You may be interested in Holford’s opinion on the matter of natural v. synthetic vitamins in his 1985 classic, Vitamin Vitality: pp. 122-3 (quotations between rules to make them easier to read).
Natural versus synthetic
A great deal of rubbish has been said and written about the advantages of natural vitamins. First of all, many products claiming to be natural simply aren’t. By law, a certain percentage of a products must be natural for the product to be declared ‘natural’. The percentage varies from country to country. By careful wording some supplements sound natural but really aren’t. For instance, ‘vitamin C with rosehips’ invariably means synthetic vitamin C with added rosehips, although it is often confused with vitamin C from rosehips. So which is better?
By definition, a synthetic vitamin must contain all the properties of the vitamin found in nature. If it doesn’t then the chemists haven’t done their job properly…
However, synthetic vitamin C (ascorbic acid) has the same biological potency as the natural substance, according to Dr Linus Pauling,  although chromatography and Kirlian photograph have shown visible differences between the two. No one has yet shown that natural vitamin C is more potent or beneficial to take. Indeed, most vitamin C is synthesized by taking a ‘natural’ sugar, such as dextrose; two chemical reactions later you have ascorbic acid. This is little different from the chemical reactions that take place in animals that convert sugar to vitamin C. Vitamin C derived from, say, acerola cherries – the most concentrated source – is also considerably bulkier and more expensive. Acerola is only 20 per cent vitamin C, so a 1,000mg table would be fives times as large as a normal tablet and would cost you ten times as much! 
It is true that vitamins derived from natural sources may contain an unknown element that increases their potency…Vitamin C is found in nature together with the bioflavanoids, active nutrients that appear to increase the potency of vitamin C, particularly in its capacity of strengthening the capillaires or tiny blood vessels. The best source of bioflavanoids is citrus fruit, so the addition of citrus bioflavanoids to vitamin C tablets is one step closer to nature.
1 L Pauling, Vitamin C and the common cold. Pg 27 (Berkley) 1981.
2 J Kinderlehrer, Natural versus Synthetic. Reprinted in Prevention Magazine. [No date given, which is presumably what the n.d. in Holford’s reference indicates.]
3 M. Colgan Your Personal Vitamin Profile. Pg. 140 (Blond and Briggs) 1983.
Oddly enough, the widespread belief in the virtue of supplements is mostly grounded in Orthomolecular Medicine and it is interesting to see the earlier Holford aligning himself with Linus Pauling and Dr Andrew Saul in opposing the criticism of synthetic vitamins. According to Pauling in Vitamin C and the Common Cold (all following Pauling quotations are from the 1970 edition):
There is only one vitamin C. It is the substance L-ascorbic acid, which is also called ascorbic acid…So-called synthetic ascorbic acid is natural ascorbic acid, identical with the vitamin C in oranges and other foods. [Vitamin C products that are derived from rose hip extracts or similar have] no advantage whatever…In fact, there is a disadvantage that you would waste your money if you bought them, rather than the ordinary ascorbic acid. [Pauling, L. (1970) Vitamin C and the Common Cold, San Francisco: W. H. Freeman and Company. pg. 89]
On pg. 90, Pauling advises the reader that at the then current prices, vitamin C should cost around $5-7.50/kg. He warned readers not to buy ascorbic acid if it cost more than $20 per kilogram.
The dealer also misleads his customers by suggesting that ordinary ascorbic acid is different from ‘all-natural vitamin C, from organically grown rosehips imported from Northern Europe.’ The words ‘organically grown’ are essentially meaningless — just part of the jargon used by health-food promoters in making their excess profits, often from elderly people with low incomes. [pg. 91]
Pauling continues in this vein and on pg. 95 he suggests that appropriate supplementation with cheap (generic) multivitamin supplements should only cost a few dollars a year. Interestingly, on pages 96-7 Pauling discusses ‘bioflavinoids’ (both he and Saul use this term) and declares that they are likely to have little or no role in the prevention of the common cold and therefore “need not be included in the regimen”.
Dr Saul makes several similar points in: What’s the difference between natural and synthetic vitamins?
Most vitamin products, even those sold in health food stores or by distributors, contain synthetic vitamin powders. There are only a few manufacturers of vitamin powders, and they are almost always large pharmaceutical companies. Generally,
a) Laboratory-made vitamins are far cheaper than whole food concentrates;
b) Synthetic vitamins USUALLY work quite well,
c) High potency can be achieved with a nice, small tablet size
Drs. Linus Pauling, Ewan Cameron, Robert Cathcart and others have established that very high doses of factory-made ascorbic acid vitamin C work just fine against viral and bacterial illness.
Saul recounts an anecdote about Dr Szent-Gyorgyi (family friend and mentor of Dr Aust, alongside the Pauling family) and some lab animals that surreptiously ate his dinner of stuffed pepper (rich in bioflavinoids) and subsequently absorbed more vitamin C. Saul concludes we should obtain phyto-nutrients from food and not shoe-horn them into supplemental vitamins which should be cheap.
I (in agreement with Linus Pauling) recommend that people buy the cheapest vitamin C they can find, and take a lot of it…
I recommend that people take cheap C, AND eat right. Foods are a lousy source of vitamin C but an excellent source of bioflavinoids. Vitamin C tablets are a lousy source of bioflavinoids, but a good source of C. Good match.
Overall, it seems the pillars of orthomolecular medicine support the value and cost-effectiveness of synthetic vitamins. They argue that for some of them, even if people absorb less (not an established fact in every case but see Natural versus synthetic vitamins), then this is an argument for advising a larger dose of an affordable substance to supplement a wholesome diet.
So, it may seem a little puzzling that the Biocare Vitamin C and Patrick Holford range both stress the inclusion of extracts of fruit and similar substances as sources of bioflavonoids. All of this does seem to increase the price of the supplements substantially. One feels that Linus Pauling would be very disappointed.