This one caught my eye today.
If you pick up any packet of cereal you find it is enriched with vitamins:
Ingredients
Maize, Brown Sugar (Sugar, Molasses), Peanuts (7%), Sugar, Honey (2%), Barley Malt Flavouring, Salt, Niacin, Iron, Vitamin B6, Riboflavin (B2), Thiamin (B1), Folic Acid, Vitamin B12.
Some Chinese scientists have just done a study indicating that Niacin can mess up insulin sensitivity....and make you fat
A research team from China examined the role of excess nicotinamide in glucose metabolism using co-loading of glucose and nicotinamide test. They proved that excess niacin intake-induced biphasic response, i.e., insulin resistance in the early phase and hypoglycemia in the late phase, may be a primary cause for the increased appetite in obesity. Their study will be published on May 21, 2010 in the World Journal of Gastroenterology.I've not been able to access the full article yet but I certainly think there are some interesting implications there. Especially the last bit - exercise and sweating is healthy too in that it gets rid of excess niacin.
The study also revealed for the first time that the obesity prevalence among US children and adolescents increased in parallel with the increase of the per capita niacin consumption with a 10-year lag, in which niacin fortification-induced sharp increase in niacin contents in grain products may play a major role. Reducing niacin intake and facilitating niacin elimination through sweat-inducing physical activity may be a key factor in the prevention and treatment of obesity.
Comments
The increase in grain consumption seems more likely to be the primary cause. Culture have gotten fat for a long time when white flour and sugar were introduced, and certainly those were not fortified until very recently.
There are a lot of these factors being unearthed, and they probably all contribute to some degree.
But I have to see that it's really kind of convoluted to attribute the problem to the tiny bit of niacin with which the grains are fortified. To my mind, that's because they just can't bring themselves to say that the grains themselves are the problem.
At least this one wasn't funded by the U.S. taxpayers. I would be pissed.
I wonder how much it would cost the U.S. taxpayers if we stopped subsizing wheat and corn and actually went to sustainable fruit/vegetable/livestock farms.
By the way, unlike some of the other commentators, I do not assume all scientists, especially those with whom I disagree, are idiots who make fundamental errors in their experimental methodology, or who are stooges of industry. I'm sure that Chinese science is aware that too much sugar makes you fat.
Positive Massage Therapy
The problem isn't just the researchers. It's also the higher educational systems failing to teach them adequately how to make fundamentally sound experiments.
Considering the amount of bad experiments in exercise and nutritional science, this is a systemic issue that needs to be addressed whether it is the researchers themselves, the journals which publish the studies, or the educational institutions that are producing such research.
Criticism is due where it's due. You become jaded about it after a while.
Full text here
The idea of a biphasic response of insulin sensitivity to niacin is at least 14 years old.
The mechanism of insulin resistance from niacin administration may also differ from resistance due to chronic excess carbohydrate consumption.
Insulin resistance in adipocytes after downregulation of Gi subtypes
Nicotinic acid-induced insulin resistance is related to increased circulating fatty acids and fat oxidation but not muscle lipid content
The nicotinic acid receptor--a new mechanism for an old drug.
The authors also don't discuss the role phosphorus metabolism may have in niacin based insulin resistance (6 years old).
Are the effects of nicotinic acid on insulin resistance precipitated by abnormal phosphorous metabolism?
Hypophosphataemia: cause of the disturbed metabolism in the metabolic syndrome.
Hypophosphataemia in the metabolic syndrome. Gender differences in body weight and blood glucose
As the higher insulin levels also correspond with an decrease in the time to return to basal glucose levels (figure 2), the observed effect may be neutral or positive by reducing the mean duration of elevated plasma glucose, and subsequently HbA1c levels.
This may be consistent with a few papers I've reviewed on the use of niacin in diabetics, with HbA1c levels remaining relatively unchanged.
Niacin treatment of the atherogenic lipid profile and Lp(a) in diabetes
Effect of Niacin on Lipid and Lipoprotein Levels and Glycemic Control in Patients With Diabetes and Peripheral Arterial Disease
The discussion of this paper is the worst part.
"The major findings of this study are: (1) nicotinamide overload may induce a biphasic effect on glucose metabolism, characterized by insulin resistance followed by hypoglycemia; and (2) there is a significant association between the US per capita niacin consumption and the obesity prevalence in US children and adolescents..."
The biphasic effect was previously established with much larger sample sizes than the current study (n=5)
The hypoglycemic response to high dose niacin was noted as far back as 19 year ago, and seems to be limited to patients with established glucose intolerance.
Niacin revisited: clinical observations on an important but underutilized drug.
Also note, that on average these subjects all fail the OGTT (figure 2), as without niacin they appear to be > 6.1 mmol/L at 2 hours, which meets the WHO's 1999 Diabetes Guidelines for impaired fasting glycemia.
"These findings may help explain both the development of obesity and the increased prevalence of obesity."
Right.
What do the authors want to be true?