Participants were asked what supplements they had taken in the past 30 days and submitted the product label to National Center for Health Statistics nutritionists.
Google Analytics, a free product that allows online publishers to gather statistics about visitors to their sites, was used on 81 of the top 100 sites.
The Office for National Statistics said that gross domestic product (GDP) grew 1.0% in the three months from July to September, having contracted in the previous three quarters.
India's statistics ministry estimated Thursday that gross domestic product would grow 5% in the year ending March 31, weaker than the previous year's growth of 6.2% and sharply down from the 9%-plus growth rate recorded in early 2011.
The Office for National Statistics revised the decline in gross domestic product in the first three months of this year to 0.3 percent, up from the 0.2 percent it estimated last month, because of a deeper slump in the construction industry.