Absolutely not. “The Nutrition Proposition” is strictly a book about adult nutrition. I purposely avoided entering into the evidence fray that encompasses issues around nutrition in children and pregnancy because there is actually far less evidence in these groups and what there is, is much trickier to decipher.
Population health is about the health outcomes of a group of individuals. However, population health is obviously solely dictated by the actions of many individuals. Population health is clearly very important, but the purpose of “The Nutrition Proposition” is to provide YOU with a reasonable synopsis of the best available evidence around the impact nutrition might have on YOU to help YOU decide what YOU should eat.
In “The Nutrition Proposition” I discuss very little about mechanism of action type (basic science) evidence or animal research evidence. Some people likely will take umbrage to the fact I have ignored this evidence avenue. As an example, Katz et al in 2019 discussed the debate around the nature of evidence that should used to support nutrition recommendations.1 They suggested that while putting randomized controlled trials at the top of the evidence hierarchy is appropriate for medications and discrete procedures there are methodological limitations and ethical limitations that trials have when it comes to assessing the impact of nutrition on health outcomes. They argue cohort studies may be more informative than trials when it comes to lifestyle interventions. They go on to suggest if you can’t do trials then you should use a different evidence construct. The construct this group developed was called HEALM (Hierarchies of Evidence Applied to Lifestyle Medicine). They argue this approach allows us to use “specific contributions of diverse research methods to understand lifetime effects of health behaviors”. There arguments certainly deserve merit but interestingly not everyone agrees. Zeraatkar et al suggest that “Rules for determining the quality of evidence should not depend on the feasibility of particular research designs and should be consistent across health fields”.2
Regardless of the debate, what specifically did HEALM suggest when it comes to the strength of the evidence. Well, they developed 4 categories of evidence which are outlined in the table.
Hierarchies of evidence
Strength of evidence
Score (taken from the points on the left)
Mechanism of action – (bench science or animal models)
Large population (for generalizability) cohort studies
Long-duration (over decades) cohort studies
Randomized controlled trials
As you can see, even if one had bench science and a large population cohort study the strength of evidence would still be considered as insufficient or weak evidence. So, when you see nutritional arguments in which a person only presents bench science or animal model research (and this happens a lot in nutrition) remember that the person’s argument is considered at most to be insufficient/weak. And even the people (Katz) who argue we should use a different hierarchy agree based on their new hierarchy.
So, the opinion overall is that cohort studies and randomized evidence clearly still rule the day when it comes to the strength of evidence no matter how you look at it. Personally, I believe, the opinions of ‘experts’ who rely predominantly on mechanisms of action or simply discuss what specific compounds are found in food, without at least to some degree backing up their recommendations with well-designed trials or cohorts, should pretty much be ignored. Now I’m not saying they aren’t right. I’m just saying that no one can know if they are right OR wrong given the weakness of this type evidence.
Finally, when it comes to nutrition research evidence, some people suggest that even cohort studies have too many limitations to be considered reliable and that nutrition research must apply reproducible and valid methodologies as is done in drug trials. That is a laudable goal but it is highly unlikely this will ever be done to answer even a very small percentage of the 100s if not 1000s of legitimate nutritional questions. The bottom line is that if cohort studies are pretty much fatally flawed 3,4 then we are left with only randomized controlled trials of which, when it comes to clinically important outcomes, we have only a handful. Personally, I believe that well designed cohort studies that show consistent findings can provide us with at least some insight as to what specific aspects of nutrition might contribute to human health,
Pretty much any nutrition evidence is definitely far from perfect. As Satija 2015 points out it is very difficult to measure diet accurately, and that “the human diet is a complex system of interacting components that cumulatively affect health”. 5
There is no doubt outcomes such as heart attacks, strokes and death are more important than surrogate markers. Surrogate markers are only relevant because they are believed to be associated with these important clinical outcomes. There are many examples where we have changed some surrogate markers and this has not led to changes in clinical outcomes. But to be fair there have also been lots of trials that have shown that changing surrogate markers leads to important changes in clinical outcomes. So, for that reason, in “The Nutrition Proposition” I have provided the best available evidence I could find that looked at the impact of nutrition on blood pressure, lipids and glucose. And then, somewhat uniquely from other books, I try to put the magnitude of the surrogate marker changes into a proper clinical context by providing ballpark estimates of what the changes could theoretically do to your risk of heart attacks and strokes – which are really the important outcomes after all.
I obviously haven’t looked at every trial/study for every topic but I attempted to find recent, relevant, well-done systematic reviews of trials or cohorts that have looked at the impact on clinically important outcomes. When there were no systematic reviews, I included the key cohort studies or randomized controlled trials that were available. I also on occasion discussed whatever evidence people seemed to be using to support their particular stand on a particular nutrition recommendation. Finally, I included any evidence/information that would help me put the evidence into a proper context for you as an individual.
Of course. I would love to see it. If you find any evidence you think fundamentally changes what I’ve written please let me know and if warranted I’ll make changes to “The Nutrition Proposition” – that is the benefit of self-publishing. My email address is firstname.lastname@example.org
That can happen. If you find a mistake send me a note and if needed, I’ll absolutely make corrections. “The Nutrition Proposition” is not about being right it’s about presenting the best available evidence in as clear and correct way as possible so that people can make informed decisions about the food they eat.
I purposely avoided talking about supplements and vitamins in “The Nutrition Proposition” because the amount of evidence (both good and bad) around these could easily fill another book if not more. There are 10,000s of supplements and vitamin products available on the market with varying amounts and combinations of 1000s of different individual items. Each one extolls the benefits on overall health and a multiple of different organ systems. My overall take on the best available evidence for these supplements is that in general supplements provide little if any benefit to most individuals. Dozens of well-designed trials in 100,000s of people have been published over the last 20-30 years and the results almost without fail show that for relatively healthy people without obvious vitamin deficiencies there is no change in death rate, cancer, heart attacks or strokes. Even Vitamin D, one of the most used supplements has been studied so much that some researchers have suggested we don’t need any more Vitamin D trials looking at cardiovascular disease cancer or fractures as they have been shown to do almost nothing to the risk of these outcomes.6 Anti-oxidant vitamins, such as Vitamin A, E or beta-carotene, have been shown to not do anything to prevent cataracts7, no impact on cardiovascular disease8 and increase death for about one in every 300 who take any of those supplements for roughly three to five.9
No when it comes to supplements, there are clearly a few exceptions. Here are a few examples
Those people who are iron deficient who can’t get or absorb sufficient iron from their diet could benefit from low doses of iron.
VITAMINS FOR MACULAR DEGENERATION
There is some evidence for a combination of vitamin C 500 mg, vitamin E 400 IU, beta-carotene 15mg and zinc for age-related macular degeneration. Taking one a day for 6 years decreases the number of people who get a 15 letter decrease in visual acuity from baseline in at least 1 eye from 29% to 23% – a 6% absolute difference.10
FOLIC ACID AND PREGNANCY
Folic acid during pregnancy reduces the chance of neural tube defects from roughly 1.5% down to 0.4%.11
Vitamin B12 should certainly be used in people who are strict vegans?
Other than these isolated examples my typical advice for how people can get the most out of their supplements is as follows.
- After purchasing any vitamin/supplements immediately drive to the house of a friend or family member that is at least five km from your house and ask them to store them in a safe place.
- Every day, when you would normally take one of these pills, simply walk to their house, pop that pill, then immediately walk home. Briskly. The results will astound you. If you want you don’t even need to take the pill – just look at it.
- The greatest benefit from these products would be to package them up and send them to countries where malnutrition and vitamin deficiencies are a serious concern.
The best available evidence I could find for organic foods is as follows
A systematic review in 2012 Ann Intern Med 2012 concluded 12
“The published literature lacks strong evidence that organic foods are significantly more nutritious than conventional foods. Consumption of organic foods may reduce exposure to pesticide residues and antibiotic-resistant bacteria.
A systematic review 7 years later in 2019 Vigar concluded the following13
“Clinical trial research has been short-term and measured largely surrogate markers with limited positive results.”
“Pesticide excretion studies have consistently shown a reduction in urinary pesticide metabolites with an organic diet; however, there is insufficient evidence to show translation into clinically relevant and meaningful health outcomes. “
“Consumption of organic food is often tied to overall healthier dietary practices and lower levels of overweight and obesity, which are likely to be influential in the results of observational research.”
So, based on this, my opinion is that the present evidence-base in no way allows one to make any definitive health claims for organic foods over non-organic foods.
- Katz DL, Karlsen MC, Chung M, Shams-White MM, Green LW, Fielding J, Saito A, Willett W. Hierarchies of evidence applied to lifestyle Medicine (HEALM): introduction of a strength-of-evidence approach based on a methodological systematic review. Bmc Med Res Methodol. 2019;19(1):178. doi:10.1186/s12874-019-0811-z
- Zeraatkar D, Guyatt G, Pablo. Red and Processed Meat Consumption and Risk for All-Cause Mortality and Cardiometabolic Outcomes. Annals of Internal Medicine. Published online 2020. doi:https://doi.org/10.7326/L20-0070
- Taubes G. Epidemiology Faces Its Limits. Science. 1995;269(5221):164-169. doi:10.1126/science.7618077
- Ioannidis JPA. Implausible results in human nutrition research. Bmj Br Medical J. 2013;347(nov14 3):f6698. doi:10.1136/bmj.f6698
- Satija A, Yu E, Willett WC, Hu FB. Understanding Nutritional Epidemiology and Its Role in Policy. Adv Nutr. 2015;6(1):5-18. doi:10.3945/an.114.007492
- Bolland MJ, Grey A, Gamble GD, Reid IR. The effect of vitamin D supplementation on skeletal, vascular, or cancer outcomes: a trial sequential meta-analysis. Lancet Diabetes Endocrinol. 2014;2(4):307-320. doi:10.1016/s2213-8587(13)70212-2
- Mathew MC, Ervin A, Tao J, Davis RM. Antioxidant vitamin supplementation for preventing and slowing the progression of age‐related cataract. Cochrane Db Syst Rev. 2012;(6):CD004567. doi:10.1002/14651858.cd004567.pub2
- Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Cochrane Db Syst Rev. 2012;2012(3):CD007176. doi:10.1002/14651858.cd007176.pub2
- Myung SK, Ju W, Cho B, Oh SW, Park SM, Koo BK, Park BJ, Group KMAS. Efficacy of vitamin and antioxidant supplements in prevention of cardiovascular disease: systematic review and meta-analysis of randomised controlled trials. Bmj. 2013;346(jan18 1):f10. doi:10.1136/bmj.f10
- Group AREDSR. A Randomized, Placebo-Controlled, Clinical Trial of High-Dose Supplementation With Vitamins C and E, Beta Carotene, and Zinc for Age-Related Macular Degeneration and Vision Loss: AREDS Report No. 8. Arch Ophthalmol-chic. 2001;119(10):1417-1436. doi:10.1001/archopht.119.10.1417
- De‐Regil LM, Peña‐Rosas JP, Fernández‐Gaxiola AC, Rayco‐Solon P. Effects and safety of periconceptional oral folate supplementation for preventing birth defects. Cochrane Db Syst Rev. 2015;2015(12):CD007950. doi:10.1002/14651858.cd007950.pub3
- Smith-Spangler C, Brandeau ML, Hunter GE, Bavinger JC, Pearson M, Eschbach PJ, Sundaram V, Liu H, Schirmer P, Stave C, Olkin I, Bravata DM. Are Organic Foods Safer or Healthier Than Conventional Alternatives?: A Systematic Review. Ann Intern Med. 2012;157(5):348. doi:10.7326/0003-4819-157-5-201209040-00007
- Vigar V, Myers S, Oliver C, Arellano J, Robinson S, Leifert C. A Systematic Review of Organic Versus Conventional Food Consumption: Is There a Measurable Benefit on Human Health? Nutrients. 2019;12(1):7. doi:10.3390/nu12010007