Fructose bad effects reversed by DHA, an omega-3 fatty acid

Despite alarm signals raised by various groups and organizations regarding the dangers of the presence of sugars – particularly fructose derived from corn syrup – in almost every food in the markets, only in the past decade there has been some serious evidence against high consumption of fructose.

A bitter-sweet (sic!) paper comes from Meng et al. (2016) who, in addition to showing some bad things that fructose does to brain and body, it also shows some rescue from its deleterious effects by DHA (docosahexaenoic acid), an omega-3 fatty acid.

The authors had 3 groups of rodents: one group got fructose in their water for 6 weeks, another group got fructose and DHA, and another group got their normal chow. The amount of fructose was calculated to be ecologically valid, meaning that they fed the animals the equivalent of 1 litre soda bottle per day (130 g of sugar for a 60 Kg human).

The rats that got fructose had worse learning and memory performance at a maze test compared to the other two groups.

The rats that got fructose had altered gene expression in two brain areas: hypothalamus (involved in metabolism) and hippocampus (involved in learning and memory) compared to the other two groups.

The rats that got fructose had bad metabolic changes that are precursors for Type 2 diabetes, obesity and other metabolic disorders (high blood glucose, triglycerides, insulin, and insulin resistance index) compared to the other two groups.

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The genetic analyses that the researchers did (sequencing the RNA and analyzing the DNA methylation) revealed a whole slew of the genes that had been affected by the fructose treatment. So, they did some computer work that involved Bayesian modeling  and gene library searching and they selected two genes (Bgn and Fmod) out of almost a thousand possible candidates who seemed to be the drivers of these changes. Then, they engineered mice that lacked these genes. The resultant mice had the same metabolic changes as the rats that got fructose, but… their learning and memory was even better than that of the normals? I must have missed something here. EDIT: Well… yes and no. Please read the comment below from the Principal Investigator of the study.

It is an ok paper, done by the collaboration of 7 laboratories from 3 countries. But there are a few things that bother me, as a neuroscientist, about it. First is the behavior of the genetic knock-outs. Do they really learn faster? The behavioral results are not addressed in the discussion. Granted, a genetic knockout deletes that gene everywhere in the brain and in the body, whereas the genetic alterations induced by fructose are almost certainly location-specific.

Which brings me to the second bother: nowhere in the paper (including the supplemental materials, yeas, I went through those) are any brain pictures or diagrams or anything that can tell us which nuclei of the hypothalamus the samples came from. Hypothalamus is a relatively small structure with drastically different functional nuclei very close to one another. For example, the medial preoptic nucleus that deals with sexual hormones is just above the suprachiasmatic nucleus that deals with circadian rhythms and near the preoptic is the anterior nucleus that deals mainly with thermoregulation. The nuclei that deal with hunger and satiety (the lateral and the ventromedial nucleus, respectively) are located in different parts of the hypothalamus. In short, it would matter very much where they got their samples from because the transcriptome and methylome would differ substantially from nucleus to nucleus. Hippocampus is not so complicated as that, but it also has areas with specialized functions. So maybe they messed up the identification of the two genes Bgn and Fmod as drivers of the changes; after all, they found almost 1 000 genes altered by fructose. And that mess-up might have been derived by their blind hypothalamic and hippocampal sampling. EDIT: They didn’t mess up,  per se. Turns out there were technical difficulties of extracting enough nucleic acids from specific parts of hypothalamus for analyses. I told you them nuclei are small…

Anyway, the good news comes from the first experiment, where DHA reverses the bad effects of fructose. Yeay! As a side note, the fructose from corn syrup is metabolized differently than the fructose from fruits. So you are far better off consuming the equivalent amount on fructose from a litre of soda in fruits. And DHA comes either manufactured from algae or extracted from cold-water oceanic fish oils (but not farmed fish, apparently).

If anybody that read the paper has some info that can help clarify my “bothers”, please do so in the Comment section below. The other media outlets covering this paper do not mention anything about the knockouts. Thanks! EDIT: The last author of the paper, Dr. Yang, was very kind and clarified a bit of my “bothers” in the Comments section. Thanks again!

Reference: Meng Q, Ying Z, Noble E, Zhao Y, Agrawal R, Mikhail A, Zhuang Y, Tyagi E, Zhang Q, Lee J-H, Morselli M, Orozco L, Guo W, Kilts TM, Zhu J, Zhang B, Pellegrini M, Xiao X, Young MF, Gomez-Pinilla F, Yang X (2016). Systems Nutrigenomics Reveals Brain Gene Networks Linking Metabolic and Brain Disorders. EBioMedicine, doi: 10.1016/j.ebiom.2016.04.008. Article | FREE fulltext PDF | Supplementals | Science Daily cover | NeuroscienceNews cover

By Neuronicus, 24 April 2016


Stress can kill you and that’s no metaphor

85heart - CopyThe term ‘heartbreak’ is used as a metaphor to describe the intense feeling of loss, sometimes also called emotional pain. But what if the metaphor has roots into something more tangible than a feeling, that of the actual muscular organ giving signs of failure?

Although there have been previous reports that found stress causes cardiovascular problems, including myocardial infarction, Graff et al. (2016) conducted the largest study to date that investigated this link: they had almost 1 million subjects. That’s right, 1 million people (well, actually 974 732). Out of these, almost 20% of them had a partner who died between 1995 and 2014. The chosen stressor was the loss of a loved one because “the loss of a partner is considered one of the most severely stressful life events and is likely to affect most people, independently of coping mechanisms” (p. 1-2). The authors looked at Danish hospital records for people who were diagnosed with atrial fibrillation (AF) for the first time and correlated that data with bereavement information. AF increases the risk of death due to stroke or heart failure.

The people who underwent loss had an increased risk to develop AF for 1 year after the loss. The risk was more pronounced in the first 8-14 days after the loss, the bereaved people having a 90% higher risk of developing AF than non-bereaved people. By the end of the first month the risk had declined, but still was a whooping 41% higher than the average. Only 1 year after the loss the risk of developing AF was similar to that of non-bereaved people.

The risk was even higher in young people or if the death of the partner was unexpected. The authors also looked to see if other variables play a role in the risk, like gender, civil status, education, diabetes, or cardiovascular medication and none influenced the results.

I suspect the number of people that have heart problems after major stress is actually a lot higher because of the under-reporting bias. In other words, not everybody who feels their heart aching would go to the hospital, particularly in the first couple of weeks after losing a loved one.

As for the mechanism, there is some data pointing to some stress hormones (like adrenaline or cortisol) which can damage the heart. Other substances released in abundance during stress and likely to act in concert with the stress hormones are proinflamatory cytokines which also can lead to arrhythmias.

Reference: Graff S, Fenger-Grøn M, Christensen B, Søndergaard Pedersen H, Christensen J, Li J, & Vestergaard M (2016). Long-term risk of atrial fibrillation after the death of a partner. Open Heart, 3: e000367. doi:10.1136/openhrt-2015-000367. Article  | FREE FULTEXT PDF

By Neuronicus, 16 April 2016

Eating high-fat dairy may lower your risk of being overweight

84 - CopyMany people buy low-fat dairy, like 2% milk, in the hopes that ingesting less fat means that they will be less fattier.

Contrary to this popular belief, a new study found that consumption of high-fat dairy lowers the risk of weight gain by 8% in middle-aged and elderly women.

Rautiainen et al. (2016) studied 18 438 women over 45 years old who did not have cancer, diabetes or cardiovascular diseases. They collected data on the women’s weight, eating habits, smoking, alcohol use, physical activity, medical history, hormone use, and vitamin intake for  8 to 17 years. “Total dairy product intake was calculated by summing intake of low-fat dairy products (skim and low-fat milk, sherbet, yogurt, and cottage and ricotta cheeses) and high-fat dairy products (whole milk, cream, sour cream, ice cream, cream cheese, other cheese, and butter)” (p. 980).

At the beginning of the study, all women included in the analyses were normal weight.

Over the course of the study, all women gained some weight, probably as a result of normal aging.

Women who ate more dairy gained less weight than women who didn’t. This finding is due to the high-fat dairy intake; in other words, women who ate high-fat dairy gained less weight compared to the women who consumed low-fat dairy. Skimmed milk seemed to be the worst for weight gain compared to low-fat yogurt.

I did not notice any speculation as to why this may be the case, so I’ll offer one: maybe the people who eat high-fat dairy get more calories from the same amount of food so maybe they eat less overall.

Reference: Rautiainen S, Wang L, Lee IM, Manson JE, Buring JE, & Sesso HD (Apr 2016, Epub 24 Feb 2016). Dairy consumption in association with weight change and risk of becoming overweight or obese in middle-aged and older women: a prospective cohort study. The American Journal of Clinical Nutrition, 103(4): 979-988. doi: 10.3945/ajcn.115.118406. Article | FREE FULLTEXT PDF | SuppData

By Neuronicus, 7 April 2016

The Firsts: the Milky Way’s supermassive black hole

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Let’s wish Happy Birthday to Sir Donald Lynden-Bell, who turns today 81. In 1969 he published a paper where he proposed that massive black holes exist at the center of the galaxies. For this, he was rewarded the Kavli Prize in Astrophysics in 2008.

Before him, in 1951, Piddington & Minnet discovered a radio signal (at 1210 MHz) coming from the nucleus of Milky Way, named Sagittarius A.

Lynden-Bell was proven right in 1974 by astronomers Bruce Balick and Robert Brown who found evidence of Milky Way’s own supermassive black hole. Brown named it Sagittarius A* in 1982 (Sagittarius A* is part of Sagittarius A; and you thought biology nomenclature is confusing…).

Astrophysics terminology aside, happy birthday, Sir Donald!


 1. Lynden-Bell, D (16 Aug 1969). Galactic Nuclei as Collapsed Old Quasars. Nature, 223: 690-694. doi: 10.1038/223690a0. Article  | FULLTEXT PDF

2. Brown, RL (1 Nov 1982). Processing Jets in Sagittarius A: Gas Dynamics in the Central Parsec of the Galaxy. The Astrophysical Journal, 262: 110-119. doi: 10.1086/160401. FULL TEXT

 By Neuronicus, 5 April 2016