Quora .

What are examples of outdated medical advice?

This question originally appeared on Quora. Answer by Dr. David Chan, physician from Stanford Oncology.

1. The long standing advice to avoid saturated fats and eat more carbs is wrong.

Remember the food pyramid from the 1970s? They instructed Americans to ingest 6 to 11 servings of carbs daily. That ushered in the obesity epidemic because that kind of diet stimulates hunger by peaking blood sugar and then insulin levels to chase it, leading to weight gain and type 2 diabetes. Instead, we now know that ingesting saturated fat as part of our diet, lowers hunger and reduces obesity.

We worried about ingesting cholesterol but our cholesterol level is primarily genetically controlled and based on what is made from our livers from ingested calories, not so much due to the amount of cholesterol we ingest.

Rebuilding the Food Pyramid

2. The idea that every parent had that skim milk is better for kids than whole milk has recently been debunked.

It turns out that kids who drink whole milk have lower obesity levels maybe because they are less hungry and eat less.

Whole Milk Or Skim? Study Links Fattier Milk To Slimmer Kids

3. The recommendations that taking multivitamin supplements is good for us is wrong.

The large bulk of studies show that taking a multivitamin does not improve health with the exception for those with a specific illness such as macular degeneration or documented deficiency. The vitamin industry is big business, nearly completely unregulated, and we’re putting billions of dollars of worthless vitamins in our toilets in America. Taking a multi-vitamin is no substitute to eating a diet rich in fruits and vegetables, avoiding obesity, minimizing alcohol and not smoking. Most vitamins studies show a higher cancer rate, not lower.

Don’t Take Your Vitamins

4. Salt in our diets/food is not bad for most of us.

The idea to eat a low salt diet is one of the most poorly documented recommendations that the U.S. Department of Agriculture promoted. It was based on the personal bias and faulty research of a cardiologist assigned to make a recommendation for the American Heart Association.

This week a meta-analysis of seven studies involving a total of 6,250 subjects in the American Journal of Hypertension found no strong evidence that cutting salt intake reduces the risk for heart attacks, strokes or death in people with normal or high blood pressure. In May European researchers publishing in the Journal of the American Medical Association reported that the less sodium that study subjects excreted in their urine — an excellent measure of prior consumption — the greater their risk was of dying from heart disease. These findings call into question the common wisdom that excess salt is bad for you, but the evidence linking salt to heart disease has always been tenuous.

It's Time to End the War on Salt

5. It’s also not true that fresh fruits and vegetables are healthier for us than frozen.

It turns out that prolonged shipping and shelf life at the supermarkets causes degredation of the healthy nutrients. For all of us on a budget, that’s great news. Frozen may be healthier. Who knew?

Frozen food IS better than fresh: Higher levels of vitamins and antioxidants in frozen fruit and vegetables say scientists

More from Quora: