Dr. Robert Lustig: How Sugar & Processed Foods Impact Your Health

Dr. Robert Lustig (00:00:00)

• Dr. Robert Lustig is an expert endocrinologist and a professor at UCSF.
• He has authored over 100 peer-reviewed studies on how nutrients affect health.
• Topics discussed include the misconception that "a calorie is just a calorie", the processing of macronutrients, the role of fiber and the gut microbiome, and the addictive properties of sugars, particularly fructose.
• The conversation covered how sugars and fructose can alter hormone function and influence liver, kidney, and overall cellular health.
• The impact of the food industry on dietary habits and cravings was also explored.

Calories, Fiber (00:06:41) and Calories, Protein & Fat, Trans Fats (00:12:15)

• The common belief that weight management is a simple calculation of calories in versus calories out is flawed.
• Almonds example: Consuming 160 calories leads to only absorbing 130 calories due to fiber creating a gel in the intestine, reducing absorption.
• The non-absorbed calories feed the microbiome, producing anti-inflammatory short-chain fatty acids beneficial to health.
• With protein, consuming excess leads to an increased thermic effect, generating more heat as amino acids are deaminated by the liver for ATP production.
• Approximately 25% of energy from protein intake may not be counted towards total caloric intake because of its thermogenic properties.
• Different fats impact health differently—omega-3s are vital and protective, while trans fats are harmful and can lead to chronic diseases.
• The conversation underscores that not all calories are equal in how they impact the body due to differential digestion, absorption, and metabolism.

Carbohydrate Calories, Glucose vs. Fructose, Fruit, Processed Foods (00:18:23)

• Glucose is essential for life, used by every cell for energy, and if not consumed, the body can produce it from other substances like amino acids or fatty acids.
• The body requires a constant glucose level for brain and heart function, as well as structural roles in proteins and hormones, with aging potentially affecting hormone glycosylation.
• Fructose, unlike glucose, is non-essential and no vertebrate requires dietary fructose for biochemical processes.
• High consumption of fructose is addictive and has increased 25 times since the last century, with significant amounts added to processed foods, thus impacting health.
• Fruits like berries, which are high in fiber and low in fructose, are healthier compared to high fructose foods without fiber, such as soft drinks.
• Fiber in fruit mitigates the absorption of fructose and is beneficial for the microbiome, making whole fruits a better option than processed foods.

Fructose, Mitochondria & Metabolic Health (00:26:43)

• Fructose inhibits three key enzymes necessary for normal mitochondrial function, which is essential for metabolic health.
• Inhibitions include AMP kinase (important for mitochondrial biogenesis), Acyl-CoA dehydrogenase (for fatty acid metabolism), and Carnitine palmitoyltransferase 1 (for fatty acid shuttling into mitochondria).
• The potency of fructose inhibition varies based on dose, with chronic intake posing significant health issues.
• Long-term consumption of ultra-processed food with high sugar content correlates with decreased lifespan in America; an "8-year longevity tax" for average citizens and even more for those with metabolic syndrome or obesity.

Trans Fats; Food Industry & Language (00:31:54)

• Omega-6 and trans fats have been problematic for health, but trans fats are now banned from the food supply.
• Trans fats used to be considered part of a standard diet, like margarine, but are now understood to be detrimental to health, particularly to liver function.
• Sugar has now become the primary health concern due to its inhibiting effect on three key enzymes related to mitochondrial function.
• There is a significant problem with the language used in nutrition; for instance, the oversimplification of terms like "fat" and "calories" have caused confusion and misinformation.
• The food industry has deliberately exploited this confusion by spreading misleading information about sugar, calories, and fats.

Glucose, Insulin, Muscle (00:37:04)

• The metabolism of carbohydrates, particularly glucose, affects energy expenditure, the thermic effect of food, and physical activity energy requirements.
• Consuming glucose causes a spike in blood sugar levels, which is then regulated by insulin to normalize these levels.
• While insulin is essential for lowering high blood glucose, it also promotes the storage of excess energy as fat.
• Insulin's action is immediate, and within about 90 minutes, excess glucose is stored as fat if not used by the muscles during physical activity.
• Muscles can take up glucose without insulin for immediate energy and glycogen storage; however, in absence of exercise, excess glucose results in an insulin response and fat storage.

Insulin & Cell Growth vs. Burn; Oxygen & Cell Growth, Cancer (00:42:31)

• Insulin plays a significant role in metabolic disease as demonstrated by research on the PODIR KO (tissue-specific insulin receptor knockout) mouse.
• This mouse model, with insulin receptors specifically knocked out in the kidney glomular cells, remains normoglycemic with normal glucose tolerance and insulin levels, but develops severe diabetic nephropathy without actual diabetes.
• The worsening kidney condition in these mice indicates that it is insulin, not glucose, causing the damage, even in the absence of high blood sugar levels.
• Insulin is identified as a driver of cell growth; every cell in the body has the ability to burn (metabolize) or grow, and these processes are influenced by oxygen availability.
• The presence of oxygen guides cells towards burning for energy, while a lack of oxygen pushes cells towards growth.
• Otto Warburg won a Nobel Prize for discovering that cancer cells do not need oxygen to grow, which is also true for all cells; oxygen rather inhibits growth.
• The article "Mount Everest in utero" from the New England Journal of Medicine (1951) connects fetal development with low oxygen levels, as the partial pressure of oxygen in the placenta is significantly lower than atmospheric levels, enabling rapid cell growth.
• Post-birth, oxygen levels increase when the baby starts breathing on its own, causing cell growth rates to slow down.
• Hyperbaric oxygen therapy as a treatment for tumors has been discussed, leveraging the concept of increasing oxygenation to potentially inhibit tumor growth.
• The overall discussion links back to the impact of insulin and the role of oxygen in cell growth and metabolism, with implications for dietary intake and its effect on health, specifically through mechanisms like the example of glucose excursions from bagel consumption driving lipid synthesis and cell growth in the absence of sufficient oxygen.

Glucose vs. Fructose, Uric Acid; “Leaky Gut” & Inflammation (00:51:14)

• Consuming glucose involves a metabolic process that generates uric acid, which can inhibit mitochondrial function and reduce nitric oxide, raising blood pressure.
• Fructose can exacerbate leaky gut by compromising the integrity of tight junction proteins in the intestine, leading to inflammation and systemic health issues.
• 250 calories of glucose from a source like a bagel is metabolized differently than an equivalent calorie intake from fructose as found in sugary drinks and cookies.
• The liver processes fructose differently, potentially converting it into triglycerides, which can contribute to cardiovascular disease.
• The conversation explores the distinction between glucose and fructose regarding their different effects on the body, illustrating that not all calories are metabolized identically.

Supporting the Gut Microbiome, Fasting (01:00:51)

• The gut microbiome requires fiber from one's diet to maintain the mucus layer that acts as a barrier to protect intestinal tight junctions.
• If the microbiome is deprived of necessary nutrients, it can consume the body's intestinal lining.
• Intermittent fasting, when followed with the consumption of fiber-rich and fermented low-sugar foods, has the potential to replenish and support the gut microbiome and intestinal lining more effectively than constant feeding.
• The discussion sheds light on the importance of dietary fiber and fermented foods in maintaining good gut health and the impact of fasting on the gut microbiome.

Highly Processed Foods, Sugars; “Price Elasticity” & Food Industry (01:04:13)

• Highly processed foods provide calories with little nutritional value, contribute to leaky gut, and lack beneficial antioxidants
• Consuming some sugar in moderation, as in dessert, is acceptable, but it should not be a staple in breakfast, lunch, or snacks
• The National School Breakfast Program often serves food with high sugar content, exceeding recommended limits for children
• Ingredients in seemingly healthier breakfast options, like Honey Nut Cheerios or homemade waffles, often contain high sugar levels
• The food industry uses sugar to increase product desirability because it knows sugar is addictive
• Price elasticity in economics shows the relationship between the price increase and consumption decrease – eggs are highly price elastic
• Fast food, soft drinks, and juice are among the most price inelastic foods, indicating people will continue to buy them despite price increases due to sugar addiction
• The concept of the hedonic (pleasure-seeking) actor in economics, who disregards cost in pursuit of a fix, applies to those addicted to sugar

Processed Foods & Added Sugars (01:11:51)

• Common breakfast cereals are often loaded with sugars, despite being advertised as healthy
• American bread often contains added sugars to extend shelf life and resist staling, unlike European bread, which is less sweet and stales quickly
• Store-bought bread uses sugar to maintain sponginess and moisture through a phenomenon known as water activity
• Even staple foods like bread are being augmented with sugar, leading to chronic metabolic diseases

Sugars, High-Fructose Corn Syrup (01:14:19)

• Sugar is comprised of glucose and fructose; table sugar (sucrose) contains one molecule of each, bound together
• Sucrose, broken down by the enzyme sucrase upon ingestion, is metabolized with fructose going to the liver and glucose to the body
• High-fructose corn syrup consists of free glucose and fructose molecules, making it metabolically indistinguishable but cheaper than sucrose
• High-fructose corn syrup is utilized differently than sucrose in the food industry, owing to economic reasons and its liquid form, enabling higher doses in products like cookies

Food Industry & Added Sugar, Personal Responsibility, Public Health (01:18:16)

• Dr. Lustig asserts that while there are good and bad actors in the food industry, there is a deliberate effort to lace food with sugar, driving cravings and contributing to metabolic illness.
• According to Dr. Lustig, food industry's focus on profits leads to public health issues, as personal responsibility in dietary choices is ineffective without societal intervention.
• Personal responsibility requires four criteria: knowledge, access to healthy alternatives, affordability, and no harmful externalities to others.
• Knowledge is often withheld from the public, keeping them unaware of the risks associated with processed foods and added sugars.
• Access is limited for those in food deserts or swamps, where unhealthy options are prevalent.
• Affordability encompasses both an individual's ability to purchase healthy foods and society's ability to bear the healthcare costs associated with poor diet choices.
• Externalities from one's dietary choices should not negatively impact others, yet healthcare costs related to obesity impact everyone financially.
• Dr. Lustig highlights that the governmental separation of food industry profits from healthcare costs obscures the financial burden created by managing health issues born from poor diets.
• He suggests that the true cost includes the food industry's profits offset by the global costs of healthcare and productivity losses, which create a significant deficit.
• Despite understanding the statistics and costs, daily decision-making at the consumer level is disconnected from these broader financial and health impacts due to a disconnect in immediate consequences.
• Governmental measures are necessary to bridge the gap between understanding the impact of food choices and actually making healthier decisions at the point of purchase.

Obesity, Diabetes, “Hidden” Sugars (01:30:04)

• Obesity and diabetes are major health issues, with diabetes affecting 11.4% of Americans, up from 8% two decades ago.
• The increase in diabetes is attributed to higher sugar intake and hidden sugars in processed foods.
• Countries like Pakistan, India, and China with high diabetes rates despite lower obesity is due to ultra-processed foods.
• Many countries, especially in Europe, do not allow high fructose corn syrup (HFCS).
• However, countries without HFCS, like Australia and Thailand, still face obesity and diabetes issues because sucrose has the same metabolic effect.
• The definition of food should involve contribution to growth or energy burning.
• Ultra-processed foods are considered "consumable poison" because they inhibit mitochondrial function and growth, leading to adverse health effects.

Diet, Insulin & Sugars (01:34:57)

• Weight loss in middle-aged individuals has been achieved through diets excluding starches, alcohol, and soda while maintaining high levels of exercise.
• Elimination of processed foods and liquid calories helps in shedding significant weight.
• The crucial factor for weight loss is lowering insulin rather than calorie reduction.
• Insulin promotes energy storage in fat cells, preventing weight loss.
• Reducing intake of refined carbohydrates and sugar and certain Branch Chain Amino Acids (BCAAs) helps lower insulin levels.

Tools: NOVA Food Classification; Perfact Recommendations (01:38:20)

• The NOVA food classification system categorizes foods by processing level, associating 'ultra processed' (Class 4) foods with chronic metabolic diseases.
• A small percentage (7-10%) of daily calories from NOVA Class 4 foods is acceptable.
• There's a web-based tool called Perfact, which is a recommendation engine based on metabolism rather than nutrient content.
• It filters out NOVA Class 4 foods, encouraging consumption of NOVA Class 1-3 foods, which are healthier.
• The tool suggests maintaining a low insulin level by avoiding refined carbs and sugar, increasing fiber, and selecting proteins low in BCAAs.

Meat & Metabolic Health, Eggs, Fish (01:43:46)

• Grass-fed meat, like in Argentina and New Zealand, is tougher than marbled (corn-fed) meat but is healthier for metabolic health.
• Marbling in meat indicates intramyocellular lipid and metabolic syndrome in the animal.
• American corn-fed animals consume branch chain amino acids which can lead to health issues like fatty liver disease and insulin resistance.
• Eggs have a near-perfect protein score and are a good food choice; the color of the yolk can indicate omega-3 content.

Sources of Omega-3s; Vitamin C & Vitamin D (01:46:44)

• Main sources of omega-3 fatty acids include fish, ALA from vegetables, EPA from marine life, and DHA from marine life or algae.
• The speaker takes fish oil, vitamin C for rosacea, and vitamin D as supplements.
• Vitamin D supplementation does not cure associated chronic diseases, which may be linked to high sugar and processed soft drink intake.
• Inflammation can prevent the effective metabolism of Vitamin D from its inactive form to its active form, rendering supplementation ineffective for many.

Tool: Reduce Inflammation; Sugars, Cortisol & Stress (01:52:37)

• Reducing fructose intake is effective in reducing systemic inflammation alongside minimizing oxidative stress.
• Lifestyle improvements such as increased fiber intake and better sleep can reduce inflammation.
• Chronic elevation in cortisol can lead to inflammation, though acute cortisol response is necessary and beneficial for managing stress.
• The prevalence of obesity, especially in children and adults, has significantly increased in the US.
• Factors like altitude and cold can increase mitochondrial biogenesis and potentially reduce obesity.
• Lifestyle elements like light exposure, cold therapy, food, and movement can be utilized to adjust physiology with little cost.

Food Industry, Big Pharma & Government; Statins (01:59:12)

• Food industry influences government through financial contributions to political campaigns.
• American Legislative Exchange Council (ALEC) is criticized for writing bills in favor of their funders, including big food and pharma industries.
• Dr. Robert Lustig argues statins are overprescribed and actual benefits for primary prevention are minimal, citing four days increase in lifespan.
• Higher LDL cholesterol levels may not be as harmful as once believed, with dietary fat affecting "large buoyant" LDL which is cardiovascularly neutral, unlike "small dense" LDL.
• Reduction of small dense LDL, strongly associated with cardiovascular risk, is best achieved by reducing sugar intake, as it correlates with liver output of triglycerides.
• Big Pharma and Food are aware of these facts but continue with current practices due to financial interests in statins and processed foods.

Public Health Shifts, Rebellion, Sugar Tax, Hidden Sugars (02:06:55)

• The current U.S. food management system is broken with 51 different federal agencies causing inefficiency.
• Anti-smoking campaigns succeeded by tapping into the rebellious nature of youth, suggesting a model for tackling sugar addiction.
• Berkeley's soda tax exemplifies a successful public health intervention leading to reductions in gestational diabetes, obesity, and cardiovascular disease.
• Four public health shifts in America were accomplished by educating children who grew into socially responsible adults while opponents aged out; examples include seat belt usage, smoking in public places, drunk driving awareness, and condom availability.

Real Food Movement, Public School Lunches & Processed Foods (02:12:58)

• There is a growing Real Food Movement advocating against ultra-processed foods.
• Public schools serve as the biggest fast food franchise in the United States when it comes to providing meals to children.
• The 'Eat Real' non-profit organization is working on establishing a business model for public schools to improve food quality.
• In 1971, under Nixon's administration, public school cafeterias were mandated by Resolution 242 to be financially self-sufficient, leading to partnerships with food companies.
• These companies provided meals that were not genuinely nutritious and enabled schools to convert food preparation spaces into classrooms.
• The shift towards external management of school meals resulted in schools being dependent on the food industry.
• Over time, the quality of school food has increasingly comprised commoditized items with long shelf life, aligning with interests of major food suppliers.
• Currently, children are experiencing high rates of obesity, poor academic performance, and depression, partially due to poor diet and excessive consumption of ultra-processed foods.

3 Fat Types & Metabolic Health; Sugar, Alcohol & Stress (02:18:25)

• Body fat is categorized into three distinct types: subcutaneous, visceral, and liver fat, all differing metabolically.
• Roughly 22 lbs of subcutaneous fat can be gained before metabolic issues arise because it drains into systemic circulation and has a larger volume distribution.
• Compared to muscle cells, fat cells release pro-inflammatory cytokines when they become necrotic due to overstuffed fat vacuoles, leading to inflammation.
• Visceral fat, associated with stress and cortisol, is more harmful; only about 5 lbs need to be accumulated to cause metabolic problems because it drains directly to the liver.
• The liver can store only about half a pound of fat before metabolic dysfunction occurs, with excess fat primarily coming from alcohol or sugar consumption, both of which are addictive.
• Eliminating alcohol and sugar can reduce liver fat, and intermittent fasting can help the liver offload stored fat.
• Mitigating stress is challenging, impacting visceral fat accumulation, while subcutaneous fat, although aesthetically concerning for some, is metabolically the least harmful.

Artificial & Non-Caloric Sweeteners, Insulin & Weight Gain (02:26:40)

• Artificial and non-caloric sweeteners, including aspartame, sucralose, Stevia, monk fruit, and aloes, do not reduce body fat as expected.
• Despite lower calorie intake, dieters consuming diet sodas with sweeteners like aspartame or Stevia may still gain weight due to an insulin response.
• A study in Copenhagen showed that individuals consuming one liter of diet soda daily for six months gained weight, whereas those drinking sugared soda gained more, and water drinkers lost weight, suggesting that artificial sweeteners could lead to increased hunger and weight gain.
• Another study by Dana Small demonstrated that the insulin response from diet soda coupled with food could lead to a compounded effect on weight gain.
• Further research in Singapore found that individuals consuming diet sweeteners consumed more food at subsequent meals and exhibited increased insulin responses.

Re-Engineering Ultra-Processed Food (02:34:32)

• Dr. Robert Lustig was approached by Kuwaiti Danish Dairy Company (KDD) to help them become a metabolically healthy food company.
• Kuwait has a high rate of diabetes (18%) and obesity (80%).
• Lustig put together a scientific advisory team and began a project to re-engineer KDD's food products according to three health principles: protect the liver, feed the gut, and support the brain.
• To create metabolically healthy products, the guidelines included reducing sugar content, adding fiber and Omega-3 fatty acids, and addressing the issue of emulsifiers causing gut inflammation.
• KDD's significant effort included biochemically analyzing all ingredients and resulted in 10% of their products becoming metabolically healthy, following a strategy outlined in a paper published in Frontiers in Nutrition, March 2023.

Sugar & Addiction, Caffeine (02:38:45)

• Foods not marketed as diet foods often contain non-caloric sweeteners like sucralose to drive cravings through insulin increases.
• Insulin blocks leptin signaling in the brain, making a person hungrier and preventing satiety from stopping food cravings, similar to being an automaton.
• Dopamine stimulates neurons but chronic overstimulation can lead to neuronal cell death.
• Neurons respond by downregulating dopamine receptors to protect against overstimulation, leading to tolerance and potentially addiction.
• Fat is not considered addictive because ketogenic or Atkins diet followers would otherwise gain weight, not lose it.
• Data suggest that low-calorie sweeteners, like Stevia, are not beneficial for health, but fats, salts, and caffeine are not the primary problems.
• Caffeine is an addictive substance, yet no evidence shows it is toxic in coffee form without excess.
• Adding caffeine to foods, like plain yogurt, can increase cravings for those foods due to the desirable effects of caffeine.
• While caffeine is highly reinforcing, it is acceptable to continue consuming it as long as it doesn't cause anxiety or excess energy.

GLP-1, Semaglutide (Ozempic, Wegovy, Tirzepatide), Risks; Big Pharma (02:45:18)

• GLP-1 agonists, such as semaglutide, are based on a hormone initially found in the Gila monster that promotes satiety.
• The primary function of GLP-1 is to slow gastric emptying, keeping individuals full longer.
• In South America, yerba mate is consumed for its laxative effect, which may impact satiety through modestly increasing GLP-1.
• GLP-1 analogues like semaglutide and tirzepatide are expensive, costing around $1,300 monthly but are effective in weight loss.
• A significant portion of the weight loss from GLP-1 analogues can come from muscle mass, which is an undesirable outcome.
• After one year of treatment with these GLP-1 analogues, patients can experience 16% weight loss but lose both fat and muscle.
• Weight loss through medication can lead to severe side effects such as nausea, vomiting, and in some cases, gastroparesis.
• Some patients also report a reduction in alcohol cravings and instances of major depressive disorder, highlighting the drugs' effects on the brain’s reward system.
• Weight loss drugs have a history of severe adverse events, including depression and suicide, as seen with the European weight loss drug rimonabant.
• The use of GLP-1 analogues could potentially lead to a large increase in healthcare costs if widely adopted.
• Dr. Lustig suggests that reducing sugar consumption to within USDA guidelines could result in greater weight loss and significant healthcare savings.
• The conversation then touches on the influence of government and industry relationships that could benefit from the sale of these drugs, despite potential cost-saving alternatives.
• While the drugs possess clear downsides, Dr. Lustig acknowledges their usefulness for the right patients, contrasting the current situation with that of statins, where he feels they may be overprescribed.

Obesity & Sugar Addiction; Brain Re-Mapping, Insulin & Leptin Resistance (02:57:39)

• Engaging in resistance training can help maintain muscle mass, which is important, especially for those on medication that can cause muscle loss.
• Drinking less alcohol is being observed, but the issue with obesity and associated health problems persists due to sugar addiction.
• Some overweight individuals may need a "jump start" to lose weight, such as through stomach stapling, but this is often not effective in the long term, especially for sugar addicts.
• Excessive weight leads to remapping of the brain, making healthy weight loss increasingly difficult due to changes in neural circuitry.
• Obesity is linked to leptin and insulin resistance, with leptin being a hormone that signals satiety to the brain.
• High insulin levels block leptin signaling, promoting hunger and reduced energy expenditure.

Fructose & Addiction, Personal Responsibility & Tobacco (03:03:31)

• Fructose activates neurons in the reward pathway more significantly than glucose, which can lead to addiction.
• Chemical addictions such as those to fructose are similar to addictions to drugs like heroin, cocaine, and nicotine.
• The concept of personal responsibility in addiction clashes with the understanding that addiction may impair an individual's ability to seek treatment.
• The tobacco industry coined the term 'personal responsibility' to shift focus away from the addictive properties of tobacco and onto the consumer's choices.

Food Choices: Fruit, Rice, Tomato Sauce, Bread, Meats, Fermented Foods (03:07:27)

• Whole fruit is acceptable due to its fiber content, while fruit juice is not due to the lack of fiber.
• Opt for brown rice over white rice due to the beneficial fiber content in brown rice.
• Many commercial tomato sauces contain added sugar; consumers must be selective and can use resources like perfect to find suitable options without added sugar.
• Sourdough and high-fiber bread are better choices due to the fermentation process and lower carbohydrate-to-fiber ratios.
• Meat, fish, and eggs consumption depends on their source, with organic, pasture-raised, and antibiotic-free options being preferable.
• Low sugar fermented foods are beneficial due to the production of short-chain fatty acids, with kimchi and live sauerkraut being good options while caution is advised with commercial yogurts as they may contain dead cultures and added sugar.

Intermittent Fasting, Diet Soda, Food Combinations, Fiber, Food Labels (03:12:54)

• Intermittent fasting benefits patients with liver fat by allowing the liver to burn off stored fat.
• Zero-calorie and sugary sodas are both unhealthy; sugary sodas are likened to "poison in a can."
• Combining sugary foods with fat can blunt insulin response, but combining with fiber is more beneficial.
• Dr. Lustig is the chief medical officer for a company, BioLumina, that produces a proprietary fiber called Munch Munch.
• Munch Munch expands in the stomach, creating a sense of fullness, delaying sugar absorption, and feeding gut microbiota.
• Fiber supplements are useful, but a combination of soluble and insoluble fiber is necessary.
• Nova class 1 foods are unprocessed, without a label, and the healthiest option.

Improving Health, Advocacy, School Lunches, Hidden Sugars (03:19:14)

• To improve health, eliminate sugar intake and engage in regular physical activity like walking.
• Advocacy efforts could target policy changes and awareness at schools and hospitals to promote healthy eating.
• UCSF's Healthy Beverage Initiative eliminated sugary sodas from their campus.
• To address school lunches, a model where meals are prepared from scratch and distributed across schools could improve children's nutrition.
• Sugars are often hidden on ingredient lists under various names; look for "added sugars" to identify unhealthy content.
• Aim for <4 grams of added sugars per serving, and prefer Nova classes 1, 2, and 3 foods.
• Dr. Lustig emphasizes the importance of understanding science and science communication in the context of public health.