With the holiday season and the associated over-eating and food indiscretions behind us, many of us are reaching out to salads as part of our New Year’s resolutions. That’s good, but … arm yourself with essential science if you truly wish to undo the sins of the recent past and get the most from your salads.
Salad dressings – too often liberally poured and underestimated for their nutritional importance – are riddled with myths and misinformation. The simple rule ‘the less fat, the better’ holds true for dairy products, meats and poultry, but does not necessarily apply to salads and salad dressings. In fact, the single, biggest factor to a healthy salad is the dressing – and full-fat dressing at that.
For those trying to lose weight, switching from an oil-based dressing to a low-fat or fat-free dressing may seem to make sense. But sparing 100 calories or so (per 2 tablespoons) comes at a big cost.
Why fat in salad dressing is good for you
Although lettuce consists primarily of water, it is also a powerhouse of phytochemicals with antioxidant benefits. In addition to nutrients such as vitamin C, potassium, fiber and vitamin A, dark-green-leaf lettuce also contains beta carotene, which may reduce the risk of developing some forms of cancer. Romaine lettuce and kale are highly nutritious, and also an excellent source of vitamin A, beta carotene, lycopene, lutein, and other nutrients.
But, if you are dousing them with fat-free salad dressings, you might as well flush your money down the toilet – literally – because scientific studies have shown that fat is necessary to help your body absorb valuable nutrients such as beta-carotene, lycopene, and lutein.
A University of Iowa study demonstrated this phenomenon by measuring the carotenoids appearing in blood plasma in volunteer diners who were fed fresh-vegetable salads with different salad dressings: fat free, reduced fat, or conventional full fat. Each salad included romaine lettuce, spinach leaves, grated carrots, and cherry tomatoes.
Volunteers who dined on salads with fat-free dressing absorbed little or no carotenoids, including beta-carotene and lycopene into their plasma. Those who added reduced-fat dressing improved matters only slightly, while diners who were provided full-fat dressing absorbed the maximum amount of carotenoids.
The conclusion was obvious: that absorption of fat-soluble nutrients and bioactives requires the presence of fat, which improves their bio-availabilty. The addition of vegetable oil to raw-vegetable salads increases the absorption of carotenoids and fat-soluble vitamins, and that nutrient absorption is minimal in the absence of fat. The carotenoid absorption is significantly greater when salad vegetables are topped with full-fat and reduced-fat dressings compared to fat-free dressings.
In another study participants eating avocado with salad absorbed five times more lutein, 15 times more beta-carotene and seven times more alpha-carotene than those who only ate salad. Similarly, there are studies showing that the addition of nuts can enhance the absorption of phytonutrients from raw vegetables.
Additionally, healthful monounsaturated fats in salad dressings made with olive, grapeseed, almond or canola oils may help prevent heart disease and other cardiovascular illnesses. What's more, you may be missing out on important disease protection by going oil free. Many salad dressings provide an essential fatty acid, alpha-linolenic acid, which helps protect women against fatal heart attacks, as well as the ever-important vitamin E, which offers a wealth of benefits to any salad eater.
Keys to a healthy salad
There are three keys to keeping a salad healthy:
1) the type and quality of vegetables, including the lettuce;
2) additions to the salad such as cheese, meat, fish, vegetables or fruit; and, most importantly,
3) the type and amount of the dressing used on the salad.
Be cautious when opting for prepared salads, especially at fast-food outlets. For instance, a single-serving size of a taco salad from Taco Bell contains 906 calories and 49 grams of fat. Wendy’s Chicken BLT Salad with Homestyle Chicken Fillet Salad contains 790 calories and 53 grams of fat.
So go ahead. The next time you're loading your salad with Romaine, iceberg, kale, bell peppers, spinach, tomatoes and broccoli, add something “naughty” like nuts, cheese, avocados, toasted or crushed flaxseed, chia seed and oils – but not too much! Just a little bit will go a long way.
Melody J Brown, Mario G Ferruzzi, Minhthy L Nguyen, Dale A Cooper, Alison L Eldridge, Steven J Schwartz and Wendy S White. Carotenoid bioavailability is higher from salads ingested with full-fat than with fat-reduced salad dressings as measured with electrochemical detection. American Journal of Clinical Nutrition, Vol. 80, No. 2, 396-403, August 2004
Su LJ, Arab L. Salad and raw vegetable consumption and nutritional status in the adult US population: results from the Third National Health and Nutrition Examination Survey. Journal of the American Dietetic Association, Vol. 106, No. 9, 1394-404, September, 2006.