A recent study showing more than permissible levels of heavy metals in vegetable samples taken from supermarkets and shops around Bengaluru has caused people considerable anxiety. It has ignited discussions on community Whatsapp groups and social media. Many media outlets and social media influencers have used this study to drive their fear-mongering agenda with headlines like “Avoid eating spinach sold in Bengaluru markets.”
Should we in a panic swear off vegetables altogether? Let us set the record straight by understanding how heavy metals contaminate vegetables and what we can do to reduce its impact.
First, traces of heavy metals in fresh produce is not a Bengaluru-specific problem. It’s just that a study on produce from Bengaluru supermarkets and stores was carried out recently and went viral on social media and made headlines all over. Similar studies are done from time to time in different places and usually yield similar results (Delhi, Solapur, Varanasi, Dehradun, and Patna to list a few).
Heavy Metals In Our Everyday Food
Heavy metals are naturally occurring elements found in the Earth's crust. While metals such as iron, copper and zinc are essential for our health in trace amounts, others, such as lead, cadmium, mercury, and arsenic can be harmful even in small quantities.
There are several ways in which heavy metals can find their way into our food. Natural contamination is the most common through which the vegetables, that have a natural affinity for certain metals, absorb them from the soil.
Environmental pollution like industry effluents, mining and usage of certain pesticides can also introduce heavy metals into plants. Plants irrigated with contaminated water (also untreated sewage water) is one of the leading causes of farm produce with high levels of heavy metals in and around Bengaluru and many parts of India. Food processing techniques and packaging materials are also some of the ways heavy metals leach into food.
Variation Across Vegetables
Vegetable species differ widely in their ability to take up and accumulate heavy metals, the highest being in leafy and the lowest in the gourd family. Different edible parts also have differing concentrations of heavy metals, leafy vegetables and root vegetables being the highest and legumes and gourds having the lowest.
Vegetables getting contaminated due to the quality of groundwater and water used in irrigation is a policy issue. Municipal corporations and other policymakers need to ensure farmers have access to clean treated water to irrigate their fields. Regular monitoring of the water source used for irrigation, ensuring there is no sewage water contamination into irrigation water and regular checks on heavy metal levels of the produce harvested are required to keep the levels under check.
How To Mitigate The Impact?
We all know policy changes don’t happen overnight. Meanwhile, should we stop consuming green leafy vegetables and other vegetables altogether? This is the food group with the single largest benefit to overall good health, so let us understand how we can reduce the impact of heavy metals and continue to enjoy its benefits.
Clean and wash the vegetables and leaves thoroughly. Soak in 2% salt solution (20g salt in 1 litre of water) for 5-10 minutes and rinse again.
Cook vegetables in water to dilute the concentration of the metals. Blanch green leafy vegetables before using them in cooking. Instead of making chutneys with raw greens, use quickly blanched greens or sauteed greens as in south Indian thogayals.
Eat more vitamin C and antioxidant-rich foods to counteract the potential negative effects of heavy metals.
Parents of young children should be especially cautious. Wash and cook vegetables and fruits in water thoroughly before pureeing them to make baby food to keep the concentration of heavy metals to a minimum. Given their small body weight, even a smaller dosage of heavy metals over a long period of time can have an impact on their health.
As leafy vegetables have more concentration of heavy metals in them in general as compared to other vegetables, avoid adding them to juices, smoothies or baby food. Wash thoroughly, blanch them and then use them for cooking.
Consider growing your own greens in pots on your window sill or balcony. This provides a steady supply of fresh, home-grown produce.
A point to note is that buying organic doesn't guarantee that the produce is free from heavy metals, as they can seep into vegetables from the irrigation water.
Finally, it's crucial to remember that the negative effects of not consuming vegetables far outweigh the potential risks of the 300-400 grams we eat daily. Armed with this knowledge, continue to enjoy your veggies while taking these precautionary measures.