Visiting Professor Patrick Holford of Teesside University sends out a newsletter to the paid-up members of his 100%health club with the assurance that his keen and expert sifting of health research means that he can share his wisdom and help the reader to “transform your diet, your health, your life!”. Regular readers will know that the newletter typically emphasises, as ever, the primacy of tests (rarely clinically validated) and supplements (ditto).
Newsletter 45 was no different except that it contains lengthy recommendations for genetic testing (very pricey). We may have more to say about the genetic testing at a later date but, for now, we would like to highlight a recurring theme in these newsletters: whoever writes them does not read research papers properly, misunderstands them or miscommunicates the findings. In addition, this benighted person sprinkles around errors in the generous manner of one practising the technique for dredging real Turkish Delight.
Pg. 5 of the issue 45, May 2008 is a Research Round-Up. So many assertions, so few references. Yet, despite this, the author displays a remarkable capacity to get the references wrong and to mis-report those papers that are cited more or less correctly. We can’t bear to cover each error so shall highlight some of them; the detail will be in the notes.
Lentils cut diabetes risk by 40%
Well, this would be worth knowing, eh? A heading like that, who wouldn’t want to learn more? Except, the reference is omitted and a later one substituted for it and some odd conclusions drawn.
Eating more foods from the legumes family, such as beans, pea and lentils, may protect your from Type 2 diabetes. A new study in the American Journal of Nutrition, which looked at over 64,000 women, found that eating these foods regularly was linked with a 40% reduction in the risk of Type 2 diabetes.1 Lentils in particular are great for diabetics as research has shown that eating a serving of lentils at one meal can halve the spike in blood sugar at the following meal.
The reference that is given in the quoted text is to Jenkins et al’s 1982 paper on lentils and second meal tolerance. Holford neglects to give any reference for the study which is the basis for the claim: Legume and soy food intake and the incidence of type 2 diabetes in the Shanghai Women’s Health Study. You can adjust for various factors such as education, age, smoking and exercise history all you like but you may have a sneaking feeling that the results of a population-based prospective cohort of middle-aged Chinese women in urban communities in Shanghai might not be readily generalisable to different population demographics and that it might have been helpful if the research summary had mentioned that.[a]
I originally had an extensive digression here about Holford failing to comment on the authors’ use of odds ratios and the Cox proportional hazards model. But, on reflection and while writing my 19th explanatory note, I experienced a niggling sense that it might not be appropriate. The stats wonkery might surface at another time but not today. However, that 40% reduction is not all that it might seem and the natural frequency is not likely to be that impressive. From a baseline of no participants with diabetes type II, and a follow-up of av. 4.6 years, the researchers report that there were 896 confirmed cases although there were 1608 reported cases (the researchers used the latter figure in their analyses). 1608 is approx 2.5% of 64,227; 896 is approx 1.4%. You can look at the distribution of these in the tables such as Associations between the incidence of type 2 diabetes mellitus and consumption of legumes and soy food.
And what about the Jenkins et al study that prompts the assertion that lentils “are great for diabetics”. The study was published in 1982 and involved 7 healthy volunteers: a lot of research has been done since then, work on the glycaemic index and load and the colonic fermentation of indigestible fibre. It must be possible to find a better reference to support this point if it is an appropriate one and to mention that it is not just lentils, as distinct from other members of the legume family, that might be highlighted as helpful for some diabetics.
So, all in all, that headline “Lentils cut diabetes risk by 40%” – it is a little more complicated than that.
Soya stops breast lumps – and builds bones
Would you be startled to learn that this is another paper about the same study of women in Shanghai? And that Holford (or whomever) seems to be confusing correlation and causation?
A recent study has found that women with a high intake of soya not only had reduced breast cancer risk but also had less [sic] cases of fibrocystic (ie lumpy) breast conditions. In addition, women can also benefit from the positive effects soya has on bones – an intake of 90mg or more of soya isoflavones each day can increase bone mineral density. This is especially important for post-menopausal women who are at increased risk of osteoporosis.
Blech, again, I would mention that discussions of the need for genetic testing for the Worried Well take up a ridiculous amount of this newsletter but here was a valuable teaching moment for understanding phenotypes and other factors[b] yet we may as well loop Depeche Mode’s Enjoy The Silence with Simon and Garfunkel’s Sound of Silence. I should also add that it would be an opportunity for Holford to discuss intestinal bacteria that metabolise particular soy isoflavones. But I definitely don’t want to discuss those although Holford normally can’t refrain from mentioning gut flora yet is uncharacteristically silent on this point (it’s one thing to pontificate about gut flora and the need for probiotics, it’s another to discuss specific bacteria and their actions and acknowledge that you don’t have a product for this – yet).
Anyway, even readers who are restricted to the abstract might notice that:
Women in the highest quartile of plasma genistein (>76.95 ng/mL) were less likely to have breast cancer (odds ratio, 0.26; 95% confidence interval, 0.13-0.50) or benign conditions (odds ratio, 0.40; 95% confidence interval, 0.23-0.70) compared with women in the lowest quartile (<9.42 ng/mL).
Note b[b] might offer some insight into why the findings relate to genistein although the researchers looked at “possible relationships between plasma genistein and daidzein concentrations and risk of breast disease in women”. Again, readers might wonder whether the interesting results from this study are readily generalisable to other demographics.
We can’t comment on the bone mineral density, and claims for osteoporosis because we haven’t seen the full text of the meta-analysis of randomised controlled trials that involved 10 studies and a total of 608 participants. However, a very recent double-blind placebo-controlled RCT involving 237 women yielded a different result, specifically for a particular demographic of white women:
Consumption of foods containing 110 mg/d of soy isoflavone aglycone equivalents for 1 y did not prevent postmenopausal bone loss and did not affect bone turnover in apparently healthy early postmenopausal white women.
However, we can not make a fully informed comment because we can’t, as yet, check the method for including trials in the meta-analysis that Holford cites. Holford makes a recommendation that women should consume soya, lentils or other source of isoflavones every day. Which is as maybe but is a rather piecemeal approach; there are several other dietary recommendations that may be relevant and consider your diet as a whole rather than a series of isolated elements. We would also make a plea for ensuring adequate vitamin D through safe exposure to sunlight on a regular basis or from dietary sources and for regular, weight-bearing exercise.
Chromium improves concentration
Such a gift but the most obvious gags are not always worth doing. Holford not only repeats his usual riff about the blood sugar balancing properties of chromium but gets to claim:
new research shows that chromium also improves brain function and concentration. A study in Italy found that supplementing with 1000mcg chromium picolinate per day improved brain function in older adults with memory decline.
Well, that would startle most people who would expect to be told about statistically significant results. The source for this finding is a press release about a study that looked at the impact of a commercial product, specifically Nutrition 21’s Core4Life Advanced Memory Formula: apparently, the results were presented at a ‘neurological meeting’. Despite the fact that there were only 21 participants, it was a randomised, double-blind, placebo-controlled study conducted over 12 weeks: the adults were 65 years and older with early memory decline. The qualifier early may or may not be important. And the results, the ones that should have you leaping to push chromium supplements on your older relatives?
Those receiving the chromium picolinate supplement showed a trend for reduced interference from irrelevant words on the memory task (p = 0.12). In addition, on another task assessing fine motor control and speed, the subjects receiving chromium picolinate exhibited enhanced motor speed relative to those receiving placebo (p = 0.16). [My emphasis.]
Read it and weep, eh? Possibly, in an eerie example of the persuasive capacity of brain images and neuroscienciness (as summarised by Dr Ben Goldacre in an item about why Brain Gym circumvents the critical faculties of so many people), Holford was dazzled by the references to fMRI and the images with bright colours.
You might also have noticed that the product contains:
Nutrition 21’s proprietary chromium picolinate found in Core4Life™ Advanced Memory Formula™, a nutritional supplement specifically formulated to improve brain health. Core4Life Advanced Memory Formula contains a unique combination of chromium picolinate, phosphatidylserine (PS) and DHA.
So, even if this study were better than it seems, it is not just chromium picolinate, no matter how much Holford wants to use it to piggy-back sales of his own recommendations.
There was more research, just as ineptly mis-reported but we shall spare you the remainder.
[a] The authors provide a good overview of various confounding variables. However, it is implausible that Holford’s general reader will be aware of anthropometric differences between (say) white european women and chinese women.
A higher intake of total legumes was associated with higher exercise participation, higher educational level, and not having ever smoked. Participant characteristics with regard to intake of soybeans or other legumes were similar to those of total legumes. A higher total soy protein intake was associated with older age, higher exercise participation, higher alcohol consumption, and the presence of hypertension at baseline. The median intake for total legumes was 30.5 g/d, for soybeans was 11.0 g/d, for peanuts was 0.7 g/d, and for other legumes was 15.5 g/d…
The findings of this study contribute to a literature in which the association of the frequency of legume consumption and diabetes type II is rather conflicting and varies considerably, both with country and overall diet. The summary of the findings is:
The multivariate-adjusted relative risk of type 2 DM for the upper quintile compared with the lower quintile was 0.62 (95% CI: 0.51, 0.74) for total legumes and 0.53 (95% CI: 0.45, 0.62) for soybeans. The association between soy products (other than soy milk) and soy protein consumption (protein derived from soy beans and their products) with type 2 DM was not significant.
It is difficult to equate that to “lentils cut diabetes risk 40%”.
[b] It is off-topic for this post but it looks as if different responses to soy isoflavones (genistein and daidzein) may reflect phenotypes. It is increasingly looking as if the beneficial health effects may be associated with daidzein-metabolizing phenotypes in conjunction with several other influences and factors. There are indications, that need to be confirmed, that the relevant phenotypes may vary with race and ethnicity: see, e.g., Prevalence of daidzein-metabolizing phenotypes differs between Caucasian and Korean American women and girls and Demographic, anthropometric, and lifestyle factors and dietary intakes in relation to daidzein-metabolizing phenotypes among premenopausal women in the United States.
 Jenkins DJ, Wolever TM, Taylor RH, Griffiths C, Krzeminska K, Lawrie JA, Bennett CM, Goff DV, Sarson DL, Bloom SR. Slow release dietary carbohydrate improves second meal tolerance.
Am J Clin Nutr. 1982 Jun;35(6):1339-46.
 Villegas R, Gao YT, Yang G, Li HL, Elasy TA, Zheng W, Shu XO. Legume and soy food intake and the incidence of type 2 diabetes in the Shanghai Women’s Health Study. Am J Clin Nutr. 2008 Jan;87(1):162-7.
 Lampe JW, Nishino Y, Ray RM, Wu C, Li W, Lin MG, Gao DL, Hu Y, Shannon J, Stalsberg H, Porter PL, Frankenfeld CL, Wähälä K, Thomas DB. Plasma isoflavones and fibrocystic breast conditions and breast cancer among women in Shanghai, China. Cancer Epidemiol Biomarkers Prev. 2007;16(12):2579-86.
 Ma DF, Qin LQ, Wang PY, Katoh R. Soy isoflavone intake increases bone mineral density in the spine of menopausal women: meta-analysis of randomized controlled trials. Clin Nutr. 2008 Feb;27(1):57-64.
 Brink E, Coxam V, Robins S, Wahala K, Cassidy A, Branca F; PHYTOS Investigators. Long-term consumption of isoflavone-enriched foods does not affect bone mineral density, bone metabolism, or hormonal status in early postmenopausal women: a randomized, double-blind, placebo controlled study.
 New clinical data shows chromium picolinate improves cognitive function.