Low carbohydrate-high protein diet and incidence of cardiovascular diseases in Swedish women: prospective cohort study

Re: Low carbohydrate-high protein diet and incidence of cardiovascular diseases in Swedish women: prospective cohort study

29 June 2012

The following points need to be made in response to this article:

1) The claimed association, not causation, is extremely small

There were 1,270 recorded incidents of all cardiovascular disease (ischaemic heart disease, ischaemic stroke, haemorrhagic stroke, subarachnoid haemorrhage and peripheral arterial disease) among 43,396 women over 680,745 study years. An incident rate of 0.19%. This means that the women in the study had a 99.81% chance of NOT suffering any cardiovascular events during the long study.

The 8,395 women with a LCHP score of ≥ 16 on their scoring system had a 0.23% incident rate during their 131,262 woman years. This 'highest risk' group, therefore, had a 99.77% chance of NOT suffering any cardiovascular events whatsoever during the 15-16 year study.

The 8,343 women with a LCHP score of ≤ 6 on their scoring system had a 0.14% incident rate during their 130,965 woman years. This 'lowest risk' group, therefore, had a 99.86% chance of NOT suffering any cardiovascular events whatsoever during the long study.

So the 'highest risk' group might expect a 0.04% lower chance of remaining cardiovascular disease free than the average woman in the study. This does not justify the BMJ headline of "Experts warn of significant cardiovascular risk with Atkins-style diets." (My emphasis) (Ref 1)

2) The scoring system is absurd

Bjorn Hammarskjold captures it best: “Low protein is 1, high protein is 10, low carbohydrates are 10, high carbohydrates is 1. So to have sum score of 11 it can be low protein (1) and low carbs (10) or high protein (10) and low carbs (1) or any sum between: 1+10, 2+9, 3+8, 4+7, 5+6, 6+5,7+4, 8+3, 9+2 or 10+1, all give 11 as score.”

What conclusions would this lead to?

3) Atkins is not low carb high protein
Atkins is low carb, whatever protein naturally occurs in food and high fat. This brings us on to:

4) The 'researchers’ do not seem to know the nutritional composition of food

There are three macro nutrients: carbohydrates, fat and protein. All food has at least one macro nutrient, most have two and some have three.

The only foods on this planet with no protein are sucrose and oils. Every other food contains protein. Sucrose is 100% carbohydrate – no fat or protein and oils are 100% fat – no carbohydrate or protein.

Most foods are predominantly carbohydrate proteins (with no fat or little fat) or fat proteins (with no carbohydrate or little carbohydrate). The carb proteins come from the ground and trees and will fall under plant proteins in this article. Fruits, vegetables, grains, pulses, starchy foods are in this category. The fat proteins come from ‘things with faces’ and will fall under animal proteins in this article. Meat, fish, eggs and dairy products are in this category.

This article assumes that the higher the carbohydrate intake and the lower the protein intake, the lower risk of CVD the women shall have. Hence our Swedish women should have eaten nothing but sucrose for 15.7 years and they would have had 100% carb intake and 0% protein intake (and 0% fat intake – presumably also ideal). They would have had no vitamins or minerals, no protein, let alone complete protein and no fat, let alone essential fats, but they would have met the recommendations emanating from this article.

5) Table 1 of the study should have provided the headlines

Table 1 of the study looks at “non-nutritional variables”. Table 1 tells us the following:

- AGE: Women in the 35-39 age group had twice the incidence of cardiovascular events as women in the lowest age group. Women in the 40-44 age group had nearly four times the incidence of cardiovascular events as women in the lowest age group. Women in the 45-49 age group had nearly eight times the incidence of cardiovascular events as women in the lowest age group.

- EDUCATION: Women with fewer than 10 years education had nearly three times the incidence of cardiovascular events as women with more than 13 years education. Women with 11-13 years education had less than half the incidence of cardiovascular events as women in the lowest education group.

- HEIGHT: The shortest group of women in
the study had nearly three times the incidence of cardiovascular events as women in the tallest group.

- BMI: Those with normal BMI have the lowest incidence of cardiovascular events. Underweight woman had almost twice the incidence of cardiovascular events as normal weight women. Overweight women experienced less incidence of cardiovascular events than underweight women, but still 1.6 times that of normal weight women. Obese women experienced nearly three times the cardiovascular events as normal weight women.

- SMOKING: Not surprisingly, smokers have nearly three times the incidence of cardiovascular events as non smokers. Giving up smoking helps but you’re better off not ever having smoked.

- EXERCISE: The lower the activity group, the greater the incidence of cardiovascular events.

The headline should have been "The older women get, the more incidence of cardiovascular events they experience”, but then that wouldn't have been headline news.

Ref 1: http://group.bmj.com/group/media/latest-news/experts-warn-of-significant...

Competing interests: None declared

Zoe Harcombe, Author & obesity researcher

None - self employed, Llanvaches, Gwent , NP26 3AY

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