Phytates: Hidden Dangers in Healthy Foods

Thinking you are eating a very healthy diet?  You may be, but there may be some really important compounds you are unaware of that can be robbing you of many of the beneficial nutrients of those very same foods.  Read on to find out more.

Phytates, or phytic acid, are naturally occurring compounds found in many plant seeds, especially in grains and legumes. They are recognized for their role in the storage of phosphorus in plants and have garnered significant attention in nutritional science due to their impact on mineral bioavailability. Let’s take a look at the chemistry of phytates, their dietary sources, nutritional implications, health benefits, and potential drawbacks, supported by relevant scholarly references.

Chemistry of Phytates

Phytic acid (myo-inositol hexakisphosphate) is a unique compound consisting of an inositol ring bound to six phosphate groups. This structure enables phytates to chelate essential minerals such as calcium, iron, and zinc, forming insoluble complexes that can impact their bioavailability in the human diet. The chemical behavior of phytates under various physiological conditions has been extensively studied, highlighting their dual role as both beneficial and potentially problematic dietary components (Raboy, 2001)[1].

Dietary Sources of Phytates

Phytates are predominantly found in seeds, nuts, legumes, and whole grains. High concentrations are particularly noted in foods such as wheat bran, rice bran, soybeans, and lentils. The levels of phytates in these foods can vary based on factors like the variety of the plant, soil conditions, and processing methods. The traditional methods of food preparation, such as soaking, fermenting, and sprouting, have been shown to reduce phytate content and improve mineral bioavailability (Reddy et al., 1982)[2].

It’s Not ALL Bad News:
Nutritional Implications of Phytates

Mineral Bioavailability

One of the primary concerns with dietary phytates is their ability to bind essential minerals, thereby reducing their absorption in the gastrointestinal tract. Studies have demonstrated that high-phytate diets can lead to deficiencies in minerals such as zinc, iron, and calcium, which are critical for various physiological functions (Lonnerdal, 2000)[3]. This issue is particularly relevant in populations that rely heavily on plant-based diets and have limited access to diverse food sources.

Protein Digestibility

Phytates have also been found to influence protein digestibility. By interacting with proteins and enzymes, phytates can inhibit the activity of proteases, thus affecting protein utilization. However, the extent of this interaction and its nutritional impact can vary based on the dietary context and overall protein intake (Eladawy, 2002)[4].

Health Benefits of Phytates

Despite concerns about mineral bioavailability, phytates have been recognized for their potential health benefits. They possess antioxidant properties, play a role in cancer prevention, and contribute to the regulation of blood glucose and lipid levels.

Antioxidant Properties

Phytates can act as antioxidants, scavenging free radicals and protecting cellular components from oxidative damage. This antioxidant activity is attributed to their ability to chelate iron, which catalyzes the formation of reactive oxygen species. Research has shown that phytate-rich diets can enhance antioxidant status and reduce oxidative stress in humans (Graf et al., 1987)[5].

Cancer Prevention

The role of phytates in cancer prevention has been a subject of considerable research. Phytates have been observed to inhibit the proliferation of cancer cells and induce apoptosis in various cancer models. Their anticancer effects are thought to be mediated through multiple mechanisms, including the inhibition of cell signaling pathways and the modulation of gene expression (Vucenik & Shamsuddin, 2003)[6].

Regulation of Blood Glucose and Lipid Levels

Phytates have also been implicated in the regulation of blood glucose and lipid levels. By slowing down the digestion and absorption of carbohydrates, phytates can help modulate postprandial blood glucose spikes. Additionally, they have been shown to lower serum cholesterol and triglyceride levels, contributing to cardiovascular health (Yoon et al., 1983)[7].

Potential Drawbacks of Phytates

While the health benefits of phytates are noteworthy, their potential drawbacks should not be overlooked. The primary concern remains their impact on mineral absorption, particularly in populations at risk of deficiencies. Furthermore, the extent to which phytates affect nutrient bioavailability can vary based on individual dietary habits and overall nutritional status.

Strategies to Mitigate Negative Effects

Several strategies can be employed to mitigate the negative effects of phytates on mineral absorption. These include dietary diversification, food processing techniques (such as fermentation, soaking, and sprouting), and the use of phytase enzymes to degrade phytic acid. Such approaches can help enhance the nutritional quality of phytate-rich foods without compromising their health benefits (Hurrell, 2003)[8].

Phytates represent a complex dietary component with both beneficial and potentially adverse effects. Their role in mineral chelation and bioavailability underscores the importance of considering dietary context and preparation methods. While high-phytate diets can pose challenges for mineral nutrition, the potential health benefits, including antioxidant properties, cancer prevention, and metabolic regulation, highlight the multifaceted nature of phytates in human health. Future research should continue to explore the nuanced interactions between phytates, nutrition, and health to develop optimized dietary recommendations.

References

1. Raboy, V. (2001). Seeds for a better future: “Low phytate” grains help to overcome malnutrition and pollution. Trends in Plant Science, 6(10), 458-462. https://www.sciencedirect.com/science/article/pii/S1360138501021047

2. Reddy, N. R., Sathe, S. K., & Salunkhe, D. K. (1982). Phytates in legumes and cereals. Advances in Food Research, 28, 1-92. https://www.sciencedirect.com/science/article/pii/S0065262808601639

3. Lonnerdal, B. (2000). Dietary factors influencing zinc absorption. The Journal of Nutrition, 130(5), 1378S-1383S. https://academic.oup.com/jn/article/130/5/1378S/4686088

4. Eladawy, T. A. (2002). Nutritional composition and antinutritional factors of chickpeas (Cicer arietinum L.) undergoing different cooking methods and germination. Plant Foods for Human Nutrition, 57, 83-97. https://link.springer.com/article/10.1023/A:1013189620526

5. Graf, E., Empson, K. L., & Eaton, J. W. (1987). Phytic acid. A natural antioxidant. The Journal of Biological Chemistry, 262(24), 11647-11650. https://www.jbc.org/article/S0021-9258(18)61347-3/fulltext

6. Vucenik, I., & Shamsuddin, A. M. (2003). Cancer inhibition by inositol hexaphosphate (IP6) and inositol: from laboratory to clinic. Journal of Nutrition, 133(11), 3778S-3784S. https://academic.oup.com/jn/article/133/11/3778S/4818020

7. Yoon, J. H., Thompson, L. U., & Jenkins, D. J. (1983). The effect of phytic acid on in vitro rate of starch digestibility and blood glucose response. The American Journal of Clinical Nutrition, 38(6), 835-842. https://academic.oup.com/ajcn/article-abstract/38/6/835/4691230

8. Hurrell, R. F. (2003). Influence of vegetable protein sources on trace element and mineral bioavailability. The Journal of Nutrition, 133(9), 2973S-2977S. https://academic.oup.com/jn/article/133/9/2973S/4688301