First off, a humble apology for the lack of updates. I've been tied up with thesis corrections and then graduation (embarrassing pictures of me dressed as a cross between Henry VIII and Superman via Hogwarts are floating around somewhere. Hopefully I'll be back to posting regularly again now. So here is my guide to nutritional supplements which may actually do you some good!
You can't move nowadays for adverts for nutritional supplements, telling you to buy this product so that you can enhance your life/training/fat loss/libido/pattern baldness. While many of these claims are spurious at best, and not supported by much, if anything, resembling proper scientific research, some of these supplements are worth adding to your diet. While of course the bulk of your nutritional intake should come from real food which has been processed as little as possible (meat & fish, vegetables, fruit, nuts), there is much to gain from adding a few extras to help boost your intake of quality nutrients. Here are a few which I consider to be advantageous, and supported by real scientific evidence. I should add that I take all of these and have found them to be beneficial, but have no commercial interest in any of the products suggested here.
Of course it can, Dr. Oz.
Multivitamins/minerals: As I said
above, the bulk of your nutrient intake should come from real food, since the
nutrients are found in their most bioavailable form. But here are 2 reasons for
topping up on micronutrients. Firstly, it seems that the nutritional quality of
our food has declined 1,2, so you might not be getting quite what you think from your fruit
and veg. Secondly, the RDAs (Government Recommended Daily Amounts) for vitamins
and minerals are the amounts suggested are the amounts which will prevent deficiency
disease. Yes, the 60mg of vitamin C the government says you should have every
day is enough to prevent you getting scurvy. Hardly optimal nutrition is it? So
bumping up your levels of vital minerals and vitamins through supplements
suddenly seems like a good dies for anyone who wants more out of life than
simply avoiding disease. Another highly-publicised reason for eating a diet
high in plant-derived vitamins and minerals is the Five-A-Day campaign, which
suggests that you can reduce your risk of disease, in particular some cancers,
by consuming your five portions each day. What they don't tell you is that when
formulating this campaign the evidence pointed to the fact that you needed TEN
portions a day to reduce these risks, but it was thought that this would put
the public off, so it was halved (in Western Australia it's a more honest - and
incidentally successful - 7-a-day 3). In this case your laudable commitment to a diet high in fruit
and veg might not be enough to give you the results you think you're getting.
So why not give yourself that boost by topping up with a quality vitamin and
mineral supplement? 
Fish oil: this is a supplement which receives plenty of publicity, being praised
for its ability to seemingly improve almost everything. It is also quite a
tricky one to explain the benefits without getting quite technical, but I'll
give it a go. Normal chemical and immunological reactions in the body can
produce compounds which are inflammatory, i.e. they can cause damage to cells.
Usually the body can cope with this inflammation up to a point via the immune
system, but in certain conditions such as arthritis, this inflammation goes
unchecked and causes damage to tissues, causing pain. Fish oil appears to have
an effect on the production of inflammatory compounds by altering the metabolic
pathways so that fewer inflammatory compounds are produced. What this means in
practice is that fish oil can enhance your recovery from exercise (training
increases the number of reactions in the body, potentially increasing the
amount of inflammatory compounds produced), as well as enhancing immune
function and reducing the risk or severity of inflammatory conditions, such as
arthritis, atherosclerosis, and some forms of cancer. Since most people
struggle to eat oily
fish on a regular basis, a quality supplement such as PurePharma seems like
a good idea. 
Magnesium: modern life is full of stress, and poor quality sleep is both a
cause and an effect of this. Magnesium deficiency has been associated with poor
quality sleep4, possibly due to its functions in regulating muscle contraction
and nerve function5. Studies have demonstrated that Magnesium supplementation can
improve both quality and duration of sleep. I suggest that you go for Magnesium
Citrate (available at Holland and Barrett), since it is better absorbed than
the more commonly-available Oxide form 6. Take 500mg before bed, but start with a lower dose and ramp it
up gradually. A sudden increase in your intake could cause nasty
gastrointestinal side effects, and you don't want those. 
Probiotics: I
have already written at length on these, what with
their being the subject of my
PhD, so I won't bore you with the minutiae again. A brief list of their
advantages includes better digestion of
nutrients, reduced cholesterol,
prevention of gastrointestinal and urinary tract infections, reduced risk of
inflammatory bowel conditions and reduced duration of colds. There is plenty of
evidence to support this (trust me, I've just spent 4 yes looking at it!), so
these are well worth adding to your nutritional plan.
So there you have my recommendations for supplementation. This is
by no means an exhaustive list, and is not targeted at any specific population.
This is a list of supplements which are safe, have a good amount of scientific
evidence attached to their efficacy, and whose intake would benefit just about
anyone. If you want me to discuss any specific supplements, or supplementing
for a specific group, please leave a comment here, or email me at cmcnutrition@gmail.com
References
1 Mayer, A.-M. Historical changes in the
mineral content of fruits and vegetables. British
Food Journal 99, 207-211 (1997).
2 Davis, D. R., Epp, M. D. &
Riordan, H. D. Changes in USDA food composition data for 43 garden crops, 1950
to 1999. J Am Coll Nutr 23, 669-682, doi:23/6/669 [pii] (2004).
3 Pollard, C. M. et al. Increasing fruit and vegetable consumption: success of the
Western Australian Go for 2&5 campaign. Public
Health Nutr 11, 314-320,
doi:S1368980007000523 [pii] 10.1017/S1368980007000523 (2008).
4 Nielsen, F. H., Johnson, L. K. &
Zeng, H. Magnesium supplementation improves indicators of low magnesium status
and inflammatory stress in adults older than 51 years with poor quality sleep. Magnes Res 23, 158-168, doi:mrh.2010.0220 [pii] 10.1684/mrh.2010.0220 (2010).
5 Eby, G. A. & Eby, K. L. Rapid
recovery from major depression using magnesium treatment. Med Hypotheses 67,
362-370, doi:S0306-9877(06)00103-4 [pii] 10.1016/j.mehy.2006.01.047 (2006).
6 Walker, A. F., Marakis, G., Christie,
S. & Byng, M. Mg citrate found more bioavailable than other Mg preparations
in a randomised, double-blind study. Magnes
Res 16, 183-191 (2003).
