The Truth About “anti-nutrients”
What’s good about leafy greens and beans and grains? Let me count the ways…
First, the obvious; leafy greens like spinach and kale provide a diverse range of insoluble fibers that reach the colon, serving as a nutrient source for beneficial bacteria, such as Bacteroidetes and Firmicutes. These symbiotic bacteria ferment the plant fiber producing short-chain fatty acids (SCFAs) that nourish the gut lining, reduce inflammation, and support overall gut health. The rich phytonutrient content in these vegetables promotes a balanced and resilient microbial community in your gut. Leafy greens like spinach and kale are rich sources of essential micronutrients, including vitamins such as vitamin A, for vision and immune function, vitamin K, important for blood clotting and bone health, vitamin C, an antioxidant supporting the immune system, and folate (Vitamin B9), necessary for DNA synthesis and cell division. Leaves also provide minerals like iron for oxygen transport, calcium for bone health, potassium regulating blood pressure, and magnesium for muscle and nerve function. Additionally, they contain polyphenols, antioxidants such as carotenoids (lutein, zeaxanthin) supporting eye health and flavonoids with antioxidant and anti-inflammatory effects.
Second, beans and whole grains like millet and quinoa are rich sources of dietary fiber, specifically soluble fiber, which supports digestive health and provides a food source for beneficial bacteria in the gut. This fiber helps regulate bowel movements, prevents constipation, and fosters a diverse microbial community. Beans and grains contain vitamins (B vitamins) and minerals (iron and zinc), which are important for energy metabolism, immune function, and the maintenance of healthy tissues. The resistant starch found in certain beans and whole grains acts as a prebiotic, promoting the growth of beneficial bacteria like Bifidobacteria and Lactobacilli in the colon. These bacteria contribute to the fermentation of the resistant starch, producing short-chain fatty acids that support gut health and have anti-inflammatory effects. Importantly, beans and whole grains have a low glycemic index, which means they have a gradual impact on blood sugar levels, providing sustained energy and contributing to weight management. Maintaining a healthy weight is linked to better overall health and a more favorable microbial profile in the gut.
What’s the deal with Oxalic acid? What even is oxalic acid?
Spinach and some other vegetables contain oxalic acid, which is a chemical compound that can form oxalate crystals. Oxalic acid can bind to minerals such as calcium forming insoluble complexes like calcium oxalate. This binding reduces the absorption of minerals by making them less available for absorption. Oxalic acid is not necessarily harmful, and eating a diet high in vegetables often gives you plenty of minerals, despite the presence of inhibitory compounds like oxalic acid. The good news is that cooking helps reduce oxalic acid content in leafy greens and improve mineral absorption. And when spinach, or other vegetable is consumed with an acid, the acid can bind to the oxalic acid, forming soluble complexes. This reduces the formation of insoluble calcium (or magnesium) oxalate crystals, making more minerals available for absorption in the digestive tract. Additionally, acidulation can help break down the cell walls of plant tissues, which may enhance the release of minerals and nutrients from the food, making them more accessible for absorption. Enhancing mineral absorption by eating vegetables with an acid sounds like a no-brainer because it is! Vegetables pair perfectly with delicious acids such as citrus and vinegars! The vegetables with the highest oxalic acid content are Spinach, Swiss chard, Beet Greens, Rhubarb, Beets, Sweet Potatoes.
What about phytic acid and lectins?
Phytic acid, or phytate, is a form of phosphorus found in many plants. Beans and grains contain phytic acid and also lectins. Lectins are a class of proteins that can bind to carbohydrates. Both phytic acid and lectins can inhibit nutrient absorption. Phytic acid, or phytate, can bind to minerals like calcium, iron, and zinc, forming insoluble complexes and reducing their bioavailability, just like oxalic acid does. The good news is that soaking, sprouting, and fermentation are easy methods that can help mitigate the impact of binding compounds in beans and grains, improving nutrient absorption and making these foods more nutritionally beneficial. Soaking and sprouting beans and grains easily reduces the levels of phytates and lectins. During soaking and sprouting, enzymes are activated, which break down phytic acid and reduce lectin levels while the seed prepares to become a plant. Fermentation is another method that can decrease phytate levels in beans and grains. During the process of fermentation, bacteria and yeast produce enzymes such as phytase that break down phytic acid and lectins present in foods. These microorganisms also produce protease enzymes that break down proteins, including lectins, into individual amino acids. The amazing part about this process is that this enzymatic breakdown transforms lectins from potentially inhibitory compounds into valuable sources of amino acids for the human host. The liberated amino acids, including essential ones like phenylalanine, valine, and lysine, become readily available for absorption, enhancing the nutritional value of the fermented food and reducing the potential inhibitory effects of lectins on mineral absorption. Yet another reason why fermentation is a nutritional powerhouse! Ferment almost anything and it becomes healthier! Fermentation also promotes the growth of beneficial bacteria and produces bioactive compounds that can enhance the nutritional profile and digestibility of the fermented food.
How are bacteria involved with oxalate degradation?
The oxalate in the body has two sources: oxalate from dietary sources or internally, mainly in the liver, using various dietary precursors such as glyoxalase, ascorbic acid, and certain amino acids. This internal oxalate production significantly affects urine oxalate levels and the formation of calcium oxalate kidney stones. Glyoxylate is a key precursor to oxalate production, derived from the amino acids phenylalanine, glycine, hydroxyproline, tryptophan, pentose sugars, glucose, fructose, ethanolamine, and glycolate metabolism in the body. Many bacteria in our gut can break down oxalate, potentially reducing the formation of kidney stones. However, the makeup of the gut microbiome varies greatly among individuals, with around four hundred different bacterial species present. Oxalate-degrading bacteria, when present, can lower urine oxalate levels by up to 40%, leading to a significant decrease in kidney stone formation. The composition of gut bacteria varies between individuals but tends to stay consistent within each person. Changes in diet and antibiotic use can affect gut bacteria over time. The absence of these bacteria increases the risk of hyperoxaluria and kidney stones. Antibiotics can reduce oxalate-degrading bacteria populations, potentially increasing the risk of kidney stone formation. O. formigenes, a bacteria that consumes oxalate, is found in the human digestive system. It is susceptible to antibiotics and may proliferate more in people without kidney stones. Variables affecting the activity of oxalate-degrading bacteria include pH, where optimal conditions for degradation occur at pH 5.5 and can increase with higher oxalate concentration. Glucose and sucrose concentrations affect bacterial growth and oxalate degradation rates. Yeast extract is essential for the growth of O. formigenes, while bacterial age affects linoleic acid production. Inulin, a prebiotic, increases bacterial growth and oxalate degradation, with higher concentrations leading to better degradation rates.
For optimal nutrient absorption, incorporate acidity with your meals through citric acids such as fruit or acetic acid sources like raw apple cider or balsamic vinegar. Vitamin C (ascorbic acid) also enhances the absorption of non-heme iron in plant foods by converting ferric iron (Fe^3+) to more soluble ferrous iron (Fe^2+). Vitamin C achieves this by reducing ferric iron in the stomach, forming soluble complexes with iron to prevent inhibitors, and improving the uptake of non-heme iron across the intestinal lining. To maximize these benefits, I recommend eating vitamin C-rich foods with iron-rich plant foods in the same meal. Additionally, you can maximize the nutrient content of foods by adopting traditional practices such as soaking, sprouting, and fermenting beans, grains, and seeds like raw almonds. These methods not only enhance nutritional value but also provide a practical approach to getting the most bang for your buck out of your dietary choices. I am here to help you learn to eat this way!
