Nutrition 4 you
Name: Derek Feng
Breakfast: Milkshake made with bananas, milk, apples, walnuts, other nuts and Wolfberry; lemon and honey water
Snack: Green apple, grapes or cherry tomatoes; yoghurt-coated muesli bar, seaweed or bread
Lunch at school: Rice box, usually chicken and corn, beef and vegetables or pork fried rice
Lunch at home: Boiled frozen dumplings
Snack: Orange juice
Dinner: Chinese-style meal usually steamed fish or salmon, boiled eggplant with home-made sauce with lemon and vinegar, egg and tomatoes
Eating out: California Pizza Kitchen with friends; Chilli N' Spice with family, for some exotic flavours
Favourite foods: 'I love mangosteen - the most underrated fruit.'
Hates: Dried scallops
Lifestyle: Plays three hours of badminton, two hours of soccer, an hour of table tennis and a couple of hours of tennis each week
Derek asks 'I love to eat the lemon slices that often garnish dishes. How much lemon is too much? And what will happen if I eat too much?'
Wynnie says: Lemons are rich in vitamin C. In the mid-19th century they were prized and sought after fruit, as they were used to prevent scurvy - a disease which typically affected seafarers without access to citrus rich fruits.
Scurvy is a caused by a severe deficiency of vitamin C and results in the loss of teeth, excessive bleeding, swollen gums and and wounds failing to heal properly.
Lemons have other important health benefits. They contain compounds called limonoids which may help fight cancers of the mouth, skin, lungs and stomach.
A recent study has shown that limonoids remain active for up to 24 hours in the body, which may explain why it can prevent cancer cells from growing and spreading.
On the downside, lemon juice is extremely acidic and can cause irreparable erosion of the tooth enamel.
If you drink undiluted lemon juice, it's important to follow it with a glass of water, and to brush your teeth as soon after as you can. This will help buffer the acidic effects.
Chewing or sucking lemon slices is much more harmful to your teeth than drinking lemon juice, because enamel erosion is related to the the length of time the acid has contact with your teeth.
Derek's snack tips
Dark chocolate is a healthy substitute to regular chocolate - and it tastes just as good.
Natural yoghurt mixed with blueberries and dried cranberries is another wonderful snack I often eat.