The conventional wisdom is that investors without advisors often make the wrong choices. They don’t save enough. They botch their retirement planning. People with advisors do better.

But that’s not always true.

Some advisors, specifically plan advisors, are not helping but hurting investors when it comes to achieving goals, as many people fall behind in their retirement savings.

A new study finds that the defined contribution recommendations of some retirement plan advisors are actually generating inferior returns that lag benchmarks.

“It is critical for plan sponsors that such recommendations are beneficial to participants,” according to the study, “Use of Advisors and Retirement Plan Performance.”

Rui Yao, a University of Missouri financial planning expert and study co-author, examined retirement plan performance in 401(k)s based on plan advisor recommendations.

The study found investment advisor performance in defined benefit plans over a recent three-year period was “significantly and negatively” related to retirement plan performance in 2013, 2014 and 2015.

“For example, in 2013, the estimated average treatment effect of advisors was -0.04% in monthly expected returns, and this difference would be -0.48% annually. Over the long run, as in most retirement planning cases, this compounding effect would have a large economic impact,” according to the study.

Getting the most from private savings and persuading Americans to save for retirement are essential, as a recent National Institute on Retirement Security study found millions of Americans have inadequate savings.

The Yao study looked at retirement plan performance based on the use of a plan advisor and the plan size and plan choices offered. It found that plan advisors alone are not enough to ensure strong retirement plan performance.

Why are some plan advisors hurting retirement saving efforts?

Yao, a CFP, contended that some advisors “are incentivized to market different funds, and while they are financial experts, they do not always have a fiduciary responsibility to their clients.”

Henry Luong Hoang, a CFP in Newport Beach, Calif., says effective plans must be properly structured.

“The first crucial step is to set up the plan correctly initially to avoid conflicts of interest between the advisor and client,” Hoang says. “By taking full fiduciary responsibility and removing incentives for choosing select funds, an advisor can keep her sole focus on quality advice and successful outcomes for clients.”

Clients should understand these advisor relationships, Yao says. “They are required by law to disclose this information, so it’s absolutely OK—and advisable—for plan participants to ask their employer what kind of legal responsibility the plan advisor bears.”

Indeed, another advisor wondered if plan advisors are working for the employer/plan sponsor or for the plan participant and where is there legal accountability?

“Most broker-dealer advisors don’t have the fiduciary responsibility when it comes to retirement plan investments,” says Michael C. Whitman, a CFP in Chapel Hill, N.C.

“A lot of times, the retirement plans themselves will have a fiduciary that picks the investment lineup, but the advisor is really there to create an asset allocation pursuant to the client's goals,” he adds. “Advisors are also there to help with basic financial questions, apart from them getting hired on a more individual basis.”

Whitman says some firms actively manage funds inside of a retirement plan.

“But those are expensive, and clients rarely want to pay for that (in my opinion). The incentivization only comes to play when a mutual fund 401(k) plan is chosen and the advisor is paid a sales charge for the funds purchased in the plan, and not a fee to advise,” Whitman says.

Part of the problem with poor advisor recommendations, says another CFP, is that the plan advisor is only allowed to make recommendations on the assets of a specific plan.

“These advisors are strictly limited to not only what they can offer in terms of advice but how they can recommend that advice be implemented,” says Karl Leonard Hicks, an advisor in Riverside, Calif. “This is different from an advisor like an RIA, who can take a broader view of the client and their situation.”

Yao says it is important that plan participants ask questions. How is the plan paying fees? And to whom?

Be diligent in reviewing the overall expenses in managing a retirement plan, Hoang adds.

“Oftentimes, smaller plans have much higher fees, putting participants at a disadvantage before even selecting their investments,” he says.

Hoang contends that if “you have a plan that does not provide any benefits beyond maximizing your employer match, consider contributing up to your employer's full match and opening up your own IRA or Roth IRA.”

Indeed, Yao says plan participants should no more “over rely” on 401(k)s than they should over rely on Social Security, which has had cutbacks over the years and may face more.

She argues the average plan participant should also develop other sources of retirement income to achieve retirement goals.

And tracking them, having someone to ensure the plan advisor is doing an effective job, may be the ultimate argument for the advisory industry.