Transportation, long storage periods and modern processing methods strip foods of essential nutrients.
But while the average consumer can do very little to alter these factors, there are many measures one can take to counteract the nutrient losses. The key is to know what to buy and how to prepare it:
Buy as fresh as possible
To counteract nutrient losses due to storage and transport, try to buy greens that are as fresh as possible. The ideal is to source your fruit and vegetables from green grocers who buy from the market every day.
Another option is to support farmers' markets. At such markets, the produce is picked and brought directly to the market on the same day or within 24 hours, so it’s usually quite fresh.
Once you’ve bought the fresh produce, you also need to be careful how you store it at home. Keep fruit and vegetables in the fridge and eat them within one or two days.
Better cooking options
Use as little water as possible when cooking vegetables. This will prevent nutrients from being leached out into the water. Also use the water that vegetables have been cooked in for sauces or soups instead of just discarding it.
Steaming vegetables is an excellent option, particularly if you use very short cooking periods. Remember that the longer the foods are exposed to heat, oxygen and water, the greater the nutrient losses. Vegetables which are just cooked to the 'al dente' stage are crisp and crunchy and full of nutrients.
Don't store cooked foods for long periods in the oven or warming drawer. Cook and serve food as soon as possible.
Use microwave cooking at low power for short periods to retain more nutrients. Also use the microwave to re-heat foods. Research shows that this method retains more vitamins B1, B2, B6, folate and vitamin C than conventional reheating.
The role of frozen foods
If you have to choose between fresh and frozen, choose fresh. If you have to choose between canned and frozen, choose frozen.
In general, frozen foods retain adequate amounts of nutrients, provided they are frozen rapidly, stored in airtight packaging and thawed rapidly.
A few general rules for the use of frozen products:
Your freezer temperature should be -18oC or lower. Check the temperature and fix leaking rubber seals to save energy and maintain the required low temperature.
Only buy frozen foods that are solidly frozen, not half-thawed and soggy. Then rush home as quickly as possible and transfer the frozen products to your home freezer. In the South African summer, it’s a good idea to take a freezer box filled with ice packs along to the supermarket, so that you can store frozen products (and other perishables) in the freezer box till you get home. This will prevent thawing during the journey.
Check the instructions on the packaging. If the manufacturers advise that a frozen product shouldn’t be kept for longer than three months, stick to this time frame. Old packets of frozen food that lurk in your freezer should be discarded.
Don’t freeze meat for longer than three months. Not only does the meat lose significant amounts of B vitamins, but any fat on the meat may become rancid and affect the taste.
Buy unrefined grains
The nutrient losses caused by refining cereals and grains are astronomical.
Try to use unmilled and unrefined grains, cereals and flours. Buy unsifted maize meal, brown rice, crushed wheat, samp, and wholewheat pasta, and eat only wholewheat bread to guarantee the maximum vitamin B intake.
Buy unprocessed foods
Every step of the food-processing chain removes vital nutrients from food. Try to buy as few processed foods as possible.
If you can purchase your fruit, vegetables, meat and dairy fresh from the farm, you’ll ensure that you obtain the highest nutrient intake. If you live in a big city and this isn’t possible, hunt for sources of the freshest foods and eat foods raw or only slightly cooked.
Check expiry dates on processed foods, boil foods in the minimum amount of water for the shortest time possible, save the boiling water for stocks and soups, store frozen foods at the correct temperature, and make less use of convenience foods.
Variety is the key
The first and most important Food-Based Dietary Guideline for South Africans, developed by leading nutrition experts, states that we should eat a variety of foods.
By making sure that you eat a varied diet, you can counteract food nutrient losses. It's a case of “making up on the swings what you’ve lost on the roundabouts”.
Let's say one or two foods that you eat on a given day are low in nutrients. If you then eat another five to six other foods during that day, which may be richer in nutrients, this will balance out the losses.
Anyone who eats a monotonous diet by choice runs the risk of nutrient deficiencies. If you’re trying to lose weight and have decided to eat only a few foods to restrict your kilojoule intake, you run the risk of developing deficiencies.
A typical minimalistic slimming diet may consist of:
High-bran cereal for breakfast
Tuna and lettuce for lunch
A chicken breast with two veggies for supper
Slimmers often stick to this regimen day in and day out, exposing themselves to risks. Normally, they soon start to develop marginal vitamin and mineral deficiencies.
So, even if you’re trying to lose weight, you still need to eat a diet that is as varied as possible.
It’s evident that our modern food supply isn’t as rich in nutrients as it should be and that there are many factors that decrease the nutrient density of our diets. However, with careful purchasing, home storage, food preparation, and above all, by eating a varied diet, we can still ensure good health for ourselves and our families.
(Dr IV van Heerden, DietDoc, August 2007)
Any questions? Ask DietDoc
(Jane Ramberg & Bill H McAnalley (2002). From the farm to the kitchen table: A review of the nutrient losses in foods. Glycoscience & Nutrition, Vol 3, No 5, 1-12.)
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