SINGAPORE - On April 6, a day before circuit breaker measures kicked in, vitamin C became one of the most sought after products in Singapore.

The supplement was the most-searched item online in early April, along with hand sanitisers and masks, according to South-east Asia meta-search website iPrice Group.

But consuming vitamin C alone is not enough, said Ms Bibi Chia, principal dietitian at Raffles Diabetes and Endocrine Centre.

"Another thing I recommend eating is vitamin D. People are staying home more and do not go under the sun as much as they used to, so your diet should give you enough vitamin D. It can be found in egg yolk and salmon fish. Alternatively, I rely on cod liver oil because it has natural quantities of vitamin A, D, and E."

With less physical activity, Ms Chia stressed the importance of portioning your food.

"If you look at a nine-inch plate, we are aiming for one-quarter carbohydrate, one-quarter lean protein, and the other half of the plate would be your vegetables."

For those who cook or bake at home, Ms Chia suggests switching to healthier ingredients such as whole grains and olive oil, and modifying the recipes.

"If the recipe calls for one cup of sugar, you might want to reduce it to three-quarter cups."

While fresh produce is an essential part of a balanced diet, frozen food has a longer shelf life, and is a convenient and cost-effective alternative.

"People have this myth that if it's frozen, it's not nutritious. But if you look at some vegetables and you compare its frozen nutrition as well as its fresh nutrition, they are actually similar if not higher. So you can consider some frozen fruit and vegetables in your freezer to make sure that you have fruit and vegetables in your diet," said Ms Chia.