Help With Scientific Studies:

science

(Ryan L Sink) #1

Hi, I am not a medical professional myself and therefore am not able to see the quality of scientific data followers/critics of mine present me with.

Here is one for example on ‘low-carb’ diets and all-mortality rate. Are there any noticeable holes for you in this study? To my uneducated eyes, it seems like there is no real empirical data here and also the amount of protein as well as carbohydrate sources seem ambiguous.

I’d appreciate your help on the matter!


(John) #2

I’ll try to dive in a little in a while, but just know that observational studies are pretty much the worst type, only made worse my doing a meta-analysis of a bunch of them. I wouldn’t call it science or a study at all, it is essentially finding a bunch of information related to what you are wanting to know and creating correlations.

Edit: They did a pretty good job of summing it up, we found this thing but it is probably nothing.

Low-carbohydrate diets were associated with a significantly higher risk of all-cause mortality and they were not significantly associated with a risk of CVD mortality and incidence. However, this analysis is based on limited observational studies and large-scale trials on the complex interactions between low-carbohydrate diets and long-term outcomes are needed.


#3

Statistical mumbo-jumbo is not my strong point.

From the review:

Although the majority of the enrolled subjects were middle-aged and free of such chronic comorbidities as diabetes and coronary heart disease, healthcare professionals dominated in the US cohorts, who may not truly represented the average population in the community.

So, basically gathered from studies of healthy people.

However, this analysis is based on limited observational studies and large-scale trials on the complex interactions between low-carbohydrate diets and long-term outcomes are needed.

A quick look at the type of studies they used. There are 9 studies included in the review data, listed here: Table of studies. The ones without asterisks were used.

[29] 78,779 US women who were free of cardiovascular disease and diabetes in 1980 and completed a food frequency questionnaire.

[30] 82,802 women in the Nurses’ Health Study who had completed a validated food-frequency questionnaire.

[31] Associations of glycemic index and glycemic load with incident CVD were examined in a prospective cohort of 15,714 Dutch women age 49 to 70 years without diabetes or CVD. Dietary glycemic index and glycemic load were calculated using the glycemic index, carbohydrate content, and frequency of intake of individual foods.

[11] 42,237 women, 30-49 years old at baseline, volunteers from a random sample, who completed an extensive questionnaire and were traced through linkages to national registries until 2003.

[12] Participants were 22 944 healthy adults, whose diet was assessed through a validated questionnaire. Participants were distributed by increasing deciles according to protein intake or carbohydrate intake, as well as by an additive score generated by increasing decile intake of protein and decreasing decile intake of carbohydrates.

[7] Limitations - Diet and lifestyle characteristics were assessed with some degree of error, however, sensitivity analyses indicated that results were not unlikely to be substantially affected by residual or confounding or an unmeasured confounder.

[8] Dietary habits were determined by 7-d dietary records in a population-based longitudinal study of 924 Swedish men (age: 71 ± 1 y).

[9] Women aged 30-49 years, residing in the Uppsala healthcare region in Sweden in 1991-92, were the source population for the Swedish Women’s Lifestyle and Health Cohort. For this cohort, 96 000 women were randomly selected from four age strata (30-34, 35-39, 40-44, and 45-49), invited by mail to participate, and asked to fill in a questionnaire and return it in a pre-paid envelope.

[10] Median intakes of carbohydrates, protein and fat in subjects with LCHP scores 2-20 ranged from 61.0% to 38.6%, 11.3% to 19.2% and 26.6% to 41.5% of total energy intake.


(Kristin Rogers) #4

This is not terribly low carb – 38-60% of calories from carbohydrate. Not sure if this is from a particular study, or the aggregate that they based the analysis on.

The other huge red flag is that most of the data is diet recall questionnaire. This is the squishiest of data, and I don’t give it much credence. Memory lapse alone accounts for so much error, plus if there is a tendency to give the “right” answer, whatever that may seem to be it gets further skewed.

Even if the data on the diet recall questionnaire were magically 100% accurate, diet is not the only thing related to mortality. So if the allegedly low carb folks had some other dangerous lifestyle feature, we don’t know.

I need to retake my statistics and epidemiology courses…


#5

That’s from study #10 in the notes. [They excluded a lot of studies that didn’t meet their guidelines] https://www.ncbi.nlm.nih.gov/pubmed/22333874


(Ryan L Sink) #6

Thank you all so much for your help! I have used as much of this as possible in a discussion with a friend of mine on Facebook. You can see the post and comments here: https://www.facebook.com/ryansink/posts/10100289285157304

Please feel free to find holes in what I said there as well!

Do you guys also get bombarded by people trying to prove this wrong?


(ianrobo) #7

Hi @Ryan_L_Sink , interesting debate on your link.

Ryan L. Sink I’m experienced in undergoing a nutritional ketogenic diet as I was on a cyclical ketogenic protocol for around 2 years. My SNPs are not good at all for high fat, and I had some health consequences that I’m still recovering from.

I will highlight the above, I would mention to your friend that there is no such thing as a cyclical ketogenic protocol, it means IMHO that he has never been fully fat/keto adapated. He mentions that he has had a DNA test and not good for fat absorption then that will explain why he is cycling in and out, he is someone for which our WOE is NOT suitable and as simple as that.

But the guy seems to be advocating plant based so is he a vegan and as discussed elsewhere they tend to pick and choose their studies. If when he switched to Keto and was getting a lot of his fat from plant based oils then may explain why he had problems ?


(Ryan L Sink) #8

I will pass all of this on to my friend, thanks again.

By the way: What are your go-to studies and data for showing the benefits of nutritional ketosis and busting myths such as cholesterol being the primary cause of CVD?


#9

There’s a list of the studies discussed on the 2KetoDudes podcast #69 here: http://2ketodudes.com/show.aspx?episode=69


(Ryan L Sink) #10

One final question:

Carl and Richard claim that humans have evolved to be fat burners 11 months out of the year. Is there any data I can use as a reference to support this claim?

I’m doing a webinar in a few days and would love to use this in there, but only if I know that I can support what I am saying or at least refer to a reliable source which claims this.

Thanks!


#11

Ryan,

I’m not sure if this will help - and actually I only skimmed the answers above so some of it might have been covered - but Denise Minger does a terrific job of pulling apart various scientific studies and I’ve learned a lot from reading her work. If I remember correctly, both the China Study and Forks Over Knives get a rather long (and very funny) treatment on her blog.

That’s specific advice about studies, but a more general one that I would give after watching endless discussions about this kind of thing online: you can never win these kinds of arguments and they can be a huge waste of time and rather stressful. Person A points to this study, and you can pull it apart quite effectively - “low carb” turns out to be 200g per day; and/or it shows only correlation rather than causation; and/or the whole thing presupposes that higher total cholesterol is bad; and/or the fat they use on the poor mice is canola oil; and/or they are trying to extrapolate cholesterol questions based on what they feed rabbits* - but then the other person finds something not right in your reasoning of item C on your list, and while you’re coming back with a clarification on that, he points to another study, and another one, then pulls out a personal anecdote … and that can go on FOREVER.

It’s important to really follow the science for what you do and what you recommend to others, mostly because you want to be sure of what you’re doing and feel confident in making recommendations - but that’s different from the argument and counter argument ad infinitum that tends to happen around these questions.

*yes, that really happened. Somebody thought that it was a good idea to feed animal fats to herbivores and then use the results to make recommendations for humans: “See how they all developed CVD when we fed them animal fats! Animal fats are bad for us!”


(Ryan L Sink) #12

Thanks Madeleine!


#13

Seasonality of indigenous and natural high carb foods?