Dr. Robert Lustig’s YouTube lectures about the dangers of sugar have raised a few eyebrows in recent years and even drawn some criticism.

But the pediatric endocrinologist’s proclamations are supported by research his team has done at the University of California, San Francisco, with steady confirmation from other scientific studies linking sugar with chronic disease and early death. Among his points are:

1. Sugar is poison.

2. Sugar is sugar and unhealthy in any form.

3. A calorie is not just a calorie. There are good ones and bad ones, including sugar.

4. Obesity is not a prerequisite for metabolic illness. Eighty percent of those with obesity do have metabolic disease or resulting chronic illness. But 40 percent of people of normal weight also have such diseases.

5. And don’t blame those who are obese or chronically ill for their conditions. It’s not so much poor lifestyle behavior as it is biochemical exposures to sugar and other unhealthful ingredients that food manufacturers routinely put into food products, with consumers often being unaware.

As Prevention magazine says, “If it’s packaged, it’s probably packed with sugar.”

Lustig’s latest YouTube video, “Fat Chance: Fructose 2.0,” has received 155,000 views and climbing. But his 2009 YouTube lecture, “Sugar: the Bitter Truth,” which details the biological consequences of high fructose corn syrup, is approaching 4.5 million views. He also has two books on the topic.

But he defers to Will Smith — as Agent J in “Men in Black 3” — to answer the question Agent K (Tommy Lee Jones) asks: “What’s the most destructive force in the universe?”

“Sugar?” Agent J says, with an inquisitive lilt.

“He got it right. We know these substances are addictive and hazardous to health,” Lustig said, leading to an audience scold. “Hollywood knows this. Why don’t you?”

By any other name

Sugar is listed in Nutrition Facts food labels by 56 names, including various malts and syrups. Most people might be unaware that dextran, athyl maltol, treacle, panocha, lactose and sorbitol also are names for sugar.

Fructose is drawing attention with the increased use of high fructose corn syrup in foods, especially in soft drinks. The sweetener produced chemically from corn starch provides better texture and improves shelf life.

Sucrose, or table sugar, is half fructose, which is metabolized in the liver, and glucose, which is blood sugar that produces cellular energy to muscles and organs.

In the liver, excess fructose is transformed into fat, which can be a factor in elevated cholesterol and arterial plaque. High fructose corn syrup used in soft drinks has a 55-45 ratio of fructose to glucose.

Lustig says sugar is addictive, although not everyone agrees. Some researchers link high consumption rates to its overabundant availability in American culture and diet.

A recent study by Lustig’s team concludes that 25 percent of type 2 diabetes is caused specifically by sugar consumption.

Studies also conclude that sugar consumption leads to fatty liver, high triglyceride and bad LDL cholesterol levels, plaque in blood vessels and insulin resistance leading to metabolic syndrome and diabetes.

“There definitely are a number of studies that show within big populations a big relationship between sugar consumption and every metabolic disease we have — diabetes, cardiovascular disease, metabolic syndrome, fatty liver, hypertension and particular risk factors of (high cholesterol and triglycerides),” said Kimber Stanhope, a University of California, Davis, nutritional biologist.

“These studies, along with evidence from diet-intervention studies in which we compare risk factors in human subjects consuming high- or low-sugar diets, suggest that consumption of high amounts of sugar promotes metabolic disease,” she said.

In February, a study published in the journal JAMA Internal Medicine found that “most United States adults consume more added sugar than is recommended for a healthy diet,” with findings of “a significant relationship between added sugar consumption and increased risk for cardiovascular disease mortality.”

Those whose added sugar consumption was more than 10 percent but below 25 percent of total daily calories face a 30 percent higher risk of cardiovascular disease than those whose sugar consumption was less than 10 percent. The risk of cardiovascular disease nearly tripled for those whose diet consisted of 25 percent or more of added sugar.

The study said findings were largely consistent across age groups, gender, race or ethnicity (except for non-Hispanic African-Americans), education level, physical activity and body mass index. “Our results support current recommendations to limit the intake of calories from added sugars in U.S. diets,” it concludes.

The American Heart Association recommends fewer than 100 calories of sugar daily for women and 150 calories a day for men — about 5 percent or less of total daily calories.

New Nutrition Facts labels proposed by the U.S. Food and Drug Administration, expected to be in place in two years, would require companies to continue listing total sugar but also “added sugar” to help people differentiate between naturally occurring sugar in grains, nuts, fruits and vegetables from those added by the manufacturer to enhance taste, texture or shelf life.

Path to disease

High fructose corn syrup is used in numerous processed foods, including soft drinks such as Coca-Cola and Pepsi.

Fructose in fruit isn’t considered a health risk because levels are so low, because the fruit fiber slows the rate of metabolism. Sucrose comprises equal amounts of glucose and fructose. Too much of it overwhelms the liver, which causes the liver to start turning some of the fructose into fat, Stanhope said.

“Fat can stay in the liver, which may interfere with the liver’s ability to use insulin properly,” Stanhope said. “This is called insulin resistance, and it increases risk for diabetes and cardiovascular disease. Or the liver can send the fat made from fructose into the blood stream where it can increase risk of cardiovascular disease.”

The process is compounded by America’s high consumption of foods full of fat and sugar.

Claims, counterclaims

While research likely will never provide absolute proof of sugar’s impact on human health, population studies reveal a close association between sugar consumption and metabolic disease. That among growing evidence from diet intervention studies raise red flags about its harm, much the way the health impacts of cigarette smoking were determined, Stanhope said.

In his latest video, Lustig noted that “old medicine” recognized infection as the main cause of disease with the vector being the various microbes — viruses, bacteria and fungi. Nowadays, he says, medicine must focus on chronic disease with the vector being “multinational corporations,” if we place the blame on food manufacturing and marketing.

Because of the lack of direct evidence Stanhope referred to, food companies maintain there is no proof that consuming sugar causes a person to be more likely to get sick.

But Stanhope, who consumes sugar only on special occasions (about once a month) said evidence is more than sufficient to advise people against its consumption.