Updated: Nov 26, 2021
For humans, food is an artefact. We are the only species that goes further than eating what we find straight from nature’s bounty to producing it ourselves through agriculture and transforming it through cooking and processing. We creatively blend, cure, ferment and preserve to infuse flavour, elevate taste, change textures, and produce new shapes.
One of the primary physiological objectives of eating is to absorb as many nutrients as possible. Historically, when cooking with fire emerged, it enabled us to absorb more nutrients from tubers, grains, legumes and meat, and destroyed most pathogens in food. Humans then evolved to have smaller gastrointestinal tracts and bigger brains than our primate ancestors. It freed the hours spent on eating and digestion, and allowed our predecessors to engage in creative endeavours and rest.
Cooking is also a science that creates unique and innovative recipes to nourish the body and affect its functioning. However, it has mixed effects on nutrients.
The choice to cook or not to cook your food is guided by nutrient retention, ease of digestion, absorption and the eventual impact on the body’s ability to operate.
As a Functional and Integrative Nutritionist, I select ingredients based on their characteristics, and alter recipes to improve their nutritional value.
Best Cooked... Tomatoes are high in lycopene, a red pigment known to prevent some cancers and improve heart and eye health. To extract maximum goodness from this blushing sweet and sour staple, cook and eat with a healthy fat source. Carrots are a rich source of many carotenoids, which are precursors of vitamin A (meaning that the body converts them into vitamin A). Beta carotene is an antioxidant that supports eye health, growth, and immunity. It is better absorbed when carrots are cooked and eaten with a source of fat. For a warming meal on a cold winter’s eve, make a carrot, coriander and peanut butter soup.
The cancer-fighting ferulic acid in asparagus is more absorbable when cooked. So, next time lightly grill your asparagus with olive oil, garlic, and a squeeze of lemon juice. Gently cooking spinach for two to five minutes increases the absorption of beta-carotene and iron. Cruciferous vegetables such as kale, cabbage and broccoli are also a rich source of carotenoids. Cabbage, especially the red type, needs a gentle steam or boil to release more carotenoids.
Steaming broccoli preserves up to three times more vitamin C than boiling it. Also, when boiled, it loses its naturally sweet flavour, and the nutrients seep into the water. Tocopherols (which have vitamin E activity) and carotenoids (lutein and beta carotene) increase with cooking. On the other hand, heat damages the enzyme myrosinase, which makes anti- cancer compounds glucosinolates.
The trendy kale, like all cruciferous vegetables, has many essential nutrients, including vitamins, minerals and antioxidants. Yet, it is also a source of goitrogens. People with hypothyroidism should avoid eating it in excess in a raw state, as it may suppress thyroid activity and increase the risk of goitre. To deactivate the enzyme that causes the goitre effect, lightly cook your cruciferous vegetables.
Cruciferous vegetables are high in sulphur, which may reduce the risk of cancer. If they give you tummy discomfort, slowly ease into them, and boil them for two to five minutes. Most vegetables, especially the leaves and green types, are fragile. So cook them slowly, at low heat, whilst maintaining the crunchy texture and fragrant flavours. A quick two to five minutes will do - the intention is to maximise nutrients, not to kill them.
Best Raw... Heating garlic reduces the allicin, which promotes cardiovascular health, for example by lowering blood pressure and cholesterol. Use it in raw salads, in dressings, or even added raw to roasted winter vegetables. Eating onions raw preserves more antioxidant flavonoids and cancer-fighting sulfur compounds. Add a few slices to your salad or lunch sandwich. Cooking red peppers damages their vitamin C - one of the most unstable of all the vitamins. As with broccoli, heat damages the important enzyme myrosinase in watercress. Remember, we don’t only eat for nutrition. Food is a rich component of culture, human interaction, and sensory pleasure. So use these guidelines as a map on your journey to nutritional wellbeing, but be sure to enjoy a variety of raw and cooked foods to enrich your dietary experience.