19 Jan 2018 Grains and Legumes and Antinutrients, Oh My!
Despite the growing anti-grain movement, it’s still recommended that we consume 5-8 ounce equivalents or more of grains per day, and whole grains are still the face of the typical healthy diet (1).
Mainstream nutrition recommendations tell us that whole grains, pseudograins, and legumes are heart-healthy and promote a healthy weight. These food groups include foods like:
- Wheat, corn, rye, barely, rice, millet, oats (grains)
- Quinoa, amaranth, buckwheat (pseudograins)
- Beans, soy, lentils, peanuts (legumes)
On the other hand, refined grains are the ones blamed for obesity, diabetes, and heart disease.
Holy Whole Grains vs. Evil Refined Grains
Let’s start with the basics.
Grains, pseudograins, and legumes are all seeds, which have 3 main components: bran, germ, and endosperm. The bran and germ contain most of the fiber and “nutrients,” and the endosperm is the carbohydrate-dense portion.
A whole grain is still intact – it contains all 3 of these components, while refined grains are stripped of the germ and bran, leaving only the endosperm.
So, the only difference between the “healthiest-of-all-foods” whole grains and the “inflammation-diabetes-obesity-and-heart-disease-causing” refined grains are the fiber and the “nutrients,” while the starch-containing endosperm is the same.
And, like whole grains, the “heart-healthy” pseudograins and legumes are full of fiber and “nutrients.”
But, it turns out that the fibers and “nutrients” found in these foods might not be so beneficial after all, leaving their supposed health-promoting effects in question.
Grains, Legumes, and Fiber
Whole grains, pseudograins, and legumes contain both soluble and insoluble fibers.
Soluble fibers are considered prebiotics because they feed our gut bacteria, whereas insoluble fibers are not digested by our gut bacteria and help to move food through our guts.
These fibers are considered beneficial because of ability to keep us full for longer, their prebiotic effects, and their colon cleansing effects.
But, these effects aren’t always so beneficial.
Keeping us full for longer might be favorable if we wanted to eat less, but eating less isn’t really beneficial unless we want to deprive ourselves of energy (Why “Eat Less and Exercise More” is the WORST Advice for Fat Loss and Health).
The ability for soluble fibers to feed our gut bacteria may sound healthy when it’s phrased as “feeding our good bacteria,” but this is more like wishful thinking. These fibers do feed our gut bacteria, but they feed the bad ones in addition to the good ones.
This isn’t a problem if our gut function and microbiome composition are optimal. But, if they aren’t optimal, which is extraordinarily common in modern times, this will exacerbate any gut dysfunction that’s going on.
(Fun fact: the gas that’s commonly associated with eating beans is a product of a suboptimal microbiome consuming soluble fiber)
On the other hand, the ability for insoluble fibers to move food through our gut is beneficial because gut motility is important for healthy gut function. But, this is a relatively trivial benefit in the context of grain consumption.
Grains, Legumes, and (Anti)nutrients
Whole grains, pseudograins, and legumes are touted for their nutrient content, specifically their vitamins, minerals, and protein. But when we consider their antinutrient content, their nutrient value is really pretty poor.
As I mentioned earlier, grains, pseudograins, and legumes are seeds. Seeds are an extraordinarily important part of plants – they’re needed for plants to reproduce. The nutrients in seeds aren’t meant for us, they’re meant to be used for growing a new plant.
Plants can’t protect their valuable seeds by running from predators or attacking them with sharp claws or teeth. Instead, their seeds have chemical defenses – compounds that protect their nutrients and cause harm to animals who eat them. These compounds are commonly referred to as antinutrients.
There are several types of antinutrients, including lectins, phytic acid (phytates), oxalic acid (oxalates), enzyme inhibitors, and saponins, each with unique harmful effects.
Lectins are probably the most damaging and well-known antinutrients. You’ve probably heard of the most infamous lectin, gluten. Lectins inhibit nutrient absorption, cause bacterial overgrowth and systemic stress and inflammation, and damage our gut barrier, causing it to become permeable or “leaky” (2, 3, 4, 5, 6).
Gut permeability, or “leakiness,” allows undigested food particles and toxins to travel directly into the bloodstream, which can impair energy production and contribute to stress and inflammation (7, 8).
Phytic Acid and Oxalic Acid
Phytic acid and oxalic acid bind with calcium, magnesium, zinc, copper, potassium, iron, and other minerals, blocking their digestion and absorption in our guts and inhibiting our ability to use them (9, 10, 11). These minerals are vital for many processes, one of the most noteworthy being energy production.
Enzyme inhibitors block the enzymes in our guts that digest protein and starch, which prevents the digestion and absorption of protein and starches in the grains, pseudograins, and legumes, as well as in other foods we happen to be eating with them (9, 12, 13). Phytic acid also blocks some of these enzymes, further inhibiting the digestion of protein and starch (14, 15).
Saponins, which are found mostly in pseudograins and legumes, inhibit protein-digesting enzymes, inhibit thyroid function (the regulator of our metabolism), and bind with and lower cholesterol (this isn’t beneficial, as we might be led to believe – I explain why here) (16, 17, 18).
Antinutrients No More
Somehow, the mainstream has found ways to spin the harmful effects of antinutrients into benefits. Impairing energy production and contributing to inflammation is considered “boosting immune function,” impairing starch digestion is considered “managing blood sugar,” and reducing cholesterol is, well, just reducing cholesterol, but this isn’t beneficial like we’ve been told.
If you ask me, it’s pretty clear that whole grains and legumes aren’t the health foods they’ve been made out to be. If anything, they appear to be worse than their obesity-, diabetes-, and heart disease-causing counterparts, refined grains. And this isn’t to mention the pesticides and GMOs that are ubiquitous among these crops.
But, it’s not all bad. In fact, grains and legumes can be prepared in ways that negate many of their negative effects. Cooking can deactivate a few of the antinutrients in these foods, but the traditional preparations of soaking, sprouting, and fermenting significantly reduce their antinutrient content, and may even alter their fiber composition (9, 19).
But if that doesn’t suit your fancy, you can skip these foods altogether!
Grains are most certainly not a necessary part of a healthy diet like they’ve been made out to be. Fruits and starch-containing foods that aren’t grains, including roots (carrots, yuca, turnips, etc.), tubers (potatoes and sweet potatoes), and vegetables in the gourd family (like squash and zucchini), are all great sources of carbohydrates with few antinutrients, if any.
(Note: some of these foods, like potatoes, do have antinutrients. But, they’re housed in the skins which can be easily removed.)
Also, while it is a grain, white rice is a relatively antinutrient-free carbohydrate source. This is because it’s stripped of its bran and hull, the parts of brown rice that contain most of the antinutrients.
Does all of this mean that if you eat any non-traditionally prepared grains, pseudograins, or legumes you can say goodbye to your health?
Of course not. But it does mean that their promotion as “health foods” is not supported, and we may want to reconsider how much of them we’re eating.
- “All About the Grains Group.” Choose MyPlate, USDA, 3 Nov. 2017, www.choosemyplate.gov/grains.
- Vasconcelos, Ilka M., and José Tadeu A. Oliveira. “Antinutritional properties of plant lectins.” Toxicon: official journal of the International Society on Toxinology, 44, no. 4, 2004, pp. 385–403. doi:10.1016/j.toxicon.2004.05.005.
- Banwell, J. G., et al. “Bacterial overgrowth by indigenous microflora in the phytohemagglutinin-fed rat.” Canadian journal of microbiology, 34, no. 8, 1988, pp. 1009–13.
- Punder, Karin de, and Leo Pruimboom. “The dietary intake of wheat and other cereal grains and their role in inflammation.” Nutrients, 5, no. 3, 2013, pp. 771–87. doi:10.3390/nu5030771.
- Sjölander, A., et al. “The effect of concanavalin A and wheat germ agglutinin on the ultrastructure and permeability of rat intestine. A possible model for an intestinal allergic reaction.” International archives of allergy and applied immunology, 75, no. 3, 1984, pp. 230–36.
- Greer, F., and A. Pusztai. “Toxicity of kidney bean (Phaseolus vulgaris) in rats: Changes in intestinal permeability.” Digestion, 32, no. 1, 1985, pp. 42–46.
- Bischoff, Stephan C., Giovanni Barbara, Wim Buurman, Theo Ockhuizen, Jorg-Dieter Schulzke, Matteo Serino, Herbert Tilg, Alastair Watson, and Jerry M. Wells. “Intestinal Permeability – a New Target for Disease Prevention and Therapy.” BMC Gastroenterology1 (2014): 189.
- Crouser, Elliott D., et al. “Endotoxin-induced mitochondrial damage correlates with impaired respiratory activity.” Critical care medicine, 30, no. 2, 2002, pp. 276–84.
- Soetan, K. O., and O. E. Oyewole. “The need for adequate processing to reduce the anti-nutritional factors in plants used as human foods and animal feeds: A review.” vol. 3, no. 9, 2009, pp. 223–32.
- Nävert, B., et al. “Reduction of the phytate content of bran by leavening in bread and its effect on zinc absorption in man.” The British journal of nutrition, 53, no. 1, 1985, pp. 47–53.
- Bohn, Torsten, et al. “Phytic acid added to white-wheat bread inhibits fractional apparent magnesium absorption in humans.” The American journal of clinical nutrition, 79, no. 3, 2004, pp. 418–23.
- Ryan, C. A. “Protease Inhibitors in Plants: Genes for Improving Defenses Against Insects and Pathogens.” Annual Review of Phytopathology, 28, no. 1, 1990, pp. 425–49. doi:10.1146/annurev.py.28.090190.002233.
- Sarwar Gilani, G., et al. “Impact of antinutritional factors in food proteins on the digestibility of protein and the bioavailability of amino acids and on protein quality.” The British journal of nutrition, 108 Suppl 2, 2012, S315-32. doi:10.1017/S0007114512002371.
- Singh, Madhav, and A. D. Krikorian. “Inhibition of trypsin activity in vitro by phytate.” Journal of Agricultural and Food Chemistry, 30, no. 4, 1982, pp. 799–800. doi:10.1021/jf00112a049.
- Deshpande, S. S., and Munir Cheryan. “Effects of Phytic Acid, Divalent Cations, and Their Interactions on α-Amylase Activity.” Journal of Food Science, 49, no. 2, 1984, pp. 516–19. doi:10.1111/j.1365-2621.1984.tb12456.x.
- Liener, I. E. “Implications of antinutritional components in soybean foods.” Critical reviews in food science and nutrition, 34, no. 1, 1994, pp. 31–67. doi:10.1080/10408399409527649.
- Kimura, S., et al. “Development of malignant goiter by defatted soybean with iodine-free diet in rats.” Gan, 67, no. 5, 1976, pp. 763–65.
- Sidhu, G. S., and D. G. Oakenfull. “A mechanism for the hypocholesterolaemic activity of saponins.” The British journal of nutrition, 55, no. 3, 1986, pp. 643–49.
- Chavan, J. K., and S. S. Kadam. “Nutritional improvement of cereals by sprouting.” Critical reviews in food science and nutrition, 28, no. 5, 1989, pp. 401–37. doi:10.1080/10408398909527508.
- Peat, Ray, Dr. “Vegetables, etc. – Who Defines Food?” Retrieved from http://raypeat.com/articles/articles/vegetables.shtml.