Justin asks: My mum makes me take omega 3 and cod liver oil supplements, and blueberry extracts. I hate taking them - can't we get the benefits from real food?
Wynnie says: If you're eating a healthy, balanced and varied diet, you should be getting all the vitamins and minerals you need already.
Omega 3 fatty acids are naturally found in oily fish such as tuna, pilchards, mackerel, sardines and salmon, as well as in flaxseeds. These essential fatty acids cannot be manufactured by the body but are needed by the brain for cognitive (memory and performance) and behavioural functions.
Most people's diets tend to be low in essential fats which is why fish oil supplements have been such a hot topic over the past few years. Some preliminary studies in children found fish oil supplements contribute to an improvement in reading and spelling among children with attention deficit hyperactivity disorder. However, there isn't yet any strong evidence to suggest that fish oil supplements have a positive effect on the academic or behavioural performance of normally developed teens.
The disadvantages are that supplements are expensive, and omega 3 pills may be depleting our already threatened global fish stocks. The UK government doesn't recommend omega 3 supplements for all children and teens. Instead they suggest eating one portion of oily fish a week. And if you are taking cod liver oil tablets, these also supply omega 3 fats.
Blueberries are one of the most effective foods at destroying free radicals. The fruit itself is rich in antioxidants such as anthocyanins and pterostilbene. Preliminary research has shown that blueberry extracts may decrease the risk of some types of cancers, boost brain cells, promote eye health, maintain strong bones and help urinary tract function.
But as with all dietary supplements, just because a little is good doesn't mean more is better. Although there haven't been any reports of major side effects from taking blueberry supplements, there have been no clinical trials on humans unequivocally confirming the health effects of them, either.
It's likely that the beneficial compounds of any food, including blueberries and oily fish, work in synergy with other compounds in the 'whole' food. For example, there are 40 different types of anthocyanins in blueberries, plus hundreds of other compounds including fibre. An extract in a supplement just can't give you that combination.
Don't get lured into a false sense of security by loading up with supplements and then eating a poor diet of processed foods and no fruits and veggies. Eat yourself healthy by concentrating on whole foods and enjoying a healthy lifestyle.
Breakfast: macaroni with ham, cornflakes with warm milk, sausages and fried egg, toast with butter and honey or congee; tea or warm water
Lunch: noodles with fish balls, fast food from McDonald/KFC/Cafe de Coral or sandwiches; soft drink
Dinner: soup, steamed vegetables, chicken, beef, fish, pork, seafood dishes or curry, fruit
Snacks (at school): cuttlefish balls, chicken leg, potato chips, juice drinks
Snacks (after school): bread, sushi, pies or cakes; chocolate milk
Exercise: training every week for school cross-country, soccer and athletics teams.
Wynnie Chan is a British-trained nutritionist. If you've got a question for her or would like to be featured in this column, e-mail firstname.lastname@example.org