Perhaps the most striking health benefit provided by quinoa is its overall nutrient richness. When the nutrient composition of this food is analyzed in depth, the results are unusual and striking. While quinoa can be eaten in the same way as a grain, or ground into flour like is so commonly done with grains, it lacks some important nutritional shortcomings of grains.
One of the shortcomings overcome by quinoa involves its protein content. Most grains are considered to be inadequate as total protein sources because they lack adequate amounts of the amino acids lysine and isoleucine. The relatively low level of both lysine and isoleucine in the protein of grains is what causes these amino acids to be considered as the limiting amino acids (LAAs) in grains. In other words, these LAAs prevent grains from serving as complete protein sources in our diet. By contrast, quinoa has significantly greater amounts of both lysine and isoleucine (especially lysine), and these greater amounts of lysine and isoleucine allow the protein in quinoa to serve as a complete protein source.
In terms of fat content, quinoa once again overcomes some of the shortcomings of most grains. Since it takes nearly 350 calories' worth of whole wheat to provide 1 gram of fat, whole wheat is not generally regarded as a significant source of fat, including essential fatty acids or heart-healthy monounsaturated fats (like oleic acid). By contrast, since it only takes 63 calories' worth of quinoa to provide 1 gram of fat, quinoa is typically considered to be a valuable source of certain health-supportive fats. About 28% of quinoa's fatty acids come in the form of oleic acid, a heart-healthy monounsaturated fat, and about 5% come in the form of alpha-linolenic acid or ALA—the omega-3 fatty acid most commonly found in plants and associated with decreased risk of inflammation-related disease.
Neither quinoa nor any grains qualify as good vitamin E sources in our WHFoods rating system. However, in the case of quinoa, or rating system does not do full justice to the fact that quinoa contains significant amounts of certain tocopherols (vitamin E family members) largely absent from most grains. For example, one cup of quinoa provides 2.2 milligrams of gamma-tocopherol—a form of vitamin E that has been more closely associated with certain anti-inflammatory benefits in health research. Quinoa is also a good source of RDA nutrients like folate, zinc, and phosphorus in contrast to whole wheat, which does not qualify as a good source in our rating system.
Quinoa is an equally impressive food in terms of its overall phytonutrient benefits. In many Central and South American countries, the leaves of the quinoa plant are valued for their betacyanin pigments, which provide some of their bright reddish shades. But even the seeds themselves can be phytonutrient-rich and can provide significant amounts of antioxidants like ferulic, coumaric, hydroxybenzoic, and vanillic acid.
The antioxidant flavonoids quercetin and kaempferol are also especially plentiful in quinoa. In fact, the concentration of these two flavonoids in quinoa can sometimes be greater than their concentration of high-flavonoid berries like cranberry or lingonberry.
Considered in combination, these diverse nutrient benefits of quinoa give it uniqueness among grain-related foods. For us, this high overall level of nourishment provided by quinoa may qualify as its greatest health benefit.
Most of the quinoa studies that we've seen in this area have been animal studies. However, we believe that the preliminary indications for humans are very promising. Research has shown the ability of daily quinoa intake to lower levels of inflammation in fat (adipose) tissue in rats and in the linings of their intestine as well.
We're not surprised at either of these results because a wide range of anti-inflammatory nutrients is already known to be present in quinoa. This list of anti-inflammatory nutrients includes phenolic acids (including hydroxycinnamic and hydroxybenzoic acids), members of the vitamin E family like gamma-tocopherol, and cell wall polysaccharides like arabinans and rhamnogalacturonans.
Somewhat more controversial in this anti-inflammatory nutrient list are the saponins found in quinoa. Saponins are the bitter tasting, water-soluble phytonutrients found in the outer seed coat layer of quinoa. (More specifically, the saponins found in quinoa are derived from hederagenin, oleanic acid, phytolaccagenic acid, and serjanic acid.) The quinoa saponins have been shown to have both anti-inflammatory and antioxidant properties. However, soaking, boiling, and milling can reduce their presence, and, in general, this reduced presence is usually regarded as a good thing since it can make the quinoa much more enjoyable for most people to eat. In research to date, the relationship between and anti-inflammatory benefits of quinoa and saponin levels has yet to be clarified. However, even though more research is needed in this particular phytonutrient area, the list of anti-inflammatory nutrients in quinoa remains impressive.
We have yet to see large-scale human studies on intake of quinoa and risk of type 2 diabetes or risk of cardiovascular disease. However, we would expect such studies to show significantly reduced risks. With respect to type 2 diabetes, quinoa simply has too many things in common with other foods known to decrease risk. At the top of the list here would be its fiber and protein content. Quinoa is a good source of fiber—one of the key macronutrients needed for health blood sugar regulation. It also provides outstanding protein quality, even in comparison to commonly-eaten whole grains. Strong intake of protein and fiber are two dietary essentials for regulation of blood sugar. Because chronic, unwanted inflammation is also a key risk factor for development of type 2 diabetes, the diverse range of anti-inflammatory nutrients found in quinoa also make it a great candidate for diabetes risk reduction.
Animal studies have already demonstrated the ability of quinoa to lower total cholesterol and help maintain levels of HDL cholesterol (the "good" cholesterol). While we would expect these results in humans as well, we would also expect the anti-inflammatory nutrients in quinoa to help protect human blood vessels from inflammatory damage. Protection of this kind would also provide reduced risk of many cardiovascular diseases, including atherosclerosis. We expect to see future, large-scale human studies demonstrating the benefits of quinoa for risk reduction in this area of cardiovascular disease.
The antioxidant and anti-inflammatory phytonutrients in quinoa also make it a likely candidate for cancer risk reduction in humans. Given the preliminary animal results involving the digestive tract, risk reduction for colon cancer may turn out to be a special area of interest.
A final area of likely benefit involves decreased risk of allergy—especially for individuals who have adverse reactions to certain grains and seek practical alternatives. Already, several public organizations have recommended quinoa as a substitute for wheat whenever the avoidance of this gluten-containing grain is required. The low-allergy potential of quinoa—coupled with its relatively high digestibility—has also made it a food of special interest in the diet of children and toddlers.