Skin is in. Whether you've been sunning yours on the beach this summer or just flaunting it at the endless round of pre and post-Fashion Week parties, you need to nourish it both from the inside out and from the outside in to keep it glowing. In a perfect world, we'd get all the nutrients our skin needs on our dinner plates. Real life makes that dream go for a toss. Not only do we need to ingest our multi vitamins, but now they want us to slather them on as well. Which is why, these days, there is a well-beaten path leading from the vitamin aisle to the beauty counter. So let's take a trip down that road, and relearn our ABCs...

Vitamin A
What it does inside your body:
A fat-soluble micro-nutrient, vitamin A is vital for healthy vision and cell reproduction. It also helps maintain skin, mucous membranes and the intestinal tract. It promotes wound healing, increases resistance to infections, treats acne and psoriasis, reduces PMS-related fluid retention and helps fight fatigue. Beta-carotene is the plant form of vitamin A and is commonly found in dark green, leafy vegetables, and orange and yellow coloured fruits and vegetables. (Ideal dose: 4000 IU daily for women and 5000 IU daily for men.)

Caution: Pregnant women should take their doctor's advice before starting this or any other supplement. Liver patients and women on oral contraceptives may be at risk for toxicity; so if you have any of the above conditions, make sure you get professional medical advice first.

What it does on the outside: Improves the look and feel of sun-damaged and ageing skin.

How it works: As we age, the production of collagen - the protein fibre that plumps skin from the inside out - tends to slow down. Exposure to the sun's ultraviolet rays can damage and degrade collagen too, making the skin look dry and wrinkled. Enter the retinoids! Synthetic derivatives of vitamin A and available in several cream applications, retinoids can help improve the skin's appearance by kick-starting the regeneration (and stopping the breakdown) of collagen, making it look firm and toned.