10 Medical Studies That Prove Good Nutrition is No Joke

Illustration by Daniel Downey Jr.

Illustration by Daniel Downey Jr.

By Maureen Salamon

When it’s time for a meal, who do we usually eat with? Family or friends, of course. But while our loved ones make fine dinner companions, unfortunately they’re not usually the most reliable source of accurate information about what should actually make it into our diets. And it’s increasingly obvious that we often just don’t know where to turn for solid advice about good nutrition.

A recent article in the Wall Street Journal revealed that 8 in 10 Americans feel there’s so much conflicting information out there about what they should eat – or not eat – that they routinely second-guess their food choices. “To varying degrees, we listen to advice from not just experienced nutrition professionals, but also from health coaches, personal trainers, social media, bloggers, television, government agencies and food companies,” the article said. “Is our inability to determine the best, most reliable sources of information getting in the way of the improved health we almost universally seek?”

But hard science rarely lets us down. Here are 10 medical studies that cut through the confusion and prove good nutrition is no joke. What do they tell us?

1. All Calories Aren’t Equal    

The argument has long been made that maintaining weight simply means calories in must equal calories out – regardless of food choices. But a 2010 study in Food & Nutrition Research upends that notion, finding that volunteers burned almost twice as many calories to break down a sandwich made with cheddar cheese on multigrain bread than one made with white bread and processed cheese. Why? Because our bodies actually expend more energy digesting nutritionally superior unprocessed carbs.

2. No single diet is best for health    

The dizzying number of articles and books comparing one diet to another – we’re looking at you, Mediterranean, low carb, low fat, Paleo and other popular diets – try to convince us that one is best for our health. But that’s just not true. According to a 2014 paper in the Annual Review of Public Health by nutrition stalwart Dr. David Katz, eating foods closest to their natural form – regardless of what diet plan they fall under – is what really matters. “A diet of minimally processed foods close to nature, predominantly plants, is decisively associated with health promotion and disease prevention and is consistent with the salient components of seemingly distinct dietary approaches,” he wrote.

3. Good nutrition really can prevent cancer  

The idea of an anti-cancer diet is widely touted, and an estimated 30% to 40% of all malignancies can be prevented through diet and lifestyle alone. But exactly what nutrients do we need to aim for to up our odds of avoiding cancer? A 2004 evidence review in Nutrition Journal lists “protective elements” such as selenium, folic acid, vitamin B-12, vitamin D, chlorophyll, and antioxidants, along with supplementary oral digestive enzymes and probiotics. A diet that includes these nutrients is likely to contribute to a 60% to 70% decrease in breast, colorectal and prostate cancers, and even a 40% to 50% decrease in lung cancer, the research said. 

4. Heart-healthy eating habits start young    

Systemic inflammation has long been known to contribute to coronary artery disease, upping our risk of suffering a heart attack or stroke. But fruits and vegetables, which are high in flavonoids and antioxidants, not only lower inflammation levels in adults, but in adolescents as well – setting them up for a heart-healthy life. According to a 2009 study in the Journal of the American Dietetic Association, markers of inflammation and so-called “oxidative stress” – an imbalance of dangerous free radicals in the circulation – were lower in 285 boys and girls ages 13 to 17 whose diets were higher in fruits and vegetables.

5. Sugar-laden diets raise risk of dying of heart disease  

Don’t just pay attention to saturated fats if you’re aiming to avoid heart disease. Even if you’re not overweight, eating too much added sugar makes it far more likely you’ll die of heart disease, according to a 2014 study in JAMA Internal Medicine. Over 15 years of tracking tens of thousands of people, researchers found that those who consumed 25% or more of their daily calories as sugar were more than twice as likely to die from heart disease as those whose diets were comprised of less than 10% of added sugar. And sugar-sweetened drinks such as soda, energy drinks and sports drinks are mostly to blame, researchers said.

6. Got psoriasis? Add or reduce these foods  

More than 7.5 million Americans cope with “the heartbreak of psoriasis,” a chronic inflammatory disease causing silvery, red plaques to form on the skin and even cause arthritis. But a national survey of psoriasis patients in the June 2017 issue of Dermatology and Therapy pinpointed which dietary changes improved their skin symptoms. Patients said skin improvement was greatest after cutting alcohol (53.8%), gluten (53.4%) and nightshades (52.1%). Meanwhile, adding fish oil/mega-3 improved symptoms for 44.6%, vegetables for 42.5%, and oral vitamin D for 41%. 

7. Diet matters to cardiovascular disease, no matter your nationality   

How can we really tell what foods affect our chances of suffering a heart attack when people all over the globe eat differently? A huge 2008 effort known as the INTERHEART study examined more than 16,000 people from 52 countries, breaking down dietary patterns into three categories: Oriental, with high intake of tofu, soy and other sauces; Western, with high intake of fried foods, salty snacks, eggs and meat; and “prudent,” with high intake of fruits and vegetables. Assigning dietary risk scores to each diet, researchers found that an unhealthy intake raised the risk of heart attack globally, accounting for about 30% of the overall risk.

8. One food group can significantly lower diabetes risk  

With more than 29 million Americans suffering from diabetes – roughly 9% of the population – this scourge is quickly reaching epidemic proportions. But Chinese researchers tracking 500,000 adults over 7 years reported in April 2017 that eating fresh fruit daily could reduce the risk of diabetes by 12%. The study also revealed that those who already had diabetes who ate fruit regularly were less likely to die or suffer diabetes complications such as eye problems than those who rarely or never ate fruit.

9. Going nuts over colon cancer  

Nuts such as walnuts, pecans and almonds are already well-known to lower heart disease risk, but researchers revealed that they can also cut the chance of colon cancer coming back. An observational study presented at the 2017 American Society of Clinical Oncology conference of 826 patients with stage 3 colon cancer showed that those consuming two or more ounces of nuts each week had a 42% lower chance of recurrence and 57% lower chance of death than patients who didn’t consume nuts.

10. Another reason to avoid drinking soda  

It’s bad for our teeth and our waistlines, but soda is also bad for our brain health, according to 2012 research in the American Journal of Clinical Nutrition. Tracking 84,000 women and more than 43,000 men for more than two decades, scientists determine that higher those who drank one or more sugar-sweetened or low-calorie sodas each day had a 16% higher risk of stroke. We can lower our risk by substituting other beverages for soda, researchers said.

Maureen Salamon is a widely published health and medical writer who has written for The New York Times, The Atlantic, CNN.com, HealthDay, The Dallas Morning News and other major publications.