As well as consuming the foods mentioned, I take extra doses of this important immune-building vitamin for a few days. Vitamin A is a fat-soluble vitamin so, like other fat-soluble vitamins, you can take too much of it (the exception to this is Beta-Carotene as there are no known toxicity levels.... well, other than your skin turning orange. Really.). Its perfectly fine for a short time, such as a week or so, to take extra and so I take 1 or 2 pills (10,000 IU's) with breakfast and sometimes dinner as well (always take fat-soluble vitamins with food as to help your body absorb them better). I do this for a couple of days and then decrease to 1 or 2 pills/day for the rest of the week.
Most everyone knows about Vitamin C and you can take this with or without food (water-soluble vitamin, if you take too much you'll pee it out). I recommend taking Vitamin C complex (ascorbic acid is just one part of the complex) and make sure it includes Bioflavanoids to get the most out of it. I usually take between 1,000-2,000 mg of this while I'm sick. And I can't forget garlic - increase your intake of nature's antibiotic (anti-fungal, anti-viral as well) whether cooked, raw or in pill form.
A few other important points - decrease your dairy intake as well as orange juice. While orange juice contains Vitamin C it, as well as all dairy, can be mucus-causing which is something you don't want more of when you have a cold. Magnesium (which I've talked about in a previous blog) is also an important mineral for our immune system, as is drinking lots of pure water (herbal teas are fine as well), getting enough sleep and making sure you eat on time. Avoid all processed sugar (and white flours) as sugar will demobilize our white blood cells (think fighter cells) for approximately 30 minutes after consumption. We need to arm our bodies with the weapons (quite literally) that it needs to keep those germs at bay!