Whole Grains and Organic VegetablesJune 22, 2009 Written by JP [Font too small?]
Lots of people become frustrated when trying to interpret nutritional information. One day the news will report that eggs are dangerous and should be eaten only on rare occasions. A few months later, the headline will read that eggs can actually promote good health when eaten daily. This same type of back and forth can be found in most aspects of diet and lifestyle modification. The way to deal with conflicting data is either examine them closely or seek out those who make it their business to do the detective work for you. By following either of these tactics, the mystery surrounding the debate about what’s healthy and what’s not becomes much more manageable and, in turn, will make you a nutritional insider.
Today I’ll take a look at two stories that are currently in the news. They both challenge certain assumptions many people have about how specific foods impact wellness. I hope that the way that I approach these issues will illustrate one possible model for interpreting nutritional studies in general.
A trial published in the June 16th issue of the Nutrition Journal makes a rather shocking claim: Whole grain bread is no better than processed “white bread” in terms of promoting healthy blood sugar levels. This goes against the modern wisdom promoted by most conventional and many naturopathic doctors and nutritionists. Generally speaking, the view is that the higher levels of fiber, nutrients and phytochemicals found in whole grains help promote more stable blood sugar levels. Larger quantities of these substances are also widely believed to support cardiovascular, digestive health and good health in general.
In this study, ten healthy volunteers ate 150 grams of “white wheat bread” or “whole-meal rye bread” on different days. Blood sugar levels and “gastic emptying” (the rate by which the respective breads were processed in the digestive system) was measured first thing in the morning and after an overnight fasting period. Blood tests monitored glucose variations before and after each challenge, and the gastric emptying rate (GER) was determined by the use of a form of ultrasound technology. (1)
The composition of the rye and white breads was as follows:
- The white bread contained 0 grams of dietary fiber and fat, 13.5 grams of protein, 52 grams of carbohydrates and a total of 435 calories per 150g serving.
- The whole grain rye bread contained 3.75 grams of dietary fiber and 4.5 grams of fat, 12.75 grams of protein, 62.7 grams of carbohydrates and a total of 390 calories per 150g serving.
The surprise that the researchers uncovered is that “no statistically significant difference was found between the GER values or the blood glucose levels following the two meals”. They went on to comment that, “Our hypothesis was that dietary fibre would lower the postprandial blood glucose response, in comparison with the reference meal, due to delayed gastric emptying. We were not able to verify this hypothesis.”
I’m really not a big fan of bread or flour-based products in general, even if they’re made of whole grains. I think they can often promote an unhealthy rise in blood sugar and appear to carry a rather significant risk of allergic reactions and digestive complications. (2,3,4,5,6) Having said that, I’m not prepared to accept the current proposal that more heavily processed grains are equivalent to whole grains which are left relatively intact. There’s simply too much evidence to suggest otherwise. In fact, a study released in the May edition of the European Journal of Nutrition demonstrated that rye bran helped to manage post-meal blood sugar better than oats (which contains less fiber). (7)
I am, however, thrilled to find a study like this because it affords us all an opportunity to perform a similar test on ourselves. If you regularly consume whole grain foods, test your blood sugar to make sure that they’re having the desired effect on you. Don’t just assume that they’re doing well for you just because that’s the current dogma. You may be surprised by what you find. If the results of your personal testing come back with your expected conclusion, then you know that you can safely disregard this most recent study. If not, then this is your chance to make a dietary change for the better.
Another recent study in the British Journal of Nutrition determined that there wasn’t a statistically significant difference in antioxidant levels in organically grown and conventionally grown carrots. In addition, the same researchers tested to see if the consumption of blanched organic or conventional carrots (200 grams per day for 2 weeks) would enhance antioxidant quantities or immune function in a group of 36 male volunteers. To the shock of many, the scientists determined that neither form of carrot significantly increased the levels of antioxidants, protected against DNA damage or demonstrably improved immunity. (8)
But by looking closely at the details of the research, I found that there were slightly higher levels of antioxidants present in the organic vs the conventional carrots:
- Carotenoid Levels: 121μg/g organic vs. 116 μg/g conventional
- Antioxidant Capacity: .43 umol organic vs. .32 umol conventional – Trolox equivalent.
The absence of significant antioxidant changes within the volunteers may have something to do with the well established need for simultaneous fat consumption for optimum absorption of carotenoids – a key group of antioxidant pigments in carrots and other fruits and vegetables. In fact, a study from a few years back determined that, “esssentially no absorption of carotenoids was observed when salads with fat-free salad dressing were consumed. A substantially greater absorption of carotenoids was observed when salads were consumed with full-fat than with reduced-fat salad dressing.” (9,10,11)
Speaking of carrots, if you really want to get the most out of them, take the advice given by scientists at Newcastle University. Cook your carrots whole before cutting them. If you cut your carrots prior to boiling them, not only won’t they taste as good, but you’ll lose about 25% of their antioxidant properties. The taste claim was evidenced by a “blind taste test” conducted in almost 100 people using whole boiled carrots or cut boiled carrots. 80% of the participants preferred the taste of the whole boiled variety better. (12)
This is yet another example of the advantage of getting inside an experiment to ferret out the details. By doing so, you can accurately assess whether or not buying organic carrots is worthwhile for you. You’ll also have a better basis for determining how and whether you want to incorporate carrots in your diet. The answers to such questions aren’t always as straightforward as the media presents them. But by embracing the complexity for these health subjects, you can more fully benefit from what the science is really trying to tell us.
Tags: Carotenoids, Organic, Whole Grains
Posted in Diabetes, Food and Drink, Nutrition
June 23rd, 2009 at 8:00 pm
I’m a diagnosed type 2 diabetic and rely heavily on whole grains, but eat no flour products. Two of my daily meals consist of boiled whole grain kernels, usually oats and barley. Oats is high in protein and barley is high in fiber. My last A1C was 5.1
Cut neither the carrots nor the grain.
June 24th, 2009 at 3:59 am
That could be part of the difference – whole grain flour is not the same as whole grain kernels.
Never cut things from your life that are doing well for you. 🙂
June 24th, 2009 at 7:42 pm
I didn’t mean “cut out” grain but “cut” as in “steel cut” oats. As you know, I believe in minimal processing….having said that, I have read that certain veggies (can’t remember which) are more nutritious if cut and set aside for a few minutes before cooking or eating. May have been garlic and broccoli.
June 24th, 2009 at 8:25 pm
I agree with you about the processing issue.
As far as the garlic goes, crushing it appears to be the way to go:
June 28th, 2009 at 12:33 am
Wow, awesome findings. However, even though whole grain bread is no better than processed “white bread” in terms of promoting healthy blood sugar levels, I’m still going to have to stick with whole grain. I’m much more familiar with that type and, in my opinion, it’s a lot more taste gratifying.
June 28th, 2009 at 2:32 pm
I don’t eat many grains myself but I’d be hesitant to make the switch from less refined “whole grains” to the more refined variety. The key, I think, is to make sure that even the whole grains are doing your body good.
April 18th, 2010 at 12:53 pm
I love the advice about carrots! They really do taste better if you cook them before you cut them! thanks!
April 18th, 2010 at 1:41 pm
Thank you, Liz! 🙂
February 10th, 2015 at 5:35 pm
Update: Study questions health benefits of whole grains …
J Nutr. 2015 Feb;145(2):215-21.
Increased whole grain consumption does not affect blood biochemistry, body composition, or gut microbiology in healthy, low-habitual whole grain consumers.
Whole-grain (WG) foods have been suggested to reduce the risk of cardiovascular disease, but studies are inconsistent and effects on cardiovascular risk markers are not clear.
The objective of this study was to assess the impact of increasing WG consumption to at least 80 g/d on overall dietary intake, body composition, blood pressure (BP), blood lipids, blood glucose, gastrointestinal microbiology, and gastrointestinal symptoms in healthy, middle-aged adults with habitual WG intake <24 g/d.
Eligible subjects [12 men, 21 women, aged 40-65 y, body mass index (BMI): 20-35 kg/m(2)] were identified through use of food frequency questionnaires and subsequently completed 3-day food diaries (3DFDs) to confirm habitual WG consumption. Subjects consumed diets high in WG (>80 g/d) or low in WG [<16 g/d, refined-grain (RG) diet] in a crossover study with 6-wk intervention periods separated by a 4-wk washout. Adherence was achieved by specific dietary advice and provision of a range of cereal food products. The 3DFDs, diet compliance diaries, and plasma alkylresorcinols were used to verify compliance.
During the WG intervention, consumption increased from 28 g/d to 168 g/d (P < 0.001), accompanied by an increase in plasma alkylresorcinols (P < 0.001) and total fiber intake (P < 0.001), without any effect on energy or other macronutrients. Although there were no effects on studied variables, there were trends toward increased 24-h fecal weight (P = 0.08) and reduction in body weight (P = 0.10) and BMI (P = 0.08) during the WG intervention compared with the RG period. CONCLUSION: A combination of dietary advice and provision of commercially available food items enabled subjects with a low-moderate habitual consumption of WG to substantially increase their WG intake, but there was little effect on blood biochemical markers, body composition, BP, fecal measurements, or gut microbiology. Be well! JP
February 19th, 2017 at 12:27 am
Br J Nutr. 2017 Jan;117(2):325-334.
Prospective association between consumption frequency of organic food and body weight change, risk of overweight or obesity: results from the NutriNet-Santé Study.
A lower BMI has been reported among consumers of organic foods, but this relationship has never been examined in a prospective design study. Our aim was to prospectively investigate the association between frequency of organic food consumption and weight change. We analysed data from 62 224 participants of the NutriNet-Santé cohort (78 % women, mean age=45 years) with information on consumption frequency of organic foods, dietary intake and repeated anthropometric data. For sixteen products, participants reported their consumption frequency of labelled organic foods (never, occasionally, most of the time). An organic score (OS) with a maximum of thirty-two points was computed. The associations of the OS (modeled as quartiles (Q)) with change in BMI during follow-up (on average 3·1 years) and with the risk of overweight and obesity were estimated by ANCOVA and multivariable logistic regression. A lower BMI increase was observed across quartiles of the OS (mean difference Q4 v. Q1=-0·16 (95 % CI -0·32, -0·01). An increase in the OS was associated with a lower risk of overweight and obesity (among non-overweight and non-obese participants at inclusion): OR for Q4 v. Q1 were 0·77 (95 % CI 0·68, 0·86) and 0·69 (95 % CI 0·58, 0·82), respectively. Concerning obesity risk, the association was stronger among participants with higher adherence to nutritional guidelines. This study supports a strong protective role of consumption frequency of organic foods with regard to the risk of overweight and obesity that depends on overall dietary quality. Upon confirmation, these results may contribute to fine-tune nutritional guidelines by accounting for farming practices in food production.