The human mind prefers a healthy carotenoid glow over a suntan

In spite of the well-known damaging effects of the sun on our skin, many of us still perceive a tan as healthy-looking. But you don’t need to risk the health of your skin in the sun or a tanning bed to make it look healthy - the sun isn’t the only factor that can alter skin color.

Carotenoids are a group of 600 antioxidants including alpha-carotene, beta-carotene, lycopene, lutein, zeaxanthin, and astaxanthin. The richest sources of carotenoids are green, orange, and red vegetables and fruits. Many health-promoting phytochemicals, such as carotenoids, flavonoids, and phenols are pigment molecules that provide both attractive colors and health benefits. We are drawn to the vibrant colors of fresh produce that signal health benefits, and a new study has found that we can discern with our eyes how healthy the diet of a potential mate is.

 

Pigmentation in many species is perceived as a sign of health – birds for example. Carotenoids (both dietary and self-produced) are responsible for the bright feather colors of male birds, which make them more attractive to potential mates. There is evidence that in birds, dietary carotenoids do not merely serve this cosmetic purpose – increased carotenoid intake in birds may also improve color vision, sperm quality, and the health of offspring. [1]

The new study investigated people’s perception of skin ‘lightness’ and ‘yellowness’ – yellowness is influenced by both carotenoids and melanin (melanin increases in response to sun exposure). Researchers asked subjects to choose from sets of photos of two different skin colors – one whose yellowness was due to melanin, and one due to carotenoids – which skin color appeared healthier. Subjects consistently chose carotenoid coloration over melanin coloration. [2]

According to first author of the paper Ian Stephen, “We found that, given the choice between skin colour caused by suntan and skin colour caused by carotenoids, people preferred the carotenoid skin colour, so if you want a healthier and more attractive skin colour, you are better off eating a healthy diet with plenty of fruit and vegetables than lying in the sun.” [3]

There is a direct relationship between skin appearance and health – if your skin does not have an orange tinge, then you are not on a healthy diet. You can even quantify your skin carotenoid levels, which reflect dietary carotenoid intake, using a specialized scanner. [4, 5] I use one of these scanners in my medical practice to confirm that phytochemicals have accumulated in the skin of patients, affording them protection against cancer and other chronic diseases. Plus these phytonutrients in the skin offer protection from sun damage, aging of the skin and skin cancer from sun exposure. [6]

So eating carotenoid-rich food is not only a path to excellent health – it’s also a way to look good!

 

References:
1. Carotenoids Are Cornerstone of Bird's Vitality. ScienceDaily, 2009.
2. Stephen, I.D., Coetzee, V., Perrett, D.I., Carotenoid and melanin pigment coloration affect perceived human health. Evolution and Human Behavior, 2010.
3. Looking good on greens. Eurekalert!, 2011.
4. Ermakov, I.V. and W. Gellermann, Validation model for Raman based skin carotenoid detection. Arch Biochem Biophys, 2010. 504(1): p. 40-9.
5. Ermakov, I.V., et al., Resonance Raman detection of carotenoid antioxidants in living human tissue. J Biomed Opt, 2005. 10(6): p. 064028.
6. Nichols, J.A. and S.K. Katiyar, Skin photoprotection by natural polyphenols: anti-inflammatory, antioxidant and DNA repair mechanisms. Arch Dermatol Res, 2010. 302(2): p. 71-83.

 

Green and orange vegetable consumption - an indicator of longevity

No matter how many different dietary theories there are out there, pretty much everyone agrees that vegetables are “good for you”. But how good they truly are has been debated – there are plenty of observational studies linking vegetable consumption to favorable health outcomes, but other studies have made headlines by casting doubt on how powerful plant foods are for preventing disease. The data from these observational studies is often flawed simply because the majority of people in the Western world don’t eat enough vegetables to have a measurable impact on their risk of chronic disease – only about 25% of Americans eat the recommended three one-cup servings of vegetables each day.[1] Also, total vegetable consumption isn’t necessarily an accurate indicator of the healthfulness of one’s diet, since some vegetables are far more nutrient-dense than others. Of course, long-term controlled trials of consumption of a high-nutrient vegetable-based (nutritarian) diet have not yet been published (with the Nutritional Research Project, I aim to fill this gap in the medical literature). Some long-term observational studies, however, do provide clear, high-quality data demonstrating that vegetable consumption is an important factor in chronic disease prevention – a recent study on serum α-carotene levels and risk of death provides such data.

Alpha-carotene is one of over six-hundred different carotenoids, a family of antioxidants that also includes β-carotene, lycopene, lutein, zeaxanthin, and astaxanthin. Carotenoids help to defend the body’s tissues against oxidative damage, which is a natural byproduct of our oxygen-dependent metabolism. [2] Oxidative damage to DNA, proteins, and lipids is a known contributor to chronic disease and an accepted mechanism of aging. The body’s defenses against oxidative damage consist of naturally produced as well as diet-derived antioxidant molecules.

Many prospective studies in the past few years have supported the epidemiologic association between plasma carotenoids and reduced risk of disease and/or death. [3-6] However, these studies didn’t differentiate between carotenoids from food and those from supplements. Carotenoid supplements have failed to duplicate this effect in clinical trials. In fact, supplemental carotenoids are likely to be harmful. A recent meta-analysis of several trials found a 7% increase in mortality risk in subjects taking β-carotene supplements. [7, 8] Also, high serum β-carotene has been associated with decreased lung cancer risk, but β-carotene supplements may increase the risk of lung cancer, especially in smokers.[9] Attempting to duplicate the beneficial effects of carotenoid-rich foods with isolated nutrients is foolish - it completely neglects the contribution of additional and/or synergistic effects of other nutrients contained in those foods.

Beta-carotene is the most widely studied carotenoid, but α-carotene more accurately reflects vegetable intake because α-carotene is not present in most multivitamins and supplements. It is also an excellent marker of high-nutrient vegetable intake, since dark green and orange colored vegetables are the richest sources of alpha carotene. Green vegetables are the highest in overall nutrient density, and of course they are the foods richest in alpha carotene.

This study measured baseline serum α-carotene and tracked deaths in the 15,318 participants over a fourteen-year follow-up period. After controlling for potential confounding factors, the researchers found a significant trend – increasing serum α-carotene associated with decreased risk of death from all causes. Those with the highest serum α-carotene had a 39% decrease in risk of death compared to those with the lowest serum α-carotene. Similar relationships were found between serum α-carotene and risk of death from cardiovascular disease, all causes other than CVD, and cancer.

Serum α-carotene % Decrease in risk of death from all causes
0-1 µg/dl (Reference group)
2-3 µg/dl 23%
4-5 µg/dl (average 4.79 µg/dl) 27%
6-8 µg/dl 34%
≥9 µg/dl  39%

Alpha-carotene itself does provide significant antioxidant benefit –but more importantly α-carotene is a marker of the thousands of additional compounds, working synergistically to keep the body healthy present in green and orange vegetables. [10]

These results suggest that not only quantity of vegetable consumption, but the type of vegetables consumed has a major impact on health. This is the main principle behind the nutritarian diet – eating according to nutrient density. This large, long term study gives much support to the concept of nutritarianism, as many foods high in α-carotene tend to be high in micronutrients overall – the foods that make up the base of the nutritarian food pyramid. And of course keep in mind, even in the highest alpha carotene group in this study, the levels of vegetable consumption as a percent of total calories are likely not nearly as high as in someone following a nutritarian diet. Also, the serum level of alpha carotene in someone following a typical Western diet likely reflects mostly carrot consumption compared to the wide variety of green and yellow vegetables that would be consumed as part of a nutritarian diet, from which further benefits would be expected to accrue from the variety of phytochemicals contained within those vegetables.

Examples of foods with a high α-carotene to calorie ratio[11]:

  • Bok choy
  • Cabbage
  • Red peppers
  • Carrots
  • Swiss chard
  • Green peppers
  • Asparagus
  • Collards
  • Broccoli
  • Winter squash
  • Peas

 

 

 

 

 

Now imagine if such a study was done on people eating the dietary quality I recommend, which would result in levels even much higher than those in the study, and imagine if a diet of this quality was done for more than 10 years and with other synergistic foods, such as mushrooms, onions, berries and seeds. Just imagine...

 

References:

1. State-Specific Trends in Fruit and Vegetable Consumption Among Adults --- United States, 2000--2009. U.S. Centers for Disease Control and Prevention. Morbidity and Mortality Weekly Report September 10, 2010 November 24, 2010]; Available from: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5935a1.htm.
2. Krinsky, N.I. and E.J. Johnson, Carotenoid actions and their relation to health and disease. Mol Aspects Med, 2005. 26(6): p. 459-516.
3. Lauretani, F., et al., Low total plasma carotenoids are independent predictors of mortality among older persons: the InCHIANTI study. Eur J Nutr, 2008. 47(6): p. 335-40.
4. Akbaraly, T.N., A. Favier, and C. Berr, Total plasma carotenoids and mortality in the elderly: results of the Epidemiology of Vascular Ageing (EVA) study. Br J Nutr, 2009. 101(1): p. 86-92.
5. Ito, Y., et al., A population-based follow-up study on mortality from cancer or cardiovascular disease and serum carotenoids, retinol and tocopherols in Japanese inhabitants. Asian Pac J Cancer Prev, 2006. 7(4): p. 533-46.
6. Ray, A.L., et al., Low serum selenium and total carotenoids predict mortality among older women living in the community: the women's health and aging studies. J Nutr, 2006. 136(1): p. 172-6.
7. Bjelakovic, G., et al., Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Cochrane Database Syst Rev, 2008(2): p. CD007176.
8. Bjelakovic, G., et al., Systematic review: primary and secondary prevention of gastrointestinal cancers with antioxidant supplements. Aliment Pharmacol Ther, 2008. 28(6): p. 689-703.
9. Druesne-Pecollo, N., et al., Beta-carotene supplementation and cancer risk: a systematic review and metaanalysis of randomized controlled trials. Int J Cancer, 2010. 127(1): p. 172-84.
10. Li, C., et al., Serum {alpha}-Carotene Concentrations and Risk of Death Among US Adults: The Third National Health and Nutrition Examination Survey Follow-up Study. Arch Intern Med, 2010.
11. NutritionData.com: Nutrient Search Tool. 2009]; Available from: http://www.nutritiondata.com/tools/nutrient-search.

 

Eat leafy greens to see clearly

 

Carotenoids are pigments present in fruits and vegetables. An interesting fact about carotenoids is that carotenoids exert their beneficial effects by traveling to and then concentrating in specific tissues in the body. For example, lycopene, a carotenoid found in tomatoes, travels to the prostate, where it has potent anti-cancer effects

Lutein and zeaxanthin, which are found in leafy greens like kale, travel to the central area of the retina (called the macula), and are the only known carotenoids located in the human visual system. Previous research has shown that these pigments are protective against age-related macular degeneration. Scientists now have evidence that these macular pigments also play important roles in visual performance.

Since our bodies can’t produce these pigments, levels of lutein and zeaxanthin in the retina depend on the amounts consumed in the diet. 

Light must pass through lutein and zeaxanthin before being transmitted to photoreceptor cells that will produce a message from the light to send to the brain. As light passes through, some short wavelength (blue) light is absorbed by the macular pigments. For this reason, there was a theory that macular pigments have a light-filtering function in vision.

An analysis of several studies on the subject of macular pigments and visual performance confirms this theory. The authors evaluated the evidence and concluded that lutein and zeaxanthin likely improve the following visual functions by acting as light filters:

  • Discomfort glare – For example, experiencing bright light after being in a dark room. The wavelengths that macular pigments are capable of absorbing produce the least discomfort, suggesting that macular pigments protect the eye from this overstimulation by filtering the light.
  • Disability glare – Subjects with higher levels of macular pigment show improved visibility of objects in the presence of glare.
  • Photostress recovery – Elevated macular pigment values decrease the time necessary to recover vision following exposure to bright light.
  • Contrast – Macular pigments increase visibility and edge definition of objects in the atmosphere, possibly by absorbing blue sky light.

Rich sources of lutein and zeaxanthin include kale, spinach, turnip greens, swiss chard, and collards.


Reference:

Stringham JM et al. The Influence of Dietary Lutein and Zeaxanthin on Visual Performance. Journal of Food Science 2009

 

Beta Carotene Supplements May Increase Lung Cancer Risk

Published in the American Journal of Epidemiology, a new 10-year analysis of more than 77,000 adults, men and women ages 50 to 76, revealed long term use of high-dose beta carotene supplements may heighten the risk of lung cancer, especially in smokers. Scientists used questionnaires to assess participants’ intake of dietary supplements and then tracked them for the next four years. These findings mirror a 2007 study showing vitamin C and E and folate supplements do not decrease the risk of lung cancer; ScienceDaily explains.

According to Dr. Fuhrman high-dose beta carotene supplements interfere with the absorption of antioxidants, like carotenoids and other antioxidants found in fruits and vegetables. This can increase cancer-risk. That’s why Dr. Fuhrman’s formulates his vitamins without beta carotene.

But getting beta carotene from veggies is just fine! Foods like carrots, mangos and oranges, as well as leafy greens like cabbage, Bok Choy and broccoli are loaded with beta carotene and other health-protecting antioxidants and phytochemicals.

Vitamins aren’t magic pills! Previous reports show vitamins alone can’t prevent heart disease or prostate cancer, i.e. a bacon cheese burger with a side of Centrum Silver isn’t healthy.

Image credit: Teresa Stanton