body metabolizes fructose in a much different way than glucose. The entire burden of metabolizing fructose falls on your liver. People are consuming fructose in enormous quantities, which has made the negative effects much more profound. Once again, Dr. Mercola:
"Glucose is the form of energy you were designed to run on. Every cell in your body, every bacterium…uses glucose for energy. If you received your fructose only from vegetables and fruits (where it originates)…you’d consume about 15 grams per day—a far cry from the 73 grams per day the typical adolescent gets from sweetened drinks. In vegetables and fruits, it’s mixed in with fiber, vitamins, minerals, enzymes, and beneficial phytonutrients, all which moderate any negative metabolic effects. It isn’t that fructose itself is bad -- it is the MASSIVE DOSES you’re exposed to that make it dangerous."