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#438: Diet, Brain Health & Cognitive Function May 17, 2022

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Some cognitive decline is normal with age. However, more significant cognitive decline is primarily due to disease-induced dementias (such as Alzheimer's Disease). It also results from neurodegenerative disorders and chronic, prolonged degeneration of our neuronal pathways and functions. Drug discovery for dementias have been largely unsuccessful, leaving no good treatments for this collection of diseases. This had led to research examining areas that may aid in preventing (or more accurately, slowing) cognitive decline. In this episode the Sigma team look at the published data on a variety of nutrients, foods and dietary patterns, including: vitamin D, omega-3 fatty acids, B vitamins, caffeine, flavanoids, coffee and green leafy vegetables.

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[00:02:01] Definitions
[00:08:40] What causes cognitive decline? Dementia? Mechanisms of ND pathogenesis.
[00:11:33] Why might nutrition play a role?
[00:18:18] Dietary patterns
[00:26:30] Diet interaction with APOE genotype
[00:31:18] Alcohol
[00:36:36] Polyphenols - mechanisms
[00:43:05] Coffee & Caffeine
[00:45:03] Flavanoids
[00:51:04] Vitamin D
[01:04:22] Omega 3 fatty acids
[01:21:42] B vitamins & green leafy veg
[01:30:35] Vitamin E
[01:38:24] How to assess cognitive health in ageing intervention studies
[01:45:28] Concluding thoughts

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#437: GMOs & Genetic Engineering: Harmless or Health-Hazard? May 10, 2022

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The issue of genetic enginnering in the food system is one that is often charged with emotion and strong opinion. Indeed, there has been much concern voiced over the years about the potential harms to both human health and the environment of genetically-modified (or more accurately, genetically-engineered) crops. Some concern takes the form of outright hysteria, while other concerns are more nuanced and subtle. Among these concerns, which have good evidence to support them? What regulation is currently in place? Why are their differences between the US and the EU? On the opposite side, there are clear advantages to GE crops; including disease resistance, herbicide tolerance, and even enhanced nutritional content. But are these advantages possible without harm? Do the pros outweigh the cons? In this episode, Alan and Danny discuss the current evidence on genetically engineered crops (or GMOs) and their effect on human health, biodiversity, and the economy.

02:02 – Framing of the GMOs debate
13:52 – Key definitions
20:34 – Where do GMOs show up in the food supply? And jurisdiction differences
33:40 – Impacts on human health and nutritional differences
45:16 – Impact on biodiversity
1:01:57 – What's the deal with glyphosate herbicide?
1:05:34 – Concluding thoughts

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#436: Charlene Van Buiten, PhD – Coeliac Disease & the Search for Novel Therapies May 03, 2022

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Coeliac disease is an autoimmune disorder stimulated by the ingestion of gluten, a protein found naturally in wheat, barley and rye. The condition affects approximately 1% of the Western world. However, currently the only approved treatment for coeliac disease is adherence to a gluten-free diet for life.

Therefore there is much research underway to develop alternative treatment options that may help these patients. One novel antigen-focused therapy that has been hypothesised is the use of plant bioactives.

Specifially, in vitro work by Dr. Charlene Van Buiten has looked as whether there is a mechanism by which polyphenols from green tea could be of benefit. Her work shows that these polyphenols can mitigate gliadin-mediated inflammation and intestinal permeability in vitro.

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#435: Fasting & Longevity – Does the Evidence Match the Hype? Apr 26, 2022

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Current discussions relating to health focus on longevity. This may include some who look at lifespan extension, some who talk of delaying or "treating" ageing or those who focus on reducing morbidity within the parameters of normal lifespan.

One propsed intervention that has garnered a lot of excitement, owing to some interesting research, is the potential use of fasting to increase longevity and/or healthspan. Within this broad category, various different dietary interventions have been suggested, including various forms of intermittent fasting, time-restricted eating, dietary restriction of certain nutritients, calorie restriction or a "fasting-mimicking" diet.

But what does the current evidence tell us? Does the evidence actually match the hype? In this episode Dr. Niamh Aspell, Alan Flanagan and Danny Lennon discuss some of the data on fasting and longevity.

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SNP2: "Fish is Bad For You" [PREVIEW] Apr 19, 2022

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While dietary guidelines universally include fish as a food group that can be consumed regularly in a healthy dietary pattern, there are some potential risks of fish consumption that get raised. Some have some legitimacy, for example the frequency of consumption of high-mercury fish. However, other claims can go to extremes ("eating fish is bad for you") that are based in ideology rather than evidence.

In this Quack Asylum episode, we use a video made by a medical doctor as an example of where quackery can raise its head on this topic. Specifically, there are four claims made in the video that we investigate and see if there is any basis to them.

This is a Premium-exclusive episode. In order to listen to the full episode and access the show notes, you will need to subscribe to Sigma Nutrition Premium.

#434: Is a Vegan Diet Really Best for Diabetes? Apr 12, 2022

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Many different diets have been put forward as solutions that treat type 2 diabetes. Some will claim the diet "reverses" diabetes, some say it puts it into "remission", while others more conservatively recommend a diet to manage diabetes symptoms in a healthy way.

There has been some debate on the use of terms like reversal, cure or resolution. And recently more clarity has been found in defining each.

One of the diets that has been recommended by some for the purposes of "reversing" or treating diabetes is a low-fat, whole food plant-based (WFPB) diet. Specifically, there is a claim that it is superior to other diets in treating diabetes. Some of these claims relate to popular online diet & lifestyle programs that use such a diet. While there is also a number of studies that are commonly cited in support of the claims.

In this episode, we evaluate these claims by looking at the published research in this area, across epidemiology, human intervention trials and mechanistic rationale. We also ponder what it means for something to be the "best" diet to treat a chronic disease.

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#433: Greg Potter, PhD - The Bidirectional Relationship Between Sleep and Diet Apr 06, 2022

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The relationship between our diet and sleep is bi-directional; i.e. sleep impacts diet and diet impacts sleep. Therefore, we can examine the impact of sleep timing, duration and other dimensions on our dietary intake. And then also examine the impat of both overall diet and specific nutrients on improving/worsening sleep. The is clear evidence of distinct, acute effects of restricted sleep time on food preferences, eating behaviour, energy intake, and our underlying metabolic physiology. When it comes to the ability of certain foods or nutrients to improve sleep, often many claims are based on weak evidence or mechanistic reasoning. But there is evidence showing some impacts of certain compounds to either positively or negatively impact sleep. So what is the accurate way to look at this bi-directional relationship? In this episode, Greg Potter, PhD discusses the evidence to date. Dr. Potter received his PhD from the University of Leeds, where his research focused on circadian rhythms, sleep, nutrition, and metabolism. In this episode:

03:15 - Sleep architecture and dimensions of sleep
10:29 - Influence of sleep on diet
35:11 - Chronotypes
53:26 - Impact of diet/meals on sleep
59:50 - Supplements like melatonin and tryptophan
1:20:27 - Rescuing a poor night's sleep - caffeine and nootropics
1:40:31 - Key Ideas segment (Premium only)

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#432: Bill Harris, PhD - Omega-3 Fatty Acids & Health Mar 30, 2022

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Omega-3 fatty acids have long been associated with various health outcomes. A type of omega-3 called alpha-linolenic acid (ALA) is found in various plant foods such as flax seeds or chia seeds. Other omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are found typically in marine food sources such as oily fish (e.g. salmon, mackerel) and algae. And while higher intakes of such foods have shown benefit, there has been some confusion over the benefit of such nutrients due to some large omega-3 supplementation trials reporting null findings. So what should we make of the current evidence base? Does supplementation lead to heart disease risk reduction or not? Do we need direct sources of EPA and DHA in the diet? Does ALA have unique benefits? What is an omega-3 index and why is it important? In this episode, fatty acid expert Dr. Bill Harris dives into each of these questions and clarifies what the current evidence tells us about the effect of these fatty acids on our health. Overview:

04:02 - Fatty acid definitions/subtypes
09:14 - Omega-3 status & the Omega-3 Index (O3I)
20:03 - Omega-3 supplementation trials for CVD
41:15 - DHA, brain health, cognition in later life, development, etc
49:45 - Should we be concerned about omega-6 fatty acids?

Show note available at: sigmanutrition.com/episode432/

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#431: Artificial Sweeteners - Health Impacts and 'Safe' Levels Mar 24, 2022

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There is now widespread use of various "artificial sweeteners" in foods and beverages. Most commonly non-nutritive sweeteners are used to sweeten a products, whilst having less sugar and calories than a traditionally sugar-sweetened version of that product. For example, diet drinks (e.g. diet soda) are most commonly associated with artificial sweeteners. However, they are also in a wide variety of food products and supplements. For a long-time there has been skepticism and alarm raised about their potential health effects. From claims of them increasing our food intake, all the way to causing cancer. And food safety authorities have conducted rigorous examinations of the safety data on each of these compounds. In this episode, the Sigma team discuss the initial research that raised alarm bells, the current process of safety evaluation for non-nutritive sweeteners, the amounts they are consumed in, and the studies published thus far examining their health impacts. Access show notes here.

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SNP1: "Don't Eat Vegetables" [Preview] Mar 17, 2022

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In this Premium episode Alan and Danny aim to address the idea that you shouldn't eat vegetables, or that they aren't beneficial. Two related ideas have been circulated in some nutrition/health communities on the internet:

Vegetables aren't beneficial for health (or that there is no health benefit to high vegetable intake).
Vegetables are actually detrimental to health, and their removal improves health.

Such advice is usually defended through some combination of the following claims, which we examine in this episode:

Humans are naturally carnivores, or have evolved to thrive on animal foods, and only turn to plants in times of famine.
Certain indigenous populations such as the Inuit or the Masai, eat close to no vegetables, yet have robust health.
Many of the nutrients present in vegetables can be obtained from animal foods. And beyond that, these nutrients are more bioavabilable when coming from animal sources.
Fibre is not an essential nutrient, and high-fibre diets don't lead to the health benefits that are typically claimed.
Certain compounds in plants are actively harmful to us. Some of these compounds are natural pesticides, aimed to hurt us. Others are anti-nutrients, which decrease absorption of other key nutrients.
Plants/vegetables contain compounds/nutrients exacerbate clinical conditions such as IBS or autoimmune disorders, and removing all plants including veg, leads to improved outcomes in these people.
There is no benefit to a diet high in vegetables compared to a diet with low/no vegetable consumption.

Premium subcribers can access the detailed study notes to this episode here. Click here to subcribe to Sigma Nutrition Premium.

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