The definitive, scientific answers to 20 health questions everyone has

In the past few years alone, we got more evidence that coffee isn't a cause of cancer and the debate over the health effects of sugar became even more heated.

To help you parse out what works from what's merely myth, we compiled the definitive (at least for now) answers to some of the most pressing health questions, based on the book "Your Health: What Works, What Doesn't."

Here's what the science has to say.

Does sugar make you hyper?

Short answer: No

The National Institutes of Health has made it pretty clear that additives and dyes added to food have effects that are "s

Does cough syrup work?

Short answer: No

It's been a while since doctors came to agree that most over-the-counter cough medicines don't work. In 2014, Australian researchers published similar conclusions that the syrups typically contain doses of codeine and antihistamines that are too small to be effective and can be harmful for children. And in April 2017, the Food and Drug Administration restricted the use of cough syrup that has codeine in it, saying children under 12 should not use the medication.

Prescription cough suppressants such as levodropropizine, however, might have a better shot.

Does olive oil prevent heart disease?

Short answer: Yes

study

Do sugary soft drinks lead to diabetes?

Short answer: Yes

Sugary drinks are associated with type 2 diabetes, according to a 2010 analysis of studies on the relationship. Compared with those who had less than one sugary beverage a month, those who had about one to two servings a day had a 26% greater risk of developing Type 2 diabetes, the analysis found.

And it's not just diabetes —excessive sugar consumption can lead to a host of problems. For example, sugar-sweetened beverages are also associated with weight gain and diabetes, a 2006 review that looked at 50 years worth of studies found.

In fact, one professor of medicine wrote that he'd choose a diet soft drink over one with sugar, based on sugar's link to weight gain and obesity.

Do I need sunscreen with more than 30 SPF?

Short answer: No

93% of UVB rays

The Food and Drug Administration, which is in charge of regulating sunscreen, says the more important factor is going for a sunscreen labeled "broad spectrum." That means the sunscreen's protection against ultraviolet A rays, or UVA, is proportional to protection against ultraviolet B rays. Yes, you can go up to 50 SPF and be safer, but as long as you stay above SPF 15 with the broad spectrum, you should be set. Just be sure to reapply frequently (the FDA suggests every two hours or so).

Another way to think about what SPF to use:

Is the MSG in Chinese food likely to give you a headache?

Short answer:

Do nuts make you fat?

Short answer: No

Unless you're eating pounds of almonds every day, nuts most likely won't make you fat. 3.4 grams of saturated fat FDA's standard of less than 2 grams allowed to be considered healthy

Is walking as effective as running?

Short answer: Yes

But really, it depends on what effect you're looking for. If you're going for heart health, yes, there's no difference. If you're going for weight loss, vigorous exercise might be better. As for your knees, going for a run might actually do more to help than previously thought, according to a 2011 meta-analysis of running and knee joint studies.

Is drinking fruit juice as good for you as eating fruit?

Short answer: No

You don't want to lose the fiber that's in the peels and pulp of the fruit — and let's face it, most of us don't get enough fiber as it is. A 2014 study comparing orange juice to oranges, however, suggested that the juice form might be able to unlock nutrients like flavonoids and carotenoids compared with whole oranges, though that doesn't overrule the lack of fiber.

So if you're looking for the best of both worlds, opt in for pulp so you at least get a little bit.

Are all wheat breads better for you than white bread?

Short answer: No

Not all wheat breads are created equal, so take note. Though most white bread is made with refined grains that skip out a lot of the fiber and nutrients, there are whole-wheat white breads that are just as healthy as whole-wheat breads.

Regardless of your color preference, make sure you're getting whole wheat: bran, germ, endosperm, the whole package.

Can a hot tub make me sick?

Short answer: Yes

Hot tubs are a really great breeding grounds for germs. According to data on more than 84,000 inspections released in 2016 by the Centers for Disease Control and Prevention, one in eight public swimming places (pools as well as hot tubs) had to be shut down because of health and safety violations. The most common reasons had to do with improper pH levels or disinfectant concentrations.

Many outbreaks in public pools and hot tubs are caused by Cryptosporidium, a parasite that can cause gastrointestinal illness and is pretty resistant to chlorine. But that doesn't mean you should steer clear of the jets of hot water or the local pool during the summer; just try not to swallow a bunch of water and know some of the warning signs.

Does coffee cause cancer?

Short answer: No

In June 2016, the World Health Organization's International Agency for Research on Cancer (IARC) "found no conclusive evidence for a carcinogenic effect of drinking coffee." However, the agency did find that hot beverages "probably causes" cancer of the esophagus — a type of cancer that's not very common.

For a long time the WHO categorized coffee as "s argued in Slate in 2015, coffee is consumed by such a large population and has been so well studied that it's really unlikely that it's a carcinogen. And, as the IARC found, drinking coffee might reduce the risk for cancers such as liver and uterine endometrium.

Do eggs raise cholesterol levels?

Short answer:

Can you drink too much water?

Short answer:

Can yogurt ease digestive problems?

Short answer:

Do whitening toothpastes whiten teeth more than regular toothpastes?

Short answer:

Is it safe to microwave food in plastic containers?

Short answer:

Can watching TV ruin your eyesight?

Short answer:

Is red wine better for you than white wine?

Short answer:

Is bottled water better for you than tap water?

Short answer: No

Unless you live in an area with known unclean drinking water, opting for bottled water isn't doing you much good. In fact, you could be missing out on fluoride, which is important for keeping teeth from decaying. And it's not doing the environment any good at all.

The definitive, scientific answers to 20 health questions everyone has

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