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Burak

McDougall was (almost)right after all?

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From this meta-analysis (thanks to AlPater):

 

http://ajcn.nutrition.org/content/early/2017/04/26/ajcn.117.153148.full.pdf

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ABSTRACT

*Background: Suboptimal diet is one of the most important factors in preventing early death and disability worldwide.

*Objective: The aim of this meta-analysis was to synthesize the knowledge about the relation between intake of 12 major food groups, including whole grains, refined grains, vegetables, fruits, nuts, legumes, eggs, dairy, fish, red meat, processed meat, and sugar-sweetened beverages, with risk of all-cause mortality.

*Design: We conducted a systematic search in PubMed, Embase, and Google Scholar for prospective studies investigating the association between these 12 food groups and risk of all-cause mortality. Summary RRs and 95% CIs were estimated with the use of a random effects model for high-intake compared with low-intake categories, as well as for linear and nonlinear relations. Moreover, the risk reduction potential of foods was calculated by multiplying the RR by optimal intake values (serving category with the strongest association) for risk-reducing foods or risk-increasing foods, respectively.

*Results: With increasing intake (for each daily serving) of whole grains (RR: 0.92; 95% CI: 0.89, 0.95), vegetables (RR: 0.96; 95% CI: 0.95, 0.98), fruits (RR: 0.94; 95% CI: 0.92, 0.97), nuts (RR: 0.76; 95% CI: 0.69, 0.84), and fish (RR: 0.93; 95% CI: 0.88, 0.98), the risk of all-cause mortality decreased; higher intake of red meat (RR: 1.10; 95% CI: 1.04, 1.18) and processed meat (RR: 1.23; 95% CI: 1.12, 1.36) was associated with an increased risk of all-cause mortality in a linear dose-response meta-analysis. A clear indication of nonlinearity was seen for the relations between vegetables, fruits, nuts, and dairy and all-cause mortality. Optimal consumption of risk-decreasing foods results in a 56% reduction of all-cause mortality, whereas consumption of risk-increasing foods is associated with a 2-fold increased risk of all-cause mortality.

*Conclusion: Selecting specific optimal intakes of the investigated food groups can lead to a considerable change in the risk of premature death.

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We can see that the optimal diet for general population is actually a McDougall diet (plus fish) which is based on whole grains and legumes (starches) with the addition of some fruits and vegetables, and fish (no one is perfect). Therefore, no supplement is necessary and it is also suitable for elderly since pure McDougall diet most likely be suboptimal for them.

IMO, the strength of WGs&legumes is their ability to provide enough calories while satisfying most of the nutrient intake. Fruits&vegetables&nuts provide variety of antioxidants, polyhenols etc., but it gets saturated after some point. Fish fills the holes by providing other key nutrients such as B12, selenium, iodine, omega-3 as well as easy protein for elderly.

Edited by Burak

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I don't think McDougall gets any particular credit here: these guidelines are consistent with what the Dietary Guidelines for America and its international equivalents have been saying for 30 years or more (with the semi-exception of nuts), and basically the entire public health community. One could just as easily have said "Atkins was right after all ... We can see that the optimal diet for general population is actually an Atkins diet (plus whole grains) which is based fruits and vegetables, nuts, and meat."
 
Also, McDougall is an anti-nut nut (sic), as he is against all  high-fat foods, even though the evidence supporting nuts and EVOO are quite strong — stonger, certainly, than for whole grains or fruit & veg (no cliniical trials with hard outcomes for all of the latter).

 

A near-vegan, very-low-fat diet is the sine qua non of McDougall, and those features are unaddressed by and to a degree actively undermined by the findings of this meta-analysis (by way of the nuts). Indeed, the quantities involved here even of the endorsed foods couldn't make up a McDougall diet (eg, highest intake of whole grains 110 grams).

 

And, as usual, the analysis used to construct the part of this meta-analysis on whole grains is dodgy: they only looked at quantitative intake, without looking at displacement effects — ie, people who eat more whole grains tend to be eating them at the expense of refined grains, but those were each analyzed independently. Whether there is a positive benefit for whole grains is thus not addressed, as vs. avoidance of refined ones. (Cf. Chowdhury et al and the many similar meta-analyses falsely claiming to absolve SaFA from a role in cardiovascular disease).

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I am a little skeptical about fish. How much fish is needed to provide enough B12 and n-3s, and how much Mercury, PCBs, and other contaminants the same quantity of fish contains?

 

I'm sure there is not a unique answer (pollution varies in function of geographical areas and wild vs farmed fish), the doubt is a legitimate one though.

 

McDougall is strongly anti-nuts and anti-oils (all kind of oils). His bias would make sense in a heavily calorie-restricted diet where it is desired to maximize the bulk of food to get more satiated. I believe that would be solved by lots of bulky vegetables, one ounce of nuts and one third of a tablespoon of Torre di Mossa EVOO from De Carlo in Italy. That's an EVOO extremely rich in polyphenols.

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In Kirstine Bell's PhD thesis she generated insulin index tables of foods and also did some interesting work looking at foods in combination.  It turns out that fat which is usually considered to not be insulinogenic is not as simple as commonly believed.  In combination with protein, fat can blunt the insulin response quite markedly but in combination with carbohydrates it does the opposite.

 

Which makes for some interesting results that I think explains how both McDougall and Atkins are at least partially right about fat.  First if one is consuming a high carb diet, especially with fast digesting refined starches and sugars, adding fat makes it worse. And foods like nuts and eggs which are high in protein but also high in fat have lower insulin index scores than an equivalent amount of protein from supposedly healthy lean meats such as chicken breast.

 

And when indulging in protein to provoke insulin, such as a post workout whey concentrate drink, one will get a stronger effect by limiting fat and allowing for a moderate amount of carbs (hopefully not in excess of that required to replenish glycogen).

Edited by Todd Allen

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I am a little skeptical about fish. How much fish is needed to provide enough B12 and n-3s, and how much Mercury, PCBs, and other contaminants the same quantity of fish contains?

You're assuming, wrongly in my view, that the benefits of fish can be reduced to B12 and n3s, and engaging more broadly in "nutritionism."

 

McDougall is strongly anti-nuts and anti-oils (all kind of oils). His bias would make sense in a heavily calorie-restricted diet where it is desired to maximize the bulk of food to get more satiated. I believe that would be solved by lots of bulky vegetables, one ounce of nuts and one third of a tablespoon of Torre di Mossa EVOO from De Carlo in Italy. That's an EVOO extremely rich in polyphenols.

Indeed. My diet has at different times been 30-40% fat, with the %fat usually rising as total Calories decline; even at 1800 Cal and 36% fat, my meals were enormous by "normal" standrds. Basing your diet on grains is a much more serious volume-killer.

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How ironic that we are discussing olive oil in McDougall topic, haha:)

 

He is strongly against any kind of separated oil, but he never says nuts are unhealthy. Since his program is mostly aimed for weight loss, he recommends no oil and nuts, but also admits that nuts are probably healthy. 

 

About the study, even refined grains are not associated with negative health outcomes, and whole ones are associated with greater health. Please also note that after some point, further vegetable consumption does not improve outcomes. I think that doesn't mean vegetables are not healthier than whole grains, but rather their inability to replace other unhealthy food groups because of insufficient satisfaction. You cannot replace bacon and egg breakfast with tomato and lettuce alone, it just doesn't work for most of the people. You can change it with oatmeal breakfast though, so you obtain quadruple improvement, i.e. staying away from unhealthy group and eating from healthy group at the same time.

 

This is the reason why I like McDougall's emphasis on starches rather than fruits and vegetables. If you overemphasize vegetables, you will fail in the long run and go back to your former diet, on the other hand, if you satisfy yourself with healthy starches you will be content and stick with the diet.

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How ironic that we are discussing olive oil in McDougall topic, haha:)

Yeah ... Mccoy, Sibiriak, Gordo: with your permission, I'd like to split off your discussion of EVOO sourcing into a separate thread.

 

He is strongly against any kind of separated oil, but he never says nuts are unhealthy. Since his program is mostly aimed for weight loss, he recommends no oil and nuts, but also admits that nuts are probably healthy.

Ahem: aside from the canard that nuts are obesogenic (studies consistently show they promote weight loss), see this nonsense:

 

Nuts May Hurt the Bones Too

High-protein foods in Western diets, especially hard cheeses, meat, poultry, eggs, fish, shellfish, and foods made with isolated soy proteins, generate a large amount of acid in the body after eating them.13 This acid must be neutralized, primarily by the release of alkaline materials from the bones; and thus begins bone loss and osteoporosis. 14-17  [/size]

The storage organs—nuts, seeds, legumes, and grains—are rich in nutrients, including proteins, which result in the delivery of a small net acid load to the body. (The amount of acid caused by animal food consumption is 6 to 10 times greater than that caused by plant storage organs.)13 A study of people on a Mediterranean diet supplemented with an ounce of nuts (walnuts, hazelnuts, and almonds) daily for three months, found evidence of adverse effects on their bones.18 There was an elevation in their parathyroid hormone levels and a slight increase in breakdown products of bone (deoxypyridinoline) found in the nut-eaters’ urine.  [/size]

 

Fortunately, most healthy plant-food-based meal plans also include foods that are alkaline, meaning fruits and vegetables, which neutralize the small amount of dietary acids that come from eating nuts, seeds, legumes, and grains.11 However, this observation should also serve as a word of caution that even a whole foods vegetarian diet has the potential to cause problems of over-nutrition from excess calories, fat, protein, and dietary acids, and adding in green and yellow vegetables and fruits is important.[/size]

 

About the study, even refined grains are not associated with negative health outcomes, and whole ones are associated with greater health.

That's technically true, but look at the actual details of the study. The meta-analysis was highly powered to detect effects of whole grains (Nineteen studies with 121,141 mortality cases), and only weakly powered to detect effects of refined grains (Four studies with 11,034 mortality cases — note that in addition to the raw magnitude of the numbers, the mortality ratio was more than twice as high in the whole grains studies). And the trend for refined grains was negative past 100 g (see Fig. 2).

 

Please also note that after some point, further vegetable consumption does not improve outcomes. I think that doesn't mean vegetables are not healthier than whole grains, but rather their inability to replace other unhealthy food groups because of insufficient satisfaction. You cannot replace bacon and egg breakfast with tomato and lettuce alone, it just doesn't work for most of the people. You can change it with oatmeal breakfast though, so you obtain quadruple improvement, i.e. staying away from unhealthy group and eating from healthy group at the same time.

 

This is the reason why I like McDougall's emphasis on starches rather than fruits and vegetables. If you overemphasize vegetables, you will fail in the long run and go back to your former diet, on the other hand, if you satisfy yourself with healthy starches you will be content and stick with the diet.

That doesn't make it a healthier diet for people actually practicing it.

 

IAC, however reasonable that may sound to you, in practice people have not been willing to stick to a McDougall diet. Ornish's diet books were bestsellers in the 80s, and McD's own had a pretty good run, but almost no one practices their kind of diet.  You may think people won't trade bacon and eggs for vegetables, but in practice they're also not willing to indefinitely forego them for  oatmeal.

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Burak, I find McDougall a formidable figure of a nutritionist, but we must admit he has his dietary foibles (oils, nuts, soy products).

 

I read his maximum weightloss book and I must say I was favourably impressed. Pls note though that, in his weightloss plan, he puts a lot of vegetables on the plate before the starch, and make people snack on bits of raw veggies in between meals. He also restricts the starch, eliminating all flours and pasta. Only whole grains like rice, barley and so on are admitted (slower digestion=lesser glycaemic peak). Interestingly, white potatoes are allowed and suggested. 

 

McDougall's diet would make a perfect example of nutritional geometry according to recent articles from Solon-Biet et al., posted in another thread. A 1:10 protein to carbs ratio according to such articles is proposed as the most favourable to longevity (for worms, flies and rats). Interestingly, such a ratio can be mantained in practice only lowering dietary fat to 5% or less. Actually, the Okinawan diet is taken as a real life example. It's also true that's maybe the only example in the world, barring a few fructarians.

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The EVOO sourcing discussion has been moved to its own thread: Everyone who was following that discussion, make sure that you click the 'follow this topic' button in the upper right hand side of the new thread to maintain your alerts.

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